xref: /petsc/src/ksp/pc/impls/bddc/bddc.c (revision 36e030eb8e58b038c8a980256364da8f785d22b6)

/* TODOLIST
   DofSplitting and DM attached to pc.
   Exact solvers: Solve local saddle point directly for very hard problems
     - change prec_type to switch_inexact_prec_type
     - add bool solve_exact_saddle_point slot to pdbddc data
   Inexact solvers: global preconditioner application is ready, ask to developers (Jed?) on how to best implement Dohrmann's approach (PCSHELL?)
   change how to deal with the coarse problem (PCBDDCSetCoarseEnvironment):
     - mind the problem with coarsening_factor
     - simplify coarse problem structure -> PCBDDC or PCREDUDANT, nothing else -> same comm for all levels?
     - remove coarse enums and allow use of PCBDDCGetCoarseKSP
     - remove metis dependency -> use MatPartitioning for multilevel -> Assemble serial adjacency in ManageLocalBoundaries?
     - Add levels' slot to bddc data structure and associated Set/Get functions
   code refactoring:
     - pick up better names for static functions
   check log_summary for leaking (actually: 1 Vector per level )
   change options structure:
     - insert BDDC into MG framework?
   provide other ops? Ask to developers
   remove all unused printf
   remove // commments and adhere to PETSc code requirements
   man pages
*/

/* ----------------------------------------------------------------------------------------------------------------------------------------------
   Implementation of BDDC preconditioner based on:
   C. Dohrmann "An approximate BDDC preconditioner", Numerical Linear Algebra with Applications Volume 14, Issue 2, pages 149-168, March 2007
   ---------------------------------------------------------------------------------------------------------------------------------------------- */

#include "bddc.h" /*I "petscpc.h" I*/  /* includes for fortran wrappers */
#include <petscblaslapack.h>

/* -------------------------------------------------------------------------- */
#undef __FUNCT__
#define __FUNCT__ "PCSetFromOptions_BDDC"
PetscErrorCode PCSetFromOptions_BDDC(PC pc)
{
  PC_BDDC         *pcbddc = (PC_BDDC*)pc->data;
  PetscErrorCode ierr;

  PetscFunctionBegin;
  ierr = PetscOptionsHead("BDDC options");CHKERRQ(ierr);
  /* Verbose debugging of main data structures */
  ierr = PetscOptionsBool("-pc_bddc_check_all"       ,"Verbose (debugging) output for PCBDDC"                       ,"none",pcbddc->dbg_flag      ,&pcbddc->dbg_flag      ,PETSC_NULL);CHKERRQ(ierr);
  /* Some customization for default primal space */
  ierr = PetscOptionsBool("-pc_bddc_vertices_only"   ,"Use vertices only in coarse space (i.e. discard constraints)","none",pcbddc->vertices_flag   ,&pcbddc->vertices_flag   ,PETSC_NULL);CHKERRQ(ierr);
  ierr = PetscOptionsBool("-pc_bddc_constraints_only","Use constraints only in coarse space (i.e. discard vertices)","none",pcbddc->constraints_flag,&pcbddc->constraints_flag,PETSC_NULL);CHKERRQ(ierr);
  ierr = PetscOptionsBool("-pc_bddc_faces_only"      ,"Use faces only in coarse space (i.e. discard edges)"         ,"none",pcbddc->faces_flag      ,&pcbddc->faces_flag      ,PETSC_NULL);CHKERRQ(ierr);
  ierr = PetscOptionsBool("-pc_bddc_edges_only"      ,"Use edges only in coarse space (i.e. discard faces)"         ,"none",pcbddc->edges_flag      ,&pcbddc->edges_flag      ,PETSC_NULL);CHKERRQ(ierr);
  /* Coarse solver context */
  static const char *avail_coarse_problems[] = {"sequential","replicated","parallel","multilevel",""}; //order of choiches depends on ENUM defined in bddc.h
  ierr = PetscOptionsEnum("-pc_bddc_coarse_problem_type","Set coarse problem type","none",avail_coarse_problems,(PetscEnum)pcbddc->coarse_problem_type,(PetscEnum*)&pcbddc->coarse_problem_type,PETSC_NULL);CHKERRQ(ierr);
  /* Two different application of BDDC to the whole set of dofs, internal and interface */
  ierr = PetscOptionsBool("-pc_bddc_switch_preconditioning_type","Switch between M_2 (default) and M_3 preconditioners (as defined by Dohrmann)","none",pcbddc->prec_type,&pcbddc->prec_type,PETSC_NULL);CHKERRQ(ierr);
  ierr = PetscOptionsInt("-pc_bddc_coarsening_ratio","Set coarsening ratio used in multilevel coarsening","none",pcbddc->coarsening_ratio,&pcbddc->coarsening_ratio,PETSC_NULL);CHKERRQ(ierr);
  ierr = PetscOptionsTail();CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

/* -------------------------------------------------------------------------- */
EXTERN_C_BEGIN
#undef __FUNCT__
#define __FUNCT__ "PCBDDCSetCoarseProblemType_BDDC"
static PetscErrorCode PCBDDCSetCoarseProblemType_BDDC(PC pc, CoarseProblemType CPT)
{
  PC_BDDC  *pcbddc = (PC_BDDC*)pc->data;

  PetscFunctionBegin;
  pcbddc->coarse_problem_type = CPT;
  PetscFunctionReturn(0);
}
EXTERN_C_END

/* -------------------------------------------------------------------------- */
#undef __FUNCT__
#define __FUNCT__ "PCBDDCSetCoarseProblemType"
/*@
 PCBDDCSetCoarseProblemType - Set coarse problem type in PCBDDC.

   Not collective

   Input Parameters:
+  pc - the preconditioning context
-  CoarseProblemType - pick a better name and explain what this is

   Level: intermediate

   Notes:
   Not collective but all procs must call this.

.seealso: PCBDDC
@*/
PetscErrorCode PCBDDCSetCoarseProblemType(PC pc, CoarseProblemType CPT)
{
  PetscErrorCode ierr;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(pc,PC_CLASSID,1);
  ierr = PetscTryMethod(pc,"PCBDDCSetCoarseProblemType_C",(PC,CoarseProblemType),(pc,CPT));CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

/* -------------------------------------------------------------------------- */
EXTERN_C_BEGIN
#undef __FUNCT__
#define __FUNCT__ "PCBDDCSetDirichletBoundaries_BDDC"
static PetscErrorCode PCBDDCSetDirichletBoundaries_BDDC(PC pc,IS DirichletBoundaries)
{
  PC_BDDC  *pcbddc = (PC_BDDC*)pc->data;
  PetscErrorCode ierr;

  PetscFunctionBegin;
  ierr = ISDestroy(&pcbddc->DirichletBoundaries);CHKERRQ(ierr);
  ierr = PetscObjectReference((PetscObject)DirichletBoundaries);CHKERRQ(ierr);
  pcbddc->DirichletBoundaries=DirichletBoundaries;
  PetscFunctionReturn(0);
}
EXTERN_C_END

/* -------------------------------------------------------------------------- */
#undef __FUNCT__
#define __FUNCT__ "PCBDDCSetDirichletBoundaries"
/*@
 PCBDDCSetDirichletBoundaries - Set index set defining subdomain part of
                              Dirichlet boundaries for the global problem.

   Not collective

   Input Parameters:
+  pc - the preconditioning context
-  DirichletBoundaries - sequential index set defining the subdomain part of Dirichlet boundaries (can be PETSC_NULL)

   Level: intermediate

   Notes:

.seealso: PCBDDC
@*/
PetscErrorCode PCBDDCSetDirichletBoundaries(PC pc,IS DirichletBoundaries)
{
  PetscErrorCode ierr;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(pc,PC_CLASSID,1);
  ierr = PetscTryMethod(pc,"PCBDDCSetDirichletBoundaries_C",(PC,IS),(pc,DirichletBoundaries));CHKERRQ(ierr);
  PetscFunctionReturn(0);
}
/* -------------------------------------------------------------------------- */
EXTERN_C_BEGIN
#undef __FUNCT__
#define __FUNCT__ "PCBDDCSetNeumannBoundaries_BDDC"
static PetscErrorCode PCBDDCSetNeumannBoundaries_BDDC(PC pc,IS NeumannBoundaries)
{
  PC_BDDC  *pcbddc = (PC_BDDC*)pc->data;
  PetscErrorCode ierr;

  PetscFunctionBegin;
  ierr = ISDestroy(&pcbddc->NeumannBoundaries);CHKERRQ(ierr);
  ierr = PetscObjectReference((PetscObject)NeumannBoundaries);CHKERRQ(ierr);
  pcbddc->NeumannBoundaries=NeumannBoundaries;
  PetscFunctionReturn(0);
}
EXTERN_C_END

/* -------------------------------------------------------------------------- */
#undef __FUNCT__
#define __FUNCT__ "PCBDDCSetNeumannBoundaries"
/*@
 PCBDDCSetNeumannBoundaries - Set index set defining subdomain part of
                              Neumann boundaries for the global problem.

   Not collective

   Input Parameters:
+  pc - the preconditioning context
-  NeumannBoundaries - sequential index set defining the subdomain part of Neumann boundaries (can be PETSC_NULL)

   Level: intermediate

   Notes:

.seealso: PCBDDC
@*/
PetscErrorCode PCBDDCSetNeumannBoundaries(PC pc,IS NeumannBoundaries)
{
  PetscErrorCode ierr;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(pc,PC_CLASSID,1);
  ierr = PetscTryMethod(pc,"PCBDDCSetNeumannBoundaries_C",(PC,IS),(pc,NeumannBoundaries));CHKERRQ(ierr);
  PetscFunctionReturn(0);
}
/* -------------------------------------------------------------------------- */
EXTERN_C_BEGIN
#undef __FUNCT__
#define __FUNCT__ "PCBDDCGetNeumannBoundaries_BDDC"
static PetscErrorCode PCBDDCGetNeumannBoundaries_BDDC(PC pc,IS *NeumannBoundaries)
{
  PC_BDDC  *pcbddc = (PC_BDDC*)pc->data;

  PetscFunctionBegin;
  *NeumannBoundaries = pcbddc->NeumannBoundaries;
  PetscFunctionReturn(0);
}
EXTERN_C_END

/* -------------------------------------------------------------------------- */
#undef __FUNCT__
#define __FUNCT__ "PCBDDCGetNeumannBoundaries"
/*@
 PCBDDCGetNeumannBoundaries - Get index set defining subdomain part of
                              Neumann boundaries for the global problem.

   Not collective

   Input Parameters:
+  pc - the preconditioning context

   Output Parameters:
+  NeumannBoundaries - index set defining the subdomain part of Neumann boundaries

   Level: intermediate

   Notes:

.seealso: PCBDDC
@*/
PetscErrorCode PCBDDCGetNeumannBoundaries(PC pc,IS *NeumannBoundaries)
{
  PetscErrorCode ierr;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(pc,PC_CLASSID,1);
  ierr = PetscUseMethod(pc,"PCBDDCGetNeumannBoundaries_C",(PC,IS*),(pc,NeumannBoundaries));CHKERRQ(ierr);
  PetscFunctionReturn(0);
}
/* -------------------------------------------------------------------------- */
EXTERN_C_BEGIN
#undef __FUNCT__
#define __FUNCT__ "PCBDDCGetDirichletBoundaries_BDDC"
static PetscErrorCode PCBDDCGetDirichletBoundaries_BDDC(PC pc,IS *DirichletBoundaries)
{
  PC_BDDC  *pcbddc = (PC_BDDC*)pc->data;

  PetscFunctionBegin;
  *DirichletBoundaries = pcbddc->DirichletBoundaries;
  PetscFunctionReturn(0);
}
EXTERN_C_END

/* -------------------------------------------------------------------------- */
#undef __FUNCT__
#define __FUNCT__ "PCBDDCGetDirichletBoundaries"
/*@
 PCBDDCGetDirichletBoundaries - Get index set defining subdomain part of
                              Dirichlet boundaries for the global problem.

   Not collective

   Input Parameters:
+  pc - the preconditioning context

   Output Parameters:
+  DirichletBoundaries - index set defining the subdomain part of Dirichlet boundaries

   Level: intermediate

   Notes:

.seealso: PCBDDC
@*/
PetscErrorCode PCBDDCGetDirichletBoundaries(PC pc,IS *DirichletBoundaries)
{
  PetscErrorCode ierr;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(pc,PC_CLASSID,1);
  ierr = PetscUseMethod(pc,"PCBDDCGetDirichletBoundaries_C",(PC,IS*),(pc,DirichletBoundaries));CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

/* -------------------------------------------------------------------------- */
EXTERN_C_BEGIN
#undef __FUNCT__
#define __FUNCT__ "PCBDDCSetDofsSplitting_BDDC"
static PetscErrorCode PCBDDCSetDofsSplitting_BDDC(PC pc,PetscInt n_is, IS ISForDofs[])
{
  PC_BDDC  *pcbddc = (PC_BDDC*)pc->data;
  PetscInt i;
  PetscErrorCode ierr;

  PetscFunctionBegin;
  /* Destroy ISs if they were already set */
  for(i=0;i<pcbddc->n_ISForDofs;i++) {
    ierr = ISDestroy(&pcbddc->ISForDofs[i]);CHKERRQ(ierr);
  }
  ierr = PetscFree(pcbddc->ISForDofs);CHKERRQ(ierr);

  /* allocate space then copy ISs */
  ierr = PetscMalloc(n_is*sizeof(IS),&pcbddc->ISForDofs);CHKERRQ(ierr);
  for(i=0;i<n_is;i++) {
    ierr = ISDuplicate(ISForDofs[i],&pcbddc->ISForDofs[i]);CHKERRQ(ierr);
    ierr = ISCopy(ISForDofs[i],pcbddc->ISForDofs[i]);CHKERRQ(ierr);
  }
  pcbddc->n_ISForDofs=n_is;

  PetscFunctionReturn(0);
}
EXTERN_C_END

/* -------------------------------------------------------------------------- */
#undef __FUNCT__
#define __FUNCT__ "PCBDDCSetDofsSplitting"
/*@
 PCBDDCSetDofsSplitting - Set index set defining how dofs are splitted.

   Not collective

   Input Parameters:
+  pc - the preconditioning context
-  n - number of index sets defining dofs spltting
-  IS[] - array of IS describing dofs splitting

   Level: intermediate

   Notes:
   Sequential ISs are copied, the user must destroy the array of IS passed in.

.seealso: PCBDDC
@*/
PetscErrorCode PCBDDCSetDofsSplitting(PC pc,PetscInt n_is, IS ISForDofs[])
{
  PetscErrorCode ierr;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(pc,PC_CLASSID,1);
  ierr = PetscTryMethod(pc,"PCBDDCSetDofsSplitting_C",(PC,PetscInt,IS[]),(pc,n_is,ISForDofs));CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "PCSetUp_BDDC"
/* -------------------------------------------------------------------------- */
/*
   PCSetUp_BDDC - Prepares for the use of the BDDC preconditioner
                  by setting data structures and options.

   Input Parameter:
+  pc - the preconditioner context

   Application Interface Routine: PCSetUp()

   Notes:
   The interface routine PCSetUp() is not usually called directly by
   the user, but instead is called by PCApply() if necessary.
*/
PetscErrorCode PCSetUp_BDDC(PC pc)
{
  PetscErrorCode ierr;
  PC_BDDC*       pcbddc   = (PC_BDDC*)pc->data;
  PC_IS            *pcis = (PC_IS*)(pc->data);

  PetscFunctionBegin;
  if (!pc->setupcalled) {
    /* For BDDC we need to define a local "Neumann" problem different to that defined in PCISSetup
       So, we set to pcnone the Neumann problem of pcis in order to avoid unneeded computation
       Also, we decide to directly build the (same) Dirichlet problem */
    ierr = PetscOptionsSetValue("-is_localN_pc_type","none");CHKERRQ(ierr);
    ierr = PetscOptionsSetValue("-is_localD_pc_type","none");CHKERRQ(ierr);
    /* Set up all the "iterative substructuring" common block */
    ierr = PCISSetUp(pc);CHKERRQ(ierr);
    /* Get stdout for dbg */
    if(pcbddc->dbg_flag) {
      ierr = PetscViewerASCIIGetStdout(((PetscObject)pc)->comm,&pcbddc->dbg_viewer);CHKERRQ(ierr);
      ierr = PetscViewerASCIISynchronizedAllow(pcbddc->dbg_viewer,PETSC_TRUE);CHKERRQ(ierr);
    }
    /* TODO MOVE CODE FRAGMENT */
    PetscInt im_active=0;
    if(pcis->n) im_active = 1;
    ierr = MPI_Allreduce(&im_active,&pcbddc->active_procs,1,MPIU_INT,MPI_SUM,((PetscObject)pc)->comm);CHKERRQ(ierr);
    /* Analyze local interface */
    ierr = PCBDDCManageLocalBoundaries(pc);CHKERRQ(ierr);
    /* Set up local constraint matrix */
    ierr = PCBDDCCreateConstraintMatrix(pc);CHKERRQ(ierr);
    /* Create coarse and local stuffs used for evaluating action of preconditioner */
    ierr = PCBDDCCoarseSetUp(pc);CHKERRQ(ierr);
    /* Processes fakely involved in multilevel should not call ISLocalToGlobalMappingRestoreInfo */
    if ( !pcis->n_neigh ) pcis->ISLocalToGlobalMappingGetInfoWasCalled=PETSC_FALSE;
  }
  PetscFunctionReturn(0);
}

/* -------------------------------------------------------------------------- */
/*
   PCApply_BDDC - Applies the BDDC preconditioner to a vector.

   Input Parameters:
.  pc - the preconditioner context
.  r - input vector (global)

   Output Parameter:
.  z - output vector (global)

   Application Interface Routine: PCApply()
 */
#undef __FUNCT__
#define __FUNCT__ "PCApply_BDDC"
PetscErrorCode PCApply_BDDC(PC pc,Vec r,Vec z)
{
  PC_IS             *pcis = (PC_IS*)(pc->data);
  PC_BDDC           *pcbddc = (PC_BDDC*)(pc->data);
  PetscErrorCode    ierr;
  const PetscScalar one = 1.0;
  const PetscScalar m_one = -1.0;

/* This code is similar to that provided in nn.c for PCNN
   NN interface preconditioner changed to BDDC
   Added support for M_3 preconditioenr in the reference article (code is active if pcbddc->prec_type = PETSC_TRUE) */

  PetscFunctionBegin;
  /* First Dirichlet solve */
  ierr = VecScatterBegin(pcis->global_to_D,r,pcis->vec1_D,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
  ierr = VecScatterEnd  (pcis->global_to_D,r,pcis->vec1_D,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
  ierr = KSPSolve(pcbddc->ksp_D,pcis->vec1_D,pcis->vec2_D);CHKERRQ(ierr);
  /*
    Assembling right hand side for BDDC operator
    - vec1_D for the Dirichlet part (if needed, i.e. prec_flag=PETSC_TRUE)
    - the interface part of the global vector z
  */
  ierr = VecScale(pcis->vec2_D,m_one);CHKERRQ(ierr);
  ierr = MatMult(pcis->A_BI,pcis->vec2_D,pcis->vec1_B);CHKERRQ(ierr);
  if(pcbddc->prec_type) { ierr = MatMultAdd(pcis->A_II,pcis->vec2_D,pcis->vec1_D,pcis->vec1_D);CHKERRQ(ierr); }
  ierr = VecScale(pcis->vec2_D,m_one);CHKERRQ(ierr);
  ierr = VecCopy(r,z);CHKERRQ(ierr);
  ierr = VecScatterBegin(pcis->global_to_B,pcis->vec1_B,z,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
  ierr = VecScatterEnd  (pcis->global_to_B,pcis->vec1_B,z,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);

  /*
    Apply interface preconditioner
    Results are stored in:
    -  vec1_D (if needed, i.e. with prec_type = PETSC_TRUE)
    -  the interface part of the global vector z
  */
  ierr = PCBDDCApplyInterfacePreconditioner(pc,z);CHKERRQ(ierr);

  /* Second Dirichlet solve and assembling of output */
  ierr = VecScatterBegin(pcis->global_to_B,z,pcis->vec1_B,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
  ierr = VecScatterEnd  (pcis->global_to_B,z,pcis->vec1_B,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
  ierr = MatMult(pcis->A_IB,pcis->vec1_B,pcis->vec3_D);CHKERRQ(ierr);
  if(pcbddc->prec_type) { ierr = MatMultAdd(pcis->A_II,pcis->vec1_D,pcis->vec3_D,pcis->vec3_D);CHKERRQ(ierr); }
  ierr = KSPSolve(pcbddc->ksp_D,pcis->vec3_D,pcbddc->vec4_D);CHKERRQ(ierr);
  ierr = VecScale(pcbddc->vec4_D,m_one);CHKERRQ(ierr);
  if(pcbddc->prec_type) { ierr = VecAXPY (pcbddc->vec4_D,one,pcis->vec1_D);CHKERRQ(ierr); }
  ierr = VecAXPY (pcis->vec2_D,one,pcbddc->vec4_D);CHKERRQ(ierr);
  ierr = VecScatterBegin(pcis->global_to_D,pcis->vec2_D,z,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
  ierr = VecScatterEnd  (pcis->global_to_D,pcis->vec2_D,z,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);

  PetscFunctionReturn(0);

}

/* -------------------------------------------------------------------------- */
/*
   PCBDDCApplyInterfacePreconditioner - Apply the BDDC preconditioner at the interface.

*/
#undef __FUNCT__
#define __FUNCT__ "PCBDDCApplyInterfacePreconditioner"
static PetscErrorCode  PCBDDCApplyInterfacePreconditioner(PC pc, Vec z)
{
  PetscErrorCode ierr;
  PC_BDDC*        pcbddc = (PC_BDDC*)(pc->data);
  PC_IS*            pcis = (PC_IS*)  (pc->data);
  const PetscScalar zero = 0.0;

  PetscFunctionBegin;
  /* Get Local boundary and apply partition of unity */
  ierr = VecScatterBegin(pcis->global_to_B,z,pcis->vec1_B,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
  ierr = VecScatterEnd  (pcis->global_to_B,z,pcis->vec1_B,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
  ierr = VecPointwiseMult(pcis->vec1_B,pcis->D,pcis->vec1_B);CHKERRQ(ierr);

  /* Application of PHI^T  */
  ierr = MatMultTranspose(pcbddc->coarse_phi_B,pcis->vec1_B,pcbddc->vec1_P);CHKERRQ(ierr);
  if(pcbddc->prec_type) { ierr = MatMultTransposeAdd(pcbddc->coarse_phi_D,pcis->vec1_D,pcbddc->vec1_P,pcbddc->vec1_P);CHKERRQ(ierr); }

  /* Scatter data of coarse_rhs */
  if(pcbddc->coarse_rhs) ierr = VecSet(pcbddc->coarse_rhs,zero);CHKERRQ(ierr);
  ierr = PCBDDCScatterCoarseDataBegin(pc,pcbddc->vec1_P,pcbddc->coarse_rhs,ADD_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);

  /* Local solution on R nodes */
  ierr = VecSet(pcbddc->vec1_R,zero);CHKERRQ(ierr);
  ierr = VecScatterBegin(pcbddc->R_to_B,pcis->vec1_B,pcbddc->vec1_R,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
  ierr = VecScatterEnd  (pcbddc->R_to_B,pcis->vec1_B,pcbddc->vec1_R,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
  if(pcbddc->prec_type) {
    ierr = VecScatterBegin(pcbddc->R_to_D,pcis->vec1_D,pcbddc->vec1_R,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
    ierr = VecScatterEnd  (pcbddc->R_to_D,pcis->vec1_D,pcbddc->vec1_R,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
  }
  ierr = PCBDDCSolveSaddlePoint(pc);CHKERRQ(ierr);
  ierr = VecSet(pcis->vec1_B,zero);CHKERRQ(ierr);
  ierr = VecScatterBegin(pcbddc->R_to_B,pcbddc->vec2_R,pcis->vec1_B,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
  ierr = VecScatterEnd  (pcbddc->R_to_B,pcbddc->vec2_R,pcis->vec1_B,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
  if(pcbddc->prec_type) {
    ierr = VecScatterBegin(pcbddc->R_to_D,pcbddc->vec2_R,pcis->vec1_D,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
    ierr = VecScatterEnd  (pcbddc->R_to_D,pcbddc->vec2_R,pcis->vec1_D,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
  }

  /* Coarse solution */
  ierr = PCBDDCScatterCoarseDataEnd(pc,pcbddc->vec1_P,pcbddc->coarse_rhs,ADD_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
  if(pcbddc->coarse_rhs) ierr = KSPSolve(pcbddc->coarse_ksp,pcbddc->coarse_rhs,pcbddc->coarse_vec);CHKERRQ(ierr);
  ierr = PCBDDCScatterCoarseDataBegin(pc,pcbddc->coarse_vec,pcbddc->vec1_P,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
  ierr = PCBDDCScatterCoarseDataEnd  (pc,pcbddc->coarse_vec,pcbddc->vec1_P,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);

  /* Sum contributions from two levels */
  /* Apply partition of unity and sum boundary values */
  ierr = MatMultAdd(pcbddc->coarse_phi_B,pcbddc->vec1_P,pcis->vec1_B,pcis->vec1_B);CHKERRQ(ierr);
  ierr = VecPointwiseMult(pcis->vec1_B,pcis->D,pcis->vec1_B);CHKERRQ(ierr);
  if(pcbddc->prec_type) { ierr = MatMultAdd(pcbddc->coarse_phi_D,pcbddc->vec1_P,pcis->vec1_D,pcis->vec1_D);CHKERRQ(ierr); }
  ierr = VecSet(z,zero);CHKERRQ(ierr);
  ierr = VecScatterBegin(pcis->global_to_B,pcis->vec1_B,z,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
  ierr = VecScatterEnd  (pcis->global_to_B,pcis->vec1_B,z,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);

  PetscFunctionReturn(0);
}


/* -------------------------------------------------------------------------- */
/*
   PCBDDCSolveSaddlePoint

*/
#undef __FUNCT__
#define __FUNCT__ "PCBDDCSolveSaddlePoint"
static PetscErrorCode  PCBDDCSolveSaddlePoint(PC pc)
{
  PetscErrorCode ierr;
  PC_BDDC*       pcbddc = (PC_BDDC*)(pc->data);

  PetscFunctionBegin;

  ierr = KSPSolve(pcbddc->ksp_R,pcbddc->vec1_R,pcbddc->vec2_R);CHKERRQ(ierr);
  if(pcbddc->n_constraints) {
    ierr = MatMult(pcbddc->local_auxmat1,pcbddc->vec2_R,pcbddc->vec1_C);CHKERRQ(ierr);
    ierr = MatMultAdd(pcbddc->local_auxmat2,pcbddc->vec1_C,pcbddc->vec2_R,pcbddc->vec2_R);CHKERRQ(ierr);
  }

  PetscFunctionReturn(0);
}
/* -------------------------------------------------------------------------- */
/*
   PCBDDCScatterCoarseDataBegin

*/
#undef __FUNCT__
#define __FUNCT__ "PCBDDCScatterCoarseDataBegin"
static PetscErrorCode  PCBDDCScatterCoarseDataBegin(PC pc,Vec vec_from, Vec vec_to, InsertMode imode, ScatterMode smode)
{
  PetscErrorCode ierr;
  PC_BDDC*       pcbddc = (PC_BDDC*)(pc->data);

  PetscFunctionBegin;

  switch(pcbddc->coarse_communications_type){
    case SCATTERS_BDDC:
      ierr = VecScatterBegin(pcbddc->coarse_loc_to_glob,vec_from,vec_to,imode,smode);CHKERRQ(ierr);
      break;
    case GATHERS_BDDC:
      break;
  }
  PetscFunctionReturn(0);

}
/* -------------------------------------------------------------------------- */
/*
   PCBDDCScatterCoarseDataEnd

*/
#undef __FUNCT__
#define __FUNCT__ "PCBDDCScatterCoarseDataEnd"
static PetscErrorCode  PCBDDCScatterCoarseDataEnd(PC pc,Vec vec_from, Vec vec_to, InsertMode imode, ScatterMode smode)
{
  PetscErrorCode ierr;
  PC_BDDC*       pcbddc = (PC_BDDC*)(pc->data);
  PetscScalar*   array_to;
  PetscScalar*   array_from;
  MPI_Comm       comm=((PetscObject)pc)->comm;
  PetscInt i;

  PetscFunctionBegin;

  switch(pcbddc->coarse_communications_type){
    case SCATTERS_BDDC:
      ierr = VecScatterEnd(pcbddc->coarse_loc_to_glob,vec_from,vec_to,imode,smode);CHKERRQ(ierr);
      break;
    case GATHERS_BDDC:
      if(vec_from) VecGetArray(vec_from,&array_from);
      if(vec_to)   VecGetArray(vec_to,&array_to);
      switch(pcbddc->coarse_problem_type){
        case SEQUENTIAL_BDDC:
          if(smode == SCATTER_FORWARD) {
            ierr = MPI_Gatherv(&array_from[0],pcbddc->local_primal_size,MPIU_SCALAR,&pcbddc->replicated_local_primal_values[0],pcbddc->local_primal_sizes,pcbddc->local_primal_displacements,MPIU_SCALAR,0,comm);CHKERRQ(ierr);
            if(vec_to) {
              for(i=0;i<pcbddc->replicated_primal_size;i++)
                array_to[pcbddc->replicated_local_primal_indices[i]]+=pcbddc->replicated_local_primal_values[i];
            }
          } else {
            if(vec_from)
              for(i=0;i<pcbddc->replicated_primal_size;i++)
                pcbddc->replicated_local_primal_values[i]=array_from[pcbddc->replicated_local_primal_indices[i]];
            ierr = MPI_Scatterv(&pcbddc->replicated_local_primal_values[0],pcbddc->local_primal_sizes,pcbddc->local_primal_displacements,MPIU_SCALAR,&array_to[0],pcbddc->local_primal_size,MPIU_SCALAR,0,comm);CHKERRQ(ierr);
          }
          break;
        case REPLICATED_BDDC:
          if(smode == SCATTER_FORWARD) {
            ierr = MPI_Allgatherv(&array_from[0],pcbddc->local_primal_size,MPIU_SCALAR,&pcbddc->replicated_local_primal_values[0],pcbddc->local_primal_sizes,pcbddc->local_primal_displacements,MPIU_SCALAR,comm);CHKERRQ(ierr);
            for(i=0;i<pcbddc->replicated_primal_size;i++)
              array_to[pcbddc->replicated_local_primal_indices[i]]+=pcbddc->replicated_local_primal_values[i];
          } else { /* no communications needed for SCATTER_REVERSE since needed data is already present */
            for(i=0;i<pcbddc->local_primal_size;i++)
              array_to[i]=array_from[pcbddc->local_primal_indices[i]];
          }
          break;
        case MULTILEVEL_BDDC:
          break;
        case PARALLEL_BDDC:
          break;
      }
      if(vec_from) VecRestoreArray(vec_from,&array_from);
      if(vec_to)   VecRestoreArray(vec_to,&array_to);
      break;
  }
  PetscFunctionReturn(0);

}

/* -------------------------------------------------------------------------- */
/*
   PCDestroy_BDDC - Destroys the private context for the NN preconditioner
   that was created with PCCreate_BDDC().

   Input Parameter:
.  pc - the preconditioner context

   Application Interface Routine: PCDestroy()
*/
#undef __FUNCT__
#define __FUNCT__ "PCDestroy_BDDC"
PetscErrorCode PCDestroy_BDDC(PC pc)
{
  PC_BDDC          *pcbddc = (PC_BDDC*)pc->data;
  PetscErrorCode ierr;

  PetscFunctionBegin;
  /* free data created by PCIS */
  ierr = PCISDestroy(pc);CHKERRQ(ierr);
  /* free BDDC data  */
  ierr = VecDestroy(&pcbddc->coarse_vec);CHKERRQ(ierr);
  ierr = VecDestroy(&pcbddc->coarse_rhs);CHKERRQ(ierr);
  ierr = KSPDestroy(&pcbddc->coarse_ksp);CHKERRQ(ierr);
  ierr = MatDestroy(&pcbddc->coarse_mat);CHKERRQ(ierr);
  ierr = MatDestroy(&pcbddc->coarse_phi_B);CHKERRQ(ierr);
  ierr = MatDestroy(&pcbddc->coarse_phi_D);CHKERRQ(ierr);
  ierr = VecDestroy(&pcbddc->vec1_P);CHKERRQ(ierr);
  ierr = VecDestroy(&pcbddc->vec1_C);CHKERRQ(ierr);
  ierr = MatDestroy(&pcbddc->local_auxmat1);CHKERRQ(ierr);
  ierr = MatDestroy(&pcbddc->local_auxmat2);CHKERRQ(ierr);
  ierr = VecDestroy(&pcbddc->vec1_R);CHKERRQ(ierr);
  ierr = VecDestroy(&pcbddc->vec2_R);CHKERRQ(ierr);
  ierr = VecDestroy(&pcbddc->vec4_D);CHKERRQ(ierr);
  ierr = VecScatterDestroy(&pcbddc->R_to_B);CHKERRQ(ierr);
  ierr = VecScatterDestroy(&pcbddc->R_to_D);CHKERRQ(ierr);
  ierr = VecScatterDestroy(&pcbddc->coarse_loc_to_glob);CHKERRQ(ierr);
  ierr = KSPDestroy(&pcbddc->ksp_D);CHKERRQ(ierr);
  ierr = KSPDestroy(&pcbddc->ksp_R);CHKERRQ(ierr);
  ierr = ISDestroy(&pcbddc->NeumannBoundaries);CHKERRQ(ierr);
  ierr = ISDestroy(&pcbddc->DirichletBoundaries);CHKERRQ(ierr);
  ierr = MatDestroy(&pcbddc->ConstraintMatrix);CHKERRQ(ierr);
  ierr = PetscFree(pcbddc->local_primal_indices);CHKERRQ(ierr);
  ierr = PetscFree(pcbddc->replicated_local_primal_indices);CHKERRQ(ierr);
  if (pcbddc->replicated_local_primal_values)    { free(pcbddc->replicated_local_primal_values); }
  ierr = PetscFree(pcbddc->local_primal_displacements);CHKERRQ(ierr);
  ierr = PetscFree(pcbddc->local_primal_sizes);CHKERRQ(ierr);
  PetscInt i;
  for(i=0;i<pcbddc->n_ISForDofs;i++) { ierr = ISDestroy(&pcbddc->ISForDofs[i]);CHKERRQ(ierr); }
  ierr = PetscFree(pcbddc->ISForDofs);CHKERRQ(ierr);
  for(i=0;i<pcbddc->n_ISForFaces;i++) { ierr = ISDestroy(&pcbddc->ISForFaces[i]);CHKERRQ(ierr); }
  ierr = PetscFree(pcbddc->ISForFaces);CHKERRQ(ierr);
  for(i=0;i<pcbddc->n_ISForEdges;i++) { ierr = ISDestroy(&pcbddc->ISForEdges[i]);CHKERRQ(ierr); }
  ierr = PetscFree(pcbddc->ISForEdges);CHKERRQ(ierr);
  ierr = ISDestroy(&pcbddc->ISForVertices);CHKERRQ(ierr);
  /* Free the private data structure that was hanging off the PC */
  ierr = PetscFree(pcbddc);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

/* -------------------------------------------------------------------------- */
/*MC
   PCBDDC - Balancing Domain Decomposition by Constraints.

   Options Database Keys:
.    -pcbddc ??? -

   Level: intermediate

   Notes: The matrix used with this preconditioner must be of type MATIS

          Unlike more 'conventional' interface preconditioners, this iterates over ALL the
          degrees of freedom, NOT just those on the interface (this allows the use of approximate solvers
          on the subdomains).

          Options for the coarse grid preconditioner can be set with -
          Options for the Dirichlet subproblem can be set with -
          Options for the Neumann subproblem can be set with -

   Contributed by Stefano Zampini

.seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PC,  MATIS
M*/
EXTERN_C_BEGIN
#undef __FUNCT__
#define __FUNCT__ "PCCreate_BDDC"
PetscErrorCode PCCreate_BDDC(PC pc)
{
  PetscErrorCode ierr;
  PC_BDDC          *pcbddc;

  PetscFunctionBegin;
  /* Creates the private data structure for this preconditioner and attach it to the PC object. */
  ierr      = PetscNewLog(pc,PC_BDDC,&pcbddc);CHKERRQ(ierr);
  pc->data  = (void*)pcbddc;
  /* create PCIS data structure */
  ierr = PCISCreate(pc);CHKERRQ(ierr);
  /* BDDC specific */
  pcbddc->coarse_vec                 = 0;
  pcbddc->coarse_rhs                 = 0;
  pcbddc->coarse_ksp                 = 0;
  pcbddc->coarse_phi_B               = 0;
  pcbddc->coarse_phi_D               = 0;
  pcbddc->vec1_P                     = 0;
  pcbddc->vec1_R                     = 0;
  pcbddc->vec2_R                     = 0;
  pcbddc->local_auxmat1              = 0;
  pcbddc->local_auxmat2              = 0;
  pcbddc->R_to_B                     = 0;
  pcbddc->R_to_D                     = 0;
  pcbddc->ksp_D                      = 0;
  pcbddc->ksp_R                      = 0;
  pcbddc->local_primal_indices       = 0;
  pcbddc->prec_type                  = PETSC_FALSE;
  pcbddc->NeumannBoundaries          = 0;
  pcbddc->ISForDofs                  = 0;
  pcbddc->ISForVertices              = 0;
  pcbddc->n_ISForFaces               = 0;
  pcbddc->n_ISForEdges               = 0;
  pcbddc->ConstraintMatrix           = 0;
  pcbddc->use_nnsp_true              = PETSC_FALSE;
  pcbddc->local_primal_sizes         = 0;
  pcbddc->local_primal_displacements = 0;
  pcbddc->replicated_local_primal_indices = 0;
  pcbddc->replicated_local_primal_values  = 0;
  pcbddc->coarse_loc_to_glob         = 0;
  pcbddc->dbg_flag                   = PETSC_FALSE;
  pcbddc->coarsening_ratio           = 8;
  /* function pointers */
  pc->ops->apply               = PCApply_BDDC;
  pc->ops->applytranspose      = 0;
  pc->ops->setup               = PCSetUp_BDDC;
  pc->ops->destroy             = PCDestroy_BDDC;
  pc->ops->setfromoptions      = PCSetFromOptions_BDDC;
  pc->ops->view                = 0;
  pc->ops->applyrichardson     = 0;
  pc->ops->applysymmetricleft  = 0;
  pc->ops->applysymmetricright = 0;
  /* composing function */
  ierr = PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCBDDCSetDirichletBoundaries_C","PCBDDCSetDirichletBoundaries_BDDC",
                    PCBDDCSetDirichletBoundaries_BDDC);CHKERRQ(ierr);
  ierr = PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCBDDCSetNeumannBoundaries_C","PCBDDCSetNeumannBoundaries_BDDC",
                    PCBDDCSetNeumannBoundaries_BDDC);CHKERRQ(ierr);
  ierr = PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCBDDCGetDirichletBoundaries_C","PCBDDCGetDirichletBoundaries_BDDC",
                    PCBDDCGetDirichletBoundaries_BDDC);CHKERRQ(ierr);
  ierr = PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCBDDCGetNeumannBoundaries_C","PCBDDCGetNeumannBoundaries_BDDC",
                    PCBDDCGetNeumannBoundaries_BDDC);CHKERRQ(ierr);
  ierr = PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCBDDCSetCoarseProblemType_C","PCBDDCSetCoarseProblemType_BDDC",
                    PCBDDCSetCoarseProblemType_BDDC);CHKERRQ(ierr);
  ierr = PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCBDDCSetDofsSplitting_C","PCBDDCSetDofsSplitting_BDDC",
                    PCBDDCSetDofsSplitting_BDDC);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}
EXTERN_C_END

/* -------------------------------------------------------------------------- */
/*
   Create C matrix [I 0; 0 const]
*/
#ifdef BDDC_USE_POD
#if !defined(PETSC_MISSING_LAPACK_GESVD)
#define PETSC_MISSING_LAPACK_GESVD 1
#define UNDEF_PETSC_MISSING_LAPACK_GESVD 1
#endif
#endif

#undef __FUNCT__
#define __FUNCT__ "PCBDDCCreateConstraintMatrix"
static PetscErrorCode PCBDDCCreateConstraintMatrix(PC pc)
{
  PetscErrorCode ierr;
  PC_IS*         pcis = (PC_IS*)(pc->data);
  PC_BDDC*       pcbddc = (PC_BDDC*)pc->data;
  Mat_IS         *matis = (Mat_IS*)pc->pmat->data;
  PetscInt       *nnz,*vertices,*is_indices;
  PetscScalar    *temp_quadrature_constraint;
  PetscInt       *temp_indices,*temp_indices_to_constraint;
  PetscInt       local_primal_size,i,j,k,total_counts,max_size_of_constraint;
  PetscInt       n_constraints,n_vertices,size_of_constraint;
  PetscReal      quad_value;
  PetscBool      nnsp_has_cnst=PETSC_FALSE,use_nnsp_true=pcbddc->use_nnsp_true;
  PetscInt       nnsp_size=0,nnsp_addone=0,temp_constraints,temp_start_ptr;
  IS             *used_IS;
  const MatType  impMatType=MATSEQAIJ;
  PetscBLASInt   Bs,Bt,lwork,lierr;
  PetscReal      tol=1.0e-8;
  MatNullSpace   nearnullsp;
  const Vec      *nearnullvecs;
  Vec            *localnearnullsp;
  PetscScalar    *work,*temp_basis,*array_vector,*correlation_mat;
  PetscReal      *rwork,*singular_vals;
  PetscBLASInt   Bone=1;
/* some ugly conditional declarations */
#if defined(PETSC_MISSING_LAPACK_GESVD)
  PetscScalar    dot_result;
  PetscScalar    one=1.0,zero=0.0;
  PetscInt       ii;
#if defined(PETSC_USE_COMPLEX)
  PetscScalar    val1,val2;
#endif
#else
  PetscBLASInt   dummy_int;
  PetscScalar    dummy_scalar;
#endif

  PetscFunctionBegin;
  /* check if near null space is attached to global mat */
  ierr = MatGetNearNullSpace(pc->pmat,&nearnullsp);CHKERRQ(ierr);
  if (nearnullsp) {
    ierr = MatNullSpaceGetVecs(nearnullsp,&nnsp_has_cnst,&nnsp_size,&nearnullvecs);CHKERRQ(ierr);
  } else { /* if near null space is not provided it uses constants */
    nnsp_has_cnst = PETSC_TRUE;
    use_nnsp_true = PETSC_TRUE;
  }
  if(nnsp_has_cnst) {
    nnsp_addone = 1;
  }
  /*
       Evaluate maximum storage size needed by the procedure
       - temp_indices will contain start index of each constraint stored as follows
       - temp_indices_to_constraint[temp_indices[i],...,temp[indices[i+1]-1] will contain the indices (in local numbering) on which the constraint acts
       - temp_quadrature_constraint[temp_indices[i],...,temp[indices[i+1]-1] will contain the scalars representing the constraint itself
                                                                                                                                                         */
  total_counts = pcbddc->n_ISForFaces+pcbddc->n_ISForEdges;
  total_counts *= (nnsp_addone+nnsp_size);
  ierr = PetscMalloc((total_counts+1)*sizeof(PetscInt),&temp_indices);CHKERRQ(ierr);
  total_counts = 0;
  max_size_of_constraint = 0;
  for(i=0;i<pcbddc->n_ISForEdges+pcbddc->n_ISForFaces;i++){
    if(i<pcbddc->n_ISForEdges){
      used_IS = &pcbddc->ISForEdges[i];
    } else {
      used_IS = &pcbddc->ISForFaces[i-pcbddc->n_ISForEdges];
    }
    ierr = ISGetSize(*used_IS,&j);CHKERRQ(ierr);
    total_counts += j;
    if(j>max_size_of_constraint) max_size_of_constraint=j;
  }
  total_counts *= (nnsp_addone+nnsp_size);
  ierr = PetscMalloc(total_counts*sizeof(PetscScalar),&temp_quadrature_constraint);CHKERRQ(ierr);
  ierr = PetscMalloc(total_counts*sizeof(PetscInt),&temp_indices_to_constraint);CHKERRQ(ierr);
  /* First we issue queries to allocate optimal workspace for LAPACKgesvd or LAPACKsyev/LAPACKheev */
  rwork = 0;
  work = 0;
  singular_vals = 0;
  temp_basis = 0;
  correlation_mat = 0;
  if(!pcbddc->use_nnsp_true) {
    PetscScalar temp_work;
#if defined(PETSC_MISSING_LAPACK_GESVD)
    /* POD */
    PetscInt max_n;
    max_n = nnsp_addone+nnsp_size;
    /* using some techniques borrowed from Proper Orthogonal Decomposition */
    ierr = PetscMalloc(max_n*max_n*sizeof(PetscScalar),&correlation_mat);CHKERRQ(ierr);
    ierr = PetscMalloc(max_n*sizeof(PetscReal),&singular_vals);CHKERRQ(ierr);
    ierr = PetscMalloc(max_size_of_constraint*(nnsp_addone+nnsp_size)*sizeof(PetscScalar),&temp_basis);CHKERRQ(ierr);
#if defined(PETSC_USE_COMPLEX)
    ierr = PetscMalloc(3*max_n*sizeof(PetscReal),&rwork);CHKERRQ(ierr);
#endif
    /* now we evaluate the optimal workspace using query with lwork=-1 */
    Bt = PetscBLASIntCast(max_n);
    lwork=-1;
#if !defined(PETSC_USE_COMPLEX)
    LAPACKsyev_("V","U",&Bt,correlation_mat,&Bt,singular_vals,&temp_work,&lwork,&lierr);
#else
    LAPACKsyev_("V","U",&Bt,correlation_mat,&Bt,singular_vals,&temp_work,&lwork,rwork,&lierr);
#endif
#else /* on missing GESVD */
    /* SVD */
    PetscInt max_n,min_n;
    max_n = max_size_of_constraint;
    min_n = nnsp_addone+nnsp_size;
    if(max_size_of_constraint < ( nnsp_addone+nnsp_size ) ) {
      min_n = max_size_of_constraint;
      max_n = nnsp_addone+nnsp_size;
    }
    ierr = PetscMalloc(min_n*sizeof(PetscReal),&singular_vals);CHKERRQ(ierr);
#if defined(PETSC_USE_COMPLEX)
    ierr = PetscMalloc(5*min_n*sizeof(PetscReal),&rwork);CHKERRQ(ierr);
#endif
    /* now we evaluate the optimal workspace using query with lwork=-1 */
    lwork=-1;
    Bs = PetscBLASIntCast(max_n);
    Bt = PetscBLASIntCast(min_n);
    dummy_int = Bs;
    ierr = PetscFPTrapPush(PETSC_FP_TRAP_OFF);CHKERRQ(ierr);
#if !defined(PETSC_USE_COMPLEX)
    LAPACKgesvd_("O","N",&Bs,&Bt,&temp_quadrature_constraint[0],&Bs,singular_vals,
                 &dummy_scalar,&dummy_int,&dummy_scalar,&dummy_int,&temp_work,&lwork,&lierr);
#else
    LAPACKgesvd_("O","N",&Bs,&Bt,&temp_quadrature_constraint[0],&Bs,singular_vals,
                 &dummy_scalar,&dummy_int,&dummy_scalar,&dummy_int,&temp_work,&lwork,rwork,&lierr);
#endif
    if ( lierr ) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in query to SVD Lapack routine %d",(int)lierr);
    ierr = PetscFPTrapPop();CHKERRQ(ierr);
#endif
    /* Allocate optimal workspace */
    lwork = PetscBLASIntCast((PetscInt)PetscRealPart(temp_work));
    total_counts = (PetscInt)lwork;
    ierr = PetscMalloc(total_counts*sizeof(PetscScalar),&work);CHKERRQ(ierr);
  }
  /* get local part of global near null space vectors */
  ierr = PetscMalloc(nnsp_size*sizeof(Vec),&localnearnullsp);CHKERRQ(ierr);
  for(k=0;k<nnsp_size;k++) {
    ierr = VecDuplicate(pcis->vec1_N,&localnearnullsp[k]);CHKERRQ(ierr);
    ierr = VecScatterBegin(matis->ctx,nearnullvecs[k],localnearnullsp[k],INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
    ierr = VecScatterEnd  (matis->ctx,nearnullvecs[k],localnearnullsp[k],INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
  }
  /* Now we can loop on constraining sets */
  total_counts=0;
  temp_indices[0]=0;
  for(i=0;i<pcbddc->n_ISForEdges+pcbddc->n_ISForFaces;i++){
    if(i<pcbddc->n_ISForEdges){
      used_IS = &pcbddc->ISForEdges[i];
    } else {
      used_IS = &pcbddc->ISForFaces[i-pcbddc->n_ISForEdges];
    }
    temp_constraints = 0;          /* zero the number of constraints I have on this conn comp */
    temp_start_ptr = total_counts; /* need to know the starting index of constraints stored */
    ierr = ISGetSize(*used_IS,&size_of_constraint);CHKERRQ(ierr);
    ierr = ISGetIndices(*used_IS,(const PetscInt**)&is_indices);CHKERRQ(ierr);
    if(nnsp_has_cnst) {
      temp_constraints++;
      quad_value = 1.0/PetscSqrtReal((PetscReal)size_of_constraint);
      for(j=0;j<size_of_constraint;j++) {
        temp_indices_to_constraint[temp_indices[total_counts]+j]=is_indices[j];
        temp_quadrature_constraint[temp_indices[total_counts]+j]=quad_value;
      }
      temp_indices[total_counts+1]=temp_indices[total_counts]+size_of_constraint;  /* store new starting point */
      total_counts++;
    }
    for(k=0;k<nnsp_size;k++) {
      ierr = VecGetArrayRead(localnearnullsp[k],(const PetscScalar**)&array_vector);CHKERRQ(ierr);
      for(j=0;j<size_of_constraint;j++) {
        temp_indices_to_constraint[temp_indices[total_counts]+j]=is_indices[j];
        temp_quadrature_constraint[temp_indices[total_counts]+j]=array_vector[is_indices[j]];
      }
      ierr = VecRestoreArrayRead(localnearnullsp[k],(const PetscScalar**)&array_vector);CHKERRQ(ierr);
      quad_value = 1.0;
      if( use_nnsp_true ) { /* check if array is null on the connected component in case use_nnsp_true has been requested */
        Bs = PetscBLASIntCast(size_of_constraint);
        quad_value = BLASasum_(&Bs,&temp_quadrature_constraint[temp_indices[total_counts]],&Bone);
      }
      if ( quad_value > 0.0 ) { /* keep indices and values */
        temp_constraints++;
        temp_indices[total_counts+1]=temp_indices[total_counts]+size_of_constraint;  /* store new starting point */
        total_counts++;
      }
    }
    ierr = ISRestoreIndices(*used_IS,(const PetscInt**)&is_indices);CHKERRQ(ierr);
    /* perform SVD on the constraint if use_nnsp_true has not be requested by the user */
    if(!use_nnsp_true) {

      Bs = PetscBLASIntCast(size_of_constraint);
      Bt = PetscBLASIntCast(temp_constraints);

#if defined(PETSC_MISSING_LAPACK_GESVD)
      ierr = PetscMemzero(correlation_mat,Bt*Bt*sizeof(PetscScalar));CHKERRQ(ierr);
      /* Store upper triangular part of correlation matrix */
      for(j=0;j<temp_constraints;j++) {
        for(k=0;k<j+1;k++) {
#if defined(PETSC_USE_COMPLEX)
          /* hand made complex dot product */
          dot_result = 0.0;
          for (ii=0; ii<size_of_constraint; ii++) {
            val1 = temp_quadrature_constraint[temp_indices[temp_start_ptr+j]+ii];
            val2 = temp_quadrature_constraint[temp_indices[temp_start_ptr+k]+ii];
            dot_result += val1*PetscConj(val2);
          }
#else
          dot_result = BLASdot_(&Bs,&temp_quadrature_constraint[temp_indices[temp_start_ptr+j]],&Bone,
                                    &temp_quadrature_constraint[temp_indices[temp_start_ptr+k]],&Bone);
#endif
          correlation_mat[j*temp_constraints+k]=dot_result;
        }
      }
#if !defined(PETSC_USE_COMPLEX)
      LAPACKsyev_("V","U",&Bt,correlation_mat,&Bt,singular_vals,work,&lwork,&lierr);
#else
      LAPACKsyev_("V","U",&Bt,correlation_mat,&Bt,singular_vals,work,&lwork,rwork,&lierr);
#endif
      if ( lierr ) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in EV Lapack routine %d",(int)lierr);
      /* retain eigenvalues greater than tol: note that lapack SYEV gives eigs in ascending order */
      j=0;
      while( j < Bt && singular_vals[j] < tol) j++;
      total_counts=total_counts-j;
      if(j<temp_constraints) {
        for(k=j;k<Bt;k++) { singular_vals[k]=1.0/PetscSqrtReal(singular_vals[k]); }
        BLASgemm_("N","N",&Bs,&Bt,&Bt,&one,&temp_quadrature_constraint[temp_indices[temp_start_ptr]],&Bs,correlation_mat,&Bt,&zero,temp_basis,&Bs);
        /* copy POD basis into used quadrature memory */
        for(k=0;k<Bt-j;k++) {
          for(ii=0;ii<size_of_constraint;ii++) {
            temp_quadrature_constraint[temp_indices[temp_start_ptr+k]+ii]=singular_vals[Bt-1-k]*temp_basis[(Bt-1-k)*size_of_constraint+ii];
          }
        }
      }

#else  /* on missing GESVD */

      PetscInt min_n = temp_constraints;
      if(min_n > size_of_constraint) min_n = size_of_constraint;
      dummy_int = Bs;
      ierr = PetscFPTrapPush(PETSC_FP_TRAP_OFF);CHKERRQ(ierr);
#if !defined(PETSC_USE_COMPLEX)
      LAPACKgesvd_("O","N",&Bs,&Bt,&temp_quadrature_constraint[temp_indices[temp_start_ptr]],&Bs,singular_vals,
                   &dummy_scalar,&dummy_int,&dummy_scalar,&dummy_int,work,&lwork,&lierr);
#else
      LAPACKgesvd_("O","N",&Bs,&Bt,&temp_quadrature_constraint[temp_indices[temp_start_ptr]],&Bs,singular_vals,
                   &dummy_scalar,&dummy_int,&dummy_scalar,&dummy_int,work,&lwork,rwork,&lierr);
#endif
      if ( lierr ) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in SVD Lapack routine %d",(int)lierr);
      ierr = PetscFPTrapPop();CHKERRQ(ierr);
      /* retain eigenvalues greater than tol: note that lapack SVD gives eigs in descending order */
      j=0;
      while( j < min_n && singular_vals[min_n-j-1] < tol) j++;
      total_counts = total_counts-(PetscInt)Bt+(min_n-j);

#endif
    }
  }
  n_constraints=total_counts;
  ierr = ISGetSize(pcbddc->ISForVertices,&n_vertices);CHKERRQ(ierr);
  local_primal_size = n_vertices+n_constraints;
  ierr = PetscMalloc(local_primal_size*sizeof(PetscInt),&nnz);CHKERRQ(ierr);
  ierr = MatCreate(PETSC_COMM_SELF,&pcbddc->ConstraintMatrix);CHKERRQ(ierr);
  ierr = MatSetType(pcbddc->ConstraintMatrix,impMatType);CHKERRQ(ierr);
  ierr = MatSetSizes(pcbddc->ConstraintMatrix,local_primal_size,pcis->n,local_primal_size,pcis->n);CHKERRQ(ierr);
  for(i=0;i<n_vertices;i++) { nnz[i]= 1; }
  for(i=0;i<n_constraints;i++) { nnz[i+n_vertices]=temp_indices[i+1]-temp_indices[i]; }
  ierr = MatSeqAIJSetPreallocation(pcbddc->ConstraintMatrix,0,nnz);CHKERRQ(ierr);
  ierr = ISGetIndices(pcbddc->ISForVertices,(const PetscInt**)&vertices);CHKERRQ(ierr);
  for(i=0;i<n_vertices;i++) { ierr = MatSetValue(pcbddc->ConstraintMatrix,i,vertices[i],1.0,INSERT_VALUES);CHKERRQ(ierr); }
  ierr = ISRestoreIndices(pcbddc->ISForVertices,(const PetscInt**)&vertices);CHKERRQ(ierr);
  for(i=0;i<n_constraints;i++) {
    j=i+n_vertices;
    size_of_constraint=temp_indices[i+1]-temp_indices[i];
    ierr = MatSetValues(pcbddc->ConstraintMatrix,1,&j,size_of_constraint,&temp_indices_to_constraint[temp_indices[i]],&temp_quadrature_constraint[temp_indices[i]],INSERT_VALUES);CHKERRQ(ierr);
  }
  ierr = MatAssemblyBegin(pcbddc->ConstraintMatrix,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
  ierr = MatAssemblyEnd(pcbddc->ConstraintMatrix,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
  /* set quantities in pcbddc data structure */
  pcbddc->n_vertices = n_vertices;
  pcbddc->n_constraints = n_constraints;
  pcbddc->local_primal_size = n_vertices+n_constraints;
  /* free workspace no longer needed */
  ierr = PetscFree(rwork);CHKERRQ(ierr);
  ierr = PetscFree(work);CHKERRQ(ierr);
  ierr = PetscFree(temp_basis);CHKERRQ(ierr);
  ierr = PetscFree(singular_vals);CHKERRQ(ierr);
  ierr = PetscFree(correlation_mat);CHKERRQ(ierr);
  ierr = PetscFree(temp_indices);CHKERRQ(ierr);
  ierr = PetscFree(temp_indices_to_constraint);CHKERRQ(ierr);
  ierr = PetscFree(temp_quadrature_constraint);CHKERRQ(ierr);
  ierr = PetscFree(nnz);CHKERRQ(ierr);
  for(k=0;k<nnsp_size;k++) { ierr = VecDestroy(&localnearnullsp[k]);CHKERRQ(ierr); }
  ierr = PetscFree(localnearnullsp);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}
#ifdef UNDEF_PETSC_MISSING_LAPACK_GESVD
#undef PETSC_MISSING_LAPACK_GESVD
#endif

/* -------------------------------------------------------------------------- */
/*
   PCBDDCCoarseSetUp -
*/
#undef __FUNCT__
#define __FUNCT__ "PCBDDCCoarseSetUp"
static PetscErrorCode PCBDDCCoarseSetUp(PC pc)
{
  PetscErrorCode  ierr;

  PC_IS*            pcis = (PC_IS*)(pc->data);
  PC_BDDC*          pcbddc = (PC_BDDC*)pc->data;
  Mat_IS            *matis = (Mat_IS*)pc->pmat->data;
  IS                is_R_local;
  IS                is_V_local;
  IS                is_C_local;
  IS                is_aux1;
  IS                is_aux2;
  const VecType     impVecType;
  const MatType     impMatType;
  PetscInt          n_R=0;
  PetscInt          n_D=0;
  PetscInt          n_B=0;
  PetscScalar       zero=0.0;
  PetscScalar       one=1.0;
  PetscScalar       m_one=-1.0;
  PetscScalar*      array;
  PetscScalar       *coarse_submat_vals;
  PetscInt          *idx_R_local;
  PetscInt          *idx_V_B;
  PetscScalar       *coarsefunctions_errors;
  PetscScalar       *constraints_errors;
  /* auxiliary indices */
  PetscInt s,i,j,k;
  /* for verbose output of bddc */
  PetscViewer       viewer=pcbddc->dbg_viewer;
  PetscBool         dbg_flag=pcbddc->dbg_flag;
  /* for counting coarse dofs */
  PetscScalar       coarsesum;
  PetscInt          n_vertices=pcbddc->n_vertices,n_constraints=pcbddc->n_constraints;
  PetscInt          size_of_constraint;
  PetscInt          *row_cmat_indices;
  PetscScalar       *row_cmat_values;
  const PetscInt    *vertices;

  PetscFunctionBegin;
  /* Set Non-overlapping dimensions */
  n_B = pcis->n_B; n_D = pcis->n - n_B;
  ierr = ISGetIndices(pcbddc->ISForVertices,&vertices);CHKERRQ(ierr);
  /* First let's count coarse dofs: note that we allow to have a constraint on a subdomain and not its counterpart on the neighbour subdomain (if user wants) */
  ierr = VecSet(pcis->vec1_N,zero);CHKERRQ(ierr);
  ierr = VecGetArray(pcis->vec1_N,&array);CHKERRQ(ierr);
  for(i=0;i<n_vertices;i++) { array[ vertices[i] ] = one; }

  for(i=0;i<n_constraints;i++) {
    ierr = MatGetRow(pcbddc->ConstraintMatrix,n_vertices+i,&size_of_constraint,(const PetscInt**)&row_cmat_indices,PETSC_NULL);CHKERRQ(ierr);
    for (j=0; j<size_of_constraint; j++) {
      k = row_cmat_indices[j];
      if( array[k] == zero ) {
        array[k] = one;
        break;
      }
    }
    ierr = MatRestoreRow(pcbddc->ConstraintMatrix,n_vertices+i,&size_of_constraint,(const PetscInt**)&row_cmat_indices,PETSC_NULL);CHKERRQ(ierr);
  }
  ierr = VecRestoreArray(pcis->vec1_N,&array);CHKERRQ(ierr);
  ierr = VecSet(pcis->vec1_global,zero);CHKERRQ(ierr);
  ierr = VecScatterBegin(matis->ctx,pcis->vec1_N,pcis->vec1_global,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
  ierr = VecScatterEnd  (matis->ctx,pcis->vec1_N,pcis->vec1_global,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
  ierr = VecScatterBegin(matis->ctx,pcis->vec1_global,pcis->vec1_N,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
  ierr = VecScatterEnd  (matis->ctx,pcis->vec1_global,pcis->vec1_N,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
  ierr = VecGetArray(pcis->vec1_N,&array);CHKERRQ(ierr);
  for(i=0;i<pcis->n;i++) { if( array[i] > zero) array[i] = one/array[i]; }
  ierr = VecRestoreArray(pcis->vec1_N,&array);CHKERRQ(ierr);
  ierr = VecSet(pcis->vec1_global,zero);CHKERRQ(ierr);
  ierr = VecScatterBegin(matis->ctx,pcis->vec1_N,pcis->vec1_global,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
  ierr = VecScatterEnd  (matis->ctx,pcis->vec1_N,pcis->vec1_global,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
  ierr = VecSum(pcis->vec1_global,&coarsesum);CHKERRQ(ierr);
  pcbddc->coarse_size = (PetscInt) coarsesum;

  /* Dohrmann's notation: dofs splitted in R (Remaining: all dofs but the vertices) and V (Vertices) */
  ierr = VecSet(pcis->vec1_N,one);CHKERRQ(ierr);
  ierr = VecGetArray(pcis->vec1_N,&array);CHKERRQ(ierr);
  for (i=0;i<n_vertices;i++) { array[ vertices[i] ] = zero; }
  ierr = PetscMalloc(( pcis->n - n_vertices )*sizeof(PetscInt),&idx_R_local);CHKERRQ(ierr);
  for (i=0, n_R=0; i<pcis->n; i++) { if (array[i] == one) { idx_R_local[n_R] = i; n_R++; } }
  ierr = VecRestoreArray(pcis->vec1_N,&array);CHKERRQ(ierr);
  if(dbg_flag) {
    ierr = PetscViewerASCIIPrintf(viewer,"--------------------------------------------------\n");CHKERRQ(ierr);
    ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
    ierr = PetscViewerASCIISynchronizedPrintf(viewer,"Subdomain %04d local dimensions\n",PetscGlobalRank);CHKERRQ(ierr);
    ierr = PetscViewerASCIISynchronizedPrintf(viewer,"local_size = %d, dirichlet_size = %d, boundary_size = %d\n",pcis->n,n_D,n_B);CHKERRQ(ierr);
    ierr = PetscViewerASCIISynchronizedPrintf(viewer,"r_size = %d, v_size = %d, constraints = %d, local_primal_size = %d\n",n_R,n_vertices,n_constraints,pcbddc->local_primal_size);CHKERRQ(ierr);
    ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
    ierr = PetscViewerASCIIPrintf(viewer,"--------------------------------------------------\n");CHKERRQ(ierr);
    ierr = PetscViewerASCIIPrintf(viewer,"Size of coarse problem = %d (%f)\n",pcbddc->coarse_size,coarsesum);CHKERRQ(ierr);
    ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
  }
  /* Allocate needed vectors */
  /* Set Mat type for local matrices needed by BDDC precondtioner */
  impMatType = MATSEQDENSE;
  impVecType = VECSEQ;
  ierr = VecDuplicate(pcis->vec1_D,&pcbddc->vec4_D);CHKERRQ(ierr);
  ierr = VecDuplicate(pcis->vec1_N,&pcis->vec2_N);CHKERRQ(ierr);
  ierr = VecCreate(PETSC_COMM_SELF,&pcbddc->vec1_R);CHKERRQ(ierr);
  ierr = VecSetSizes(pcbddc->vec1_R,n_R,n_R);CHKERRQ(ierr);
  ierr = VecSetType(pcbddc->vec1_R,impVecType);CHKERRQ(ierr);
  ierr = VecDuplicate(pcbddc->vec1_R,&pcbddc->vec2_R);CHKERRQ(ierr);
  ierr = VecCreate(PETSC_COMM_SELF,&pcbddc->vec1_P);CHKERRQ(ierr);
  ierr = VecSetSizes(pcbddc->vec1_P,pcbddc->local_primal_size,pcbddc->local_primal_size);CHKERRQ(ierr);
  ierr = VecSetType(pcbddc->vec1_P,impVecType);CHKERRQ(ierr);

  /* Creating some index sets needed  */
  /* For submatrices */
  ierr = ISCreateGeneral(PETSC_COMM_SELF,n_R,idx_R_local,PETSC_COPY_VALUES,&is_R_local);CHKERRQ(ierr);
  if(n_vertices)    {
    ierr = ISDuplicate(pcbddc->ISForVertices,&is_V_local);CHKERRQ(ierr);
    ierr = ISCopy(pcbddc->ISForVertices,is_V_local);CHKERRQ(ierr);
  }
  if(n_constraints) { ierr = ISCreateStride (PETSC_COMM_SELF,n_constraints,n_vertices,1,&is_C_local);CHKERRQ(ierr); }
  /* For VecScatters pcbddc->R_to_B and (optionally) pcbddc->R_to_D */
  {
    PetscInt   *aux_array1;
    PetscInt   *aux_array2;
    PetscScalar      value;

    ierr = PetscMalloc( (pcis->n_B-n_vertices)*sizeof(PetscInt),&aux_array1);CHKERRQ(ierr);
    ierr = PetscMalloc( (pcis->n_B-n_vertices)*sizeof(PetscInt),&aux_array2);CHKERRQ(ierr);

    ierr = VecSet(pcis->vec1_global,zero);CHKERRQ(ierr);
    ierr = VecScatterBegin(matis->ctx,pcis->vec1_N,pcis->vec1_global,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
    ierr = VecScatterEnd  (matis->ctx,pcis->vec1_N,pcis->vec1_global,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
    ierr = VecScatterBegin(matis->ctx,pcis->vec1_global,pcis->vec1_N,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
    ierr = VecScatterEnd  (matis->ctx,pcis->vec1_global,pcis->vec1_N,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
    ierr = VecScatterBegin(pcis->N_to_B,pcis->vec1_N,pcis->vec1_B,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
    ierr = VecScatterEnd  (pcis->N_to_B,pcis->vec1_N,pcis->vec1_B,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
    ierr = VecGetArray(pcis->vec1_N,&array);CHKERRQ(ierr);
    for (i=0, s=0; i<n_R; i++) { if (array[idx_R_local[i]] > one) { aux_array1[s] = i; s++; } }
    ierr = VecRestoreArray(pcis->vec1_N,&array);CHKERRQ(ierr);
    ierr = ISCreateGeneral(PETSC_COMM_SELF,s,aux_array1,PETSC_COPY_VALUES,&is_aux1);CHKERRQ(ierr);
    ierr = VecGetArray(pcis->vec1_B,&array);CHKERRQ(ierr);
    for (i=0, s=0; i<n_B; i++) { if (array[i] > one) { aux_array2[s] = i; s++; } }
    ierr = VecRestoreArray(pcis->vec1_B,&array);CHKERRQ(ierr);
    ierr = ISCreateGeneral(PETSC_COMM_SELF,s,aux_array2,PETSC_COPY_VALUES,&is_aux2);CHKERRQ(ierr);
    ierr = VecScatterCreate(pcbddc->vec1_R,is_aux1,pcis->vec1_B,is_aux2,&pcbddc->R_to_B);CHKERRQ(ierr);
    ierr = PetscFree(aux_array1);CHKERRQ(ierr);
    ierr = PetscFree(aux_array2);CHKERRQ(ierr);
    ierr = ISDestroy(&is_aux1);CHKERRQ(ierr);
    ierr = ISDestroy(&is_aux2);CHKERRQ(ierr);

    if(pcbddc->prec_type || dbg_flag ) {
      ierr = PetscMalloc(n_D*sizeof(PetscInt),&aux_array1);CHKERRQ(ierr);
      ierr = VecGetArray(pcis->vec1_N,&array);CHKERRQ(ierr);
      for (i=0, s=0; i<n_R; i++) { if (array[idx_R_local[i]] == one) { aux_array1[s] = i; s++; } }
      ierr = VecRestoreArray(pcis->vec1_N,&array);CHKERRQ(ierr);
      ierr = ISCreateGeneral(PETSC_COMM_SELF,s,aux_array1,PETSC_COPY_VALUES,&is_aux1);CHKERRQ(ierr);
      ierr = VecScatterCreate(pcbddc->vec1_R,is_aux1,pcis->vec1_D,(IS)0,&pcbddc->R_to_D);CHKERRQ(ierr);
      ierr = PetscFree(aux_array1);CHKERRQ(ierr);
      ierr = ISDestroy(&is_aux1);CHKERRQ(ierr);
    }

    /* Check scatters */
    if(dbg_flag) {

      Vec            vec_aux;

      ierr = PetscViewerASCIIPrintf(viewer,"--------------------------------------------------\n");CHKERRQ(ierr);
      ierr = PetscViewerASCIIPrintf(viewer,"Checking pcbddc->R_to_B scatter\n");CHKERRQ(ierr);
      ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
      ierr = VecSetRandom(pcbddc->vec1_R,PETSC_NULL);CHKERRQ(ierr);
      ierr = VecSetRandom(pcis->vec1_B,PETSC_NULL);CHKERRQ(ierr);
      ierr = VecDuplicate(pcbddc->vec1_R,&vec_aux);CHKERRQ(ierr);
      ierr = VecCopy(pcbddc->vec1_R,vec_aux);CHKERRQ(ierr);
      ierr = VecScatterBegin(pcbddc->R_to_B,pcbddc->vec1_R,pcis->vec1_B,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
      ierr = VecScatterEnd  (pcbddc->R_to_B,pcbddc->vec1_R,pcis->vec1_B,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
      ierr = VecScatterBegin(pcbddc->R_to_B,pcis->vec1_B,vec_aux,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
      ierr = VecScatterEnd  (pcbddc->R_to_B,pcis->vec1_B,vec_aux,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
      ierr = VecAXPY(vec_aux,m_one,pcbddc->vec1_R);CHKERRQ(ierr);
      ierr = VecNorm(vec_aux,NORM_INFINITY,&value);CHKERRQ(ierr);
      ierr = PetscViewerASCIISynchronizedPrintf(viewer,"Subdomain %04d R_to_B FORWARD error = % 1.14e\n",PetscGlobalRank,value);CHKERRQ(ierr);
      ierr = VecDestroy(&vec_aux);CHKERRQ(ierr);

      ierr = VecSetRandom(pcbddc->vec1_R,PETSC_NULL);CHKERRQ(ierr);
      ierr = VecSetRandom(pcis->vec1_B,PETSC_NULL);CHKERRQ(ierr);
      ierr = VecDuplicate(pcis->vec1_B,&vec_aux);CHKERRQ(ierr);
      ierr = VecCopy(pcis->vec1_B,vec_aux);CHKERRQ(ierr);
      ierr = VecScatterBegin(pcbddc->R_to_B,pcis->vec1_B,pcbddc->vec1_R,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
      ierr = VecScatterEnd  (pcbddc->R_to_B,pcis->vec1_B,pcbddc->vec1_R,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
      ierr = VecScatterBegin(pcbddc->R_to_B,pcbddc->vec1_R,vec_aux,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
      ierr = VecScatterEnd  (pcbddc->R_to_B,pcbddc->vec1_R,vec_aux,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
      ierr = VecAXPY(vec_aux,m_one,pcis->vec1_B);CHKERRQ(ierr);
      ierr = VecNorm(vec_aux,NORM_INFINITY,&value);CHKERRQ(ierr);
      ierr = PetscViewerASCIISynchronizedPrintf(viewer,"Subdomain %04d R_to_B REVERSE error = % 1.14e\n",PetscGlobalRank,value);CHKERRQ(ierr);
      ierr = VecDestroy(&vec_aux);CHKERRQ(ierr);

      ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
      ierr = PetscViewerASCIIPrintf(viewer,"Checking pcbddc->R_to_D scatter\n");CHKERRQ(ierr);
      ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);

      ierr = VecSetRandom(pcbddc->vec1_R,PETSC_NULL);CHKERRQ(ierr);
      ierr = VecSetRandom(pcis->vec1_D,PETSC_NULL);CHKERRQ(ierr);
      ierr = VecDuplicate(pcbddc->vec1_R,&vec_aux);CHKERRQ(ierr);
      ierr = VecCopy(pcbddc->vec1_R,vec_aux);CHKERRQ(ierr);
      ierr = VecScatterBegin(pcbddc->R_to_D,pcbddc->vec1_R,pcis->vec1_D,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
      ierr = VecScatterEnd  (pcbddc->R_to_D,pcbddc->vec1_R,pcis->vec1_D,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
      ierr = VecScatterBegin(pcbddc->R_to_D,pcis->vec1_D,vec_aux,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
      ierr = VecScatterEnd  (pcbddc->R_to_D,pcis->vec1_D,vec_aux,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
      ierr = VecAXPY(vec_aux,m_one,pcbddc->vec1_R);CHKERRQ(ierr);
      ierr = VecNorm(vec_aux,NORM_INFINITY,&value);CHKERRQ(ierr);
      ierr = PetscViewerASCIISynchronizedPrintf(viewer,"Subdomain %04d R_to_D FORWARD error = % 1.14e\n",PetscGlobalRank,value);CHKERRQ(ierr);
      ierr = VecDestroy(&vec_aux);CHKERRQ(ierr);

      ierr = VecSetRandom(pcbddc->vec1_R,PETSC_NULL);CHKERRQ(ierr);
      ierr = VecSetRandom(pcis->vec1_D,PETSC_NULL);CHKERRQ(ierr);
      ierr = VecDuplicate(pcis->vec1_D,&vec_aux);CHKERRQ(ierr);
      ierr = VecCopy(pcis->vec1_D,vec_aux);CHKERRQ(ierr);
      ierr = VecScatterBegin(pcbddc->R_to_D,pcis->vec1_D,pcbddc->vec1_R,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
      ierr = VecScatterEnd  (pcbddc->R_to_D,pcis->vec1_D,pcbddc->vec1_R,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
      ierr = VecScatterBegin(pcbddc->R_to_D,pcbddc->vec1_R,vec_aux,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
      ierr = VecScatterEnd  (pcbddc->R_to_D,pcbddc->vec1_R,vec_aux,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
      ierr = VecAXPY(vec_aux,m_one,pcis->vec1_D);CHKERRQ(ierr);
      ierr = VecNorm(vec_aux,NORM_INFINITY,&value);CHKERRQ(ierr);
      ierr = PetscViewerASCIISynchronizedPrintf(viewer,"Subdomain %04d R_to_D REVERSE error = % 1.14e\n",PetscGlobalRank,value);CHKERRQ(ierr);
      ierr = VecDestroy(&vec_aux);CHKERRQ(ierr);
      ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);

    }
  }

  /* vertices in boundary numbering */
  if(n_vertices) {
    ierr = VecSet(pcis->vec1_N,m_one);CHKERRQ(ierr);
    ierr = VecGetArray(pcis->vec1_N,&array);CHKERRQ(ierr);
    for (i=0; i<n_vertices; i++) { array[ vertices[i] ] = i; }
    ierr = VecRestoreArray(pcis->vec1_N,&array);CHKERRQ(ierr);
    ierr = VecScatterBegin(pcis->N_to_B,pcis->vec1_N,pcis->vec1_B,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
    ierr = VecScatterEnd  (pcis->N_to_B,pcis->vec1_N,pcis->vec1_B,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
    ierr = PetscMalloc(n_vertices*sizeof(PetscInt),&idx_V_B);CHKERRQ(ierr);
    ierr = VecGetArray(pcis->vec1_B,&array);CHKERRQ(ierr);
    for (i=0; i<n_vertices; i++) {
      s=0;
      while (array[s] != i ) {s++;}
      idx_V_B[i]=s;
    }
    ierr = VecRestoreArray(pcis->vec1_B,&array);CHKERRQ(ierr);
  }


  /* Creating PC contexts for local Dirichlet and Neumann problems */
  {
    Mat  A_RR;
    PC   pc_temp;
    /* Matrix for Dirichlet problem is A_II -> we already have it from pcis.c code */
    ierr = KSPCreate(PETSC_COMM_SELF,&pcbddc->ksp_D);CHKERRQ(ierr);
    ierr = PetscObjectIncrementTabLevel((PetscObject)pcbddc->ksp_D,(PetscObject)pc,1);CHKERRQ(ierr);
    ierr = KSPSetOperators(pcbddc->ksp_D,pcis->A_II,pcis->A_II,SAME_PRECONDITIONER);CHKERRQ(ierr);
    ierr = KSPSetType(pcbddc->ksp_D,KSPPREONLY);CHKERRQ(ierr);
    //ierr = KSPSetOptionsPrefix();CHKERRQ(ierr);
    /* default */
    ierr = KSPGetPC(pcbddc->ksp_D,&pc_temp);CHKERRQ(ierr);
    ierr = PCSetType(pc_temp,PCLU);CHKERRQ(ierr);
    /* Allow user's customization */
    ierr = KSPSetFromOptions(pcbddc->ksp_D);CHKERRQ(ierr);
    /* Set Up KSP for Dirichlet problem of BDDC */
    ierr = KSPSetUp(pcbddc->ksp_D);CHKERRQ(ierr);
    /* Matrix for Neumann problem is A_RR -> we need to create it */
    ierr = MatGetSubMatrix(matis->A,is_R_local,is_R_local,MAT_INITIAL_MATRIX,&A_RR);CHKERRQ(ierr);
    ierr = KSPCreate(PETSC_COMM_SELF,&pcbddc->ksp_R);CHKERRQ(ierr);
    ierr = PetscObjectIncrementTabLevel((PetscObject)pcbddc->ksp_R,(PetscObject)pc,1);CHKERRQ(ierr);
    ierr = KSPSetOperators(pcbddc->ksp_R,A_RR,A_RR,SAME_PRECONDITIONER);CHKERRQ(ierr);
    ierr = KSPSetType(pcbddc->ksp_R,KSPPREONLY);CHKERRQ(ierr);
    //ierr = KSPSetOptionsPrefix();CHKERRQ(ierr);
    /* default */
    ierr = KSPGetPC(pcbddc->ksp_R,&pc_temp);CHKERRQ(ierr);
    ierr = PCSetType(pc_temp,PCLU);CHKERRQ(ierr);
    /* Allow user's customization */
    ierr = KSPSetFromOptions(pcbddc->ksp_R);CHKERRQ(ierr);
    /* Set Up KSP for Neumann problem of BDDC */
    ierr = KSPSetUp(pcbddc->ksp_R);CHKERRQ(ierr);
    /* check Dirichlet and Neumann solvers */
    if(pcbddc->dbg_flag) {
      Vec temp_vec;
      PetscScalar value;

      ierr = VecDuplicate(pcis->vec1_D,&temp_vec);CHKERRQ(ierr);
      ierr = VecSetRandom(pcis->vec1_D,PETSC_NULL);CHKERRQ(ierr);
      ierr = MatMult(pcis->A_II,pcis->vec1_D,pcis->vec2_D);CHKERRQ(ierr);
      ierr = KSPSolve(pcbddc->ksp_D,pcis->vec2_D,temp_vec);CHKERRQ(ierr);
      ierr = VecAXPY(temp_vec,m_one,pcis->vec1_D);CHKERRQ(ierr);
      ierr = VecNorm(temp_vec,NORM_INFINITY,&value);CHKERRQ(ierr);
      ierr = VecDestroy(&temp_vec);CHKERRQ(ierr);
      ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
      ierr = PetscViewerASCIIPrintf(viewer,"--------------------------------------------------\n");CHKERRQ(ierr);
      ierr = PetscViewerASCIIPrintf(viewer,"Checking solution of Dirichlet and Neumann problems\n");CHKERRQ(ierr);
      ierr = PetscViewerASCIISynchronizedPrintf(viewer,"Subdomain %04d infinity error for Dirichlet solve = % 1.14e \n",PetscGlobalRank,value);CHKERRQ(ierr);
      ierr = VecDuplicate(pcbddc->vec1_R,&temp_vec);CHKERRQ(ierr);
      ierr = VecSetRandom(pcbddc->vec1_R,PETSC_NULL);CHKERRQ(ierr);
      ierr = MatMult(A_RR,pcbddc->vec1_R,pcbddc->vec2_R);CHKERRQ(ierr);
      ierr = KSPSolve(pcbddc->ksp_R,pcbddc->vec2_R,temp_vec);CHKERRQ(ierr);
      ierr = VecAXPY(temp_vec,m_one,pcbddc->vec1_R);CHKERRQ(ierr);
      ierr = VecNorm(temp_vec,NORM_INFINITY,&value);CHKERRQ(ierr);
      ierr = VecDestroy(&temp_vec);CHKERRQ(ierr);
      ierr = PetscViewerASCIISynchronizedPrintf(viewer,"Subdomain %04d infinity error for  Neumann  solve = % 1.14e \n",PetscGlobalRank,value);CHKERRQ(ierr);
      ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
    }
    /* free Neumann problem's matrix */
    ierr = MatDestroy(&A_RR);CHKERRQ(ierr);
  }

  /* Assemble all remaining stuff needed to apply BDDC  */
  {
    Mat          A_RV,A_VR,A_VV;
    Mat          M1,M2;
    Mat          C_CR;
    Mat          AUXMAT;
    Vec          vec1_C;
    Vec          vec2_C;
    Vec          vec1_V;
    Vec          vec2_V;
    PetscInt     *nnz;
    PetscInt     *auxindices;
    PetscInt     index;
    PetscScalar* array2;
    MatFactorInfo matinfo;

    /* Allocating some extra storage just to be safe */
    ierr = PetscMalloc (pcis->n*sizeof(PetscInt),&nnz);CHKERRQ(ierr);
    ierr = PetscMalloc (pcis->n*sizeof(PetscInt),&auxindices);CHKERRQ(ierr);
    for(i=0;i<pcis->n;i++) {auxindices[i]=i;}

    /* some work vectors on vertices and/or constraints */
    if(n_vertices) {
      ierr = VecCreate(PETSC_COMM_SELF,&vec1_V);CHKERRQ(ierr);
      ierr = VecSetSizes(vec1_V,n_vertices,n_vertices);CHKERRQ(ierr);
      ierr = VecSetType(vec1_V,impVecType);CHKERRQ(ierr);
      ierr = VecDuplicate(vec1_V,&vec2_V);CHKERRQ(ierr);
    }
    if(pcbddc->n_constraints) {
      ierr = VecCreate(PETSC_COMM_SELF,&vec1_C);CHKERRQ(ierr);
      ierr = VecSetSizes(vec1_C,pcbddc->n_constraints,pcbddc->n_constraints);CHKERRQ(ierr);
      ierr = VecSetType(vec1_C,impVecType);CHKERRQ(ierr);
      ierr = VecDuplicate(vec1_C,&vec2_C);CHKERRQ(ierr);
      ierr = VecDuplicate(vec1_C,&pcbddc->vec1_C);CHKERRQ(ierr);
    }
    /* Precompute stuffs needed for preprocessing and application of BDDC*/
    if(n_constraints) {
      /* some work vectors */
      ierr = MatCreate(PETSC_COMM_SELF,&pcbddc->local_auxmat2);CHKERRQ(ierr);
      ierr = MatSetSizes(pcbddc->local_auxmat2,n_R,n_constraints,n_R,n_constraints);CHKERRQ(ierr);
      ierr = MatSetType(pcbddc->local_auxmat2,impMatType);CHKERRQ(ierr);
      ierr = MatSeqDenseSetPreallocation(pcbddc->local_auxmat2,PETSC_NULL);CHKERRQ(ierr);

      /* Assemble local_auxmat2 = - A_{RR}^{-1} C^T_{CR} needed by BDDC application */
      for(i=0;i<n_constraints;i++) {
        ierr = VecSet(pcis->vec1_N,zero);CHKERRQ(ierr);
        ierr = VecSet(pcbddc->vec1_R,zero);CHKERRQ(ierr);
        /* Get row of constraint matrix in R numbering */
        ierr = VecGetArray(pcis->vec1_N,&array);CHKERRQ(ierr);
        ierr = MatGetRow(pcbddc->ConstraintMatrix,n_vertices+i,&size_of_constraint,(const PetscInt**)&row_cmat_indices,(const PetscScalar**)&row_cmat_values);CHKERRQ(ierr);
        for(j=0;j<size_of_constraint;j++) { array[ row_cmat_indices[j] ] = - row_cmat_values[j]; }
        ierr = MatRestoreRow(pcbddc->ConstraintMatrix,n_vertices+i,&size_of_constraint,(const PetscInt**)&row_cmat_indices,(const PetscScalar**)&row_cmat_values);CHKERRQ(ierr);
        ierr = VecGetArray(pcbddc->vec1_R,&array2);CHKERRQ(ierr);
        for(j=0;j<n_R;j++) { array2[j] = array[ idx_R_local[j] ]; }
        ierr = VecRestoreArray(pcis->vec1_N,&array);CHKERRQ(ierr);
        ierr = VecRestoreArray(pcbddc->vec1_R,&array2);CHKERRQ(ierr);
        /* Solve for row of constraint matrix in R numbering */
        ierr = KSPSolve(pcbddc->ksp_R,pcbddc->vec1_R,pcbddc->vec2_R);CHKERRQ(ierr);
        /* Set values */
        ierr = VecGetArray(pcbddc->vec2_R,&array);CHKERRQ(ierr);
        ierr = MatSetValues(pcbddc->local_auxmat2,n_R,auxindices,1,&i,array,INSERT_VALUES);CHKERRQ(ierr);
        ierr = VecRestoreArray(pcbddc->vec2_R,&array);CHKERRQ(ierr);
      }
      ierr = MatAssemblyBegin(pcbddc->local_auxmat2,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
      ierr = MatAssemblyEnd(pcbddc->local_auxmat2,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);

      /* Create Constraint matrix on R nodes: C_{CR}  */
      ierr = MatGetSubMatrix(pcbddc->ConstraintMatrix,is_C_local,is_R_local,MAT_INITIAL_MATRIX,&C_CR);CHKERRQ(ierr);
      ierr = ISDestroy(&is_C_local);CHKERRQ(ierr);

      /* Assemble AUXMAT = ( LUFactor )( -C_{CR} A_{RR}^{-1} C^T_{CR} )^{-1} */
      ierr = MatMatMult(C_CR,pcbddc->local_auxmat2,MAT_INITIAL_MATRIX,PETSC_DEFAULT,&AUXMAT);CHKERRQ(ierr);
      ierr = MatFactorInfoInitialize(&matinfo);CHKERRQ(ierr);
      ierr = ISCreateStride(PETSC_COMM_SELF,n_constraints,0,1,&is_aux1);CHKERRQ(ierr);
      ierr = MatLUFactor(AUXMAT,is_aux1,is_aux1,&matinfo);CHKERRQ(ierr);
      ierr = ISDestroy(&is_aux1);CHKERRQ(ierr);

      /* Assemble explicitly M1 = ( C_{CR} A_{RR}^{-1} C^T_{CR} )^{-1} needed in preproc  */
      ierr = MatCreate(PETSC_COMM_SELF,&M1);CHKERRQ(ierr);
      ierr = MatSetSizes(M1,n_constraints,n_constraints,n_constraints,n_constraints);CHKERRQ(ierr);
      ierr = MatSetType(M1,impMatType);CHKERRQ(ierr);
      ierr = MatSeqDenseSetPreallocation(M1,PETSC_NULL);CHKERRQ(ierr);
      for(i=0;i<n_constraints;i++) {
        ierr = VecSet(vec1_C,zero);CHKERRQ(ierr);
        ierr = VecSetValue(vec1_C,i,one,INSERT_VALUES);CHKERRQ(ierr);
        ierr = VecAssemblyBegin(vec1_C);CHKERRQ(ierr);
        ierr = VecAssemblyEnd(vec1_C);CHKERRQ(ierr);
        ierr = MatSolve(AUXMAT,vec1_C,vec2_C);CHKERRQ(ierr);
        ierr = VecScale(vec2_C,m_one);CHKERRQ(ierr);
        ierr = VecGetArray(vec2_C,&array);CHKERRQ(ierr);
        ierr = MatSetValues(M1,n_constraints,auxindices,1,&i,array,INSERT_VALUES);CHKERRQ(ierr);
        ierr = VecRestoreArray(vec2_C,&array);CHKERRQ(ierr);
      }
      ierr = MatAssemblyBegin(M1,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
      ierr = MatAssemblyEnd(M1,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
      ierr = MatDestroy(&AUXMAT);CHKERRQ(ierr);
      /* Assemble local_auxmat1 = M1*C_{CR} needed by BDDC application in KSP and in preproc */
      ierr = MatMatMult(M1,C_CR,MAT_INITIAL_MATRIX,PETSC_DEFAULT,&pcbddc->local_auxmat1);CHKERRQ(ierr);

    }

    /* Get submatrices from subdomain matrix */
    if(n_vertices){
      ierr = MatGetSubMatrix(matis->A,is_R_local,is_V_local,MAT_INITIAL_MATRIX,&A_RV);CHKERRQ(ierr);
      ierr = MatGetSubMatrix(matis->A,is_V_local,is_R_local,MAT_INITIAL_MATRIX,&A_VR);CHKERRQ(ierr);
      ierr = MatGetSubMatrix(matis->A,is_V_local,is_V_local,MAT_INITIAL_MATRIX,&A_VV);CHKERRQ(ierr);
      /* Assemble M2 = A_RR^{-1}A_RV */
      ierr = MatCreate(PETSC_COMM_SELF,&M2);CHKERRQ(ierr);
      ierr = MatSetSizes(M2,n_R,n_vertices,n_R,n_vertices);CHKERRQ(ierr);
      ierr = MatSetType(M2,impMatType);CHKERRQ(ierr);
      ierr = MatSeqDenseSetPreallocation(M2,PETSC_NULL);CHKERRQ(ierr);
      for(i=0;i<n_vertices;i++) {
        ierr = VecSet(vec1_V,zero);CHKERRQ(ierr);
        ierr = VecSetValue(vec1_V,i,one,INSERT_VALUES);CHKERRQ(ierr);
        ierr = VecAssemblyBegin(vec1_V);CHKERRQ(ierr);
        ierr = VecAssemblyEnd(vec1_V);CHKERRQ(ierr);
        ierr = MatMult(A_RV,vec1_V,pcbddc->vec1_R);CHKERRQ(ierr);
        ierr = KSPSolve(pcbddc->ksp_R,pcbddc->vec1_R,pcbddc->vec2_R);CHKERRQ(ierr);
        ierr = VecGetArray(pcbddc->vec2_R,&array);CHKERRQ(ierr);
        ierr = MatSetValues(M2,n_R,auxindices,1,&i,array,INSERT_VALUES);CHKERRQ(ierr);
        ierr = VecRestoreArray(pcbddc->vec2_R,&array);CHKERRQ(ierr);
      }
      ierr = MatAssemblyBegin(M2,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
      ierr = MatAssemblyEnd(M2,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
    }

    /* Matrix of coarse basis functions (local) */
    ierr = MatCreate(PETSC_COMM_SELF,&pcbddc->coarse_phi_B);CHKERRQ(ierr);
    ierr = MatSetSizes(pcbddc->coarse_phi_B,n_B,pcbddc->local_primal_size,n_B,pcbddc->local_primal_size);CHKERRQ(ierr);
    ierr = MatSetType(pcbddc->coarse_phi_B,impMatType);CHKERRQ(ierr);
    ierr = MatSeqDenseSetPreallocation(pcbddc->coarse_phi_B,PETSC_NULL);CHKERRQ(ierr);
    if(pcbddc->prec_type || dbg_flag ) {
      ierr = MatCreate(PETSC_COMM_SELF,&pcbddc->coarse_phi_D);CHKERRQ(ierr);
      ierr = MatSetSizes(pcbddc->coarse_phi_D,n_D,pcbddc->local_primal_size,n_D,pcbddc->local_primal_size);CHKERRQ(ierr);
      ierr = MatSetType(pcbddc->coarse_phi_D,impMatType);CHKERRQ(ierr);
      ierr = MatSeqDenseSetPreallocation(pcbddc->coarse_phi_D,PETSC_NULL);CHKERRQ(ierr);
    }

    if(dbg_flag) {
      ierr = PetscMalloc( pcbddc->local_primal_size*sizeof(PetscScalar),&coarsefunctions_errors);CHKERRQ(ierr);
      ierr = PetscMalloc( pcbddc->local_primal_size*sizeof(PetscScalar),&constraints_errors);CHKERRQ(ierr);
    }
    /* Subdomain contribution (Non-overlapping) to coarse matrix  */
    ierr = PetscMalloc ((pcbddc->local_primal_size)*(pcbddc->local_primal_size)*sizeof(PetscScalar),&coarse_submat_vals);CHKERRQ(ierr);

    /* We are now ready to evaluate coarse basis functions and subdomain contribution to coarse problem */
    for(i=0;i<n_vertices;i++){
      ierr = VecSet(vec1_V,zero);CHKERRQ(ierr);
      ierr = VecSetValue(vec1_V,i,one,INSERT_VALUES);CHKERRQ(ierr);
      ierr = VecAssemblyBegin(vec1_V);CHKERRQ(ierr);
      ierr = VecAssemblyEnd(vec1_V);CHKERRQ(ierr);
      /* solution of saddle point problem */
      ierr = MatMult(M2,vec1_V,pcbddc->vec1_R);CHKERRQ(ierr);
      ierr = VecScale(pcbddc->vec1_R,m_one);CHKERRQ(ierr);
      if(n_constraints) {
        ierr = MatMult(pcbddc->local_auxmat1,pcbddc->vec1_R,vec1_C);CHKERRQ(ierr);
        ierr = MatMultAdd(pcbddc->local_auxmat2,vec1_C,pcbddc->vec1_R,pcbddc->vec1_R);CHKERRQ(ierr);
        ierr = VecScale(vec1_C,m_one);CHKERRQ(ierr);
      }
      ierr = MatMult(A_VR,pcbddc->vec1_R,vec2_V);CHKERRQ(ierr);
      ierr = MatMultAdd(A_VV,vec1_V,vec2_V,vec2_V);CHKERRQ(ierr);

      /* Set values in coarse basis function and subdomain part of coarse_mat */
      /* coarse basis functions */
      ierr = VecSet(pcis->vec1_B,zero);CHKERRQ(ierr);
      ierr = VecScatterBegin(pcbddc->R_to_B,pcbddc->vec1_R,pcis->vec1_B,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
      ierr = VecScatterEnd  (pcbddc->R_to_B,pcbddc->vec1_R,pcis->vec1_B,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
      ierr = VecGetArray(pcis->vec1_B,&array);CHKERRQ(ierr);
      ierr = MatSetValues(pcbddc->coarse_phi_B,n_B,auxindices,1,&i,array,INSERT_VALUES);CHKERRQ(ierr);
      ierr = VecRestoreArray(pcis->vec1_B,&array);CHKERRQ(ierr);
      ierr = MatSetValue(pcbddc->coarse_phi_B,idx_V_B[i],i,one,INSERT_VALUES);CHKERRQ(ierr);
      if( pcbddc->prec_type || dbg_flag  ) {
        ierr = VecScatterBegin(pcbddc->R_to_D,pcbddc->vec1_R,pcis->vec1_D,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
        ierr = VecScatterEnd(pcbddc->R_to_D,pcbddc->vec1_R,pcis->vec1_D,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
        ierr = VecGetArray(pcis->vec1_D,&array);CHKERRQ(ierr);
        ierr = MatSetValues(pcbddc->coarse_phi_D,n_D,auxindices,1,&i,array,INSERT_VALUES);CHKERRQ(ierr);
        ierr = VecRestoreArray(pcis->vec1_D,&array);CHKERRQ(ierr);
      }
      /* subdomain contribution to coarse matrix */
      ierr = VecGetArray(vec2_V,&array);CHKERRQ(ierr);
      for(j=0;j<n_vertices;j++) { coarse_submat_vals[i*pcbddc->local_primal_size+j] = array[j]; } //WARNING -> column major ordering
      ierr = VecRestoreArray(vec2_V,&array);CHKERRQ(ierr);
      if(n_constraints) {
        ierr = VecGetArray(vec1_C,&array);CHKERRQ(ierr);
        for(j=0;j<n_constraints;j++) { coarse_submat_vals[i*pcbddc->local_primal_size+j+n_vertices] = array[j]; } //WARNING -> column major ordering
        ierr = VecRestoreArray(vec1_C,&array);CHKERRQ(ierr);
      }

      if( dbg_flag ) {
        /* assemble subdomain vector on nodes */
        ierr = VecSet(pcis->vec1_N,zero);CHKERRQ(ierr);
        ierr = VecGetArray(pcis->vec1_N,&array);CHKERRQ(ierr);
        ierr = VecGetArray(pcbddc->vec1_R,&array2);CHKERRQ(ierr);
        for(j=0;j<n_R;j++) { array[idx_R_local[j]] = array2[j]; }
        array[ vertices[i] ] = one;
        ierr = VecRestoreArray(pcbddc->vec1_R,&array2);CHKERRQ(ierr);
        ierr = VecRestoreArray(pcis->vec1_N,&array);CHKERRQ(ierr);
        /* assemble subdomain vector of lagrange multipliers (i.e. primal nodes) */
        ierr = VecSet(pcbddc->vec1_P,zero);CHKERRQ(ierr);
        ierr = VecGetArray(pcbddc->vec1_P,&array2);CHKERRQ(ierr);
        ierr = VecGetArray(vec2_V,&array);CHKERRQ(ierr);
        for(j=0;j<n_vertices;j++) { array2[j]=array[j]; }
        ierr = VecRestoreArray(vec2_V,&array);CHKERRQ(ierr);
        if(n_constraints) {
          ierr = VecGetArray(vec1_C,&array);CHKERRQ(ierr);
          for(j=0;j<n_constraints;j++) { array2[j+n_vertices]=array[j]; }
          ierr = VecRestoreArray(vec1_C,&array);CHKERRQ(ierr);
        }
        ierr = VecRestoreArray(pcbddc->vec1_P,&array2);CHKERRQ(ierr);
        ierr = VecScale(pcbddc->vec1_P,m_one);CHKERRQ(ierr);
        /* check saddle point solution */
        ierr = MatMult(matis->A,pcis->vec1_N,pcis->vec2_N);CHKERRQ(ierr);
        ierr = MatMultTransposeAdd(pcbddc->ConstraintMatrix,pcbddc->vec1_P,pcis->vec2_N,pcis->vec2_N);CHKERRQ(ierr);
        ierr = VecNorm(pcis->vec2_N,NORM_INFINITY,&coarsefunctions_errors[i]);CHKERRQ(ierr);
        ierr = MatMult(pcbddc->ConstraintMatrix,pcis->vec1_N,pcbddc->vec1_P);CHKERRQ(ierr);
        ierr = VecGetArray(pcbddc->vec1_P,&array);CHKERRQ(ierr);
        array[i]=array[i]+m_one;  /* shift by the identity matrix */
        ierr = VecRestoreArray(pcbddc->vec1_P,&array);CHKERRQ(ierr);
        ierr = VecNorm(pcbddc->vec1_P,NORM_INFINITY,&constraints_errors[i]);CHKERRQ(ierr);
      }
    }

    for(i=0;i<n_constraints;i++){
      ierr = VecSet(vec2_C,zero);CHKERRQ(ierr);
      ierr = VecSetValue(vec2_C,i,m_one,INSERT_VALUES);CHKERRQ(ierr);
      ierr = VecAssemblyBegin(vec2_C);CHKERRQ(ierr);
      ierr = VecAssemblyEnd(vec2_C);CHKERRQ(ierr);
      /* solution of saddle point problem */
      ierr = MatMult(M1,vec2_C,vec1_C);CHKERRQ(ierr);
      ierr = MatMult(pcbddc->local_auxmat2,vec1_C,pcbddc->vec1_R);CHKERRQ(ierr);
      ierr = VecScale(vec1_C,m_one);CHKERRQ(ierr);
      if(n_vertices) { ierr = MatMult(A_VR,pcbddc->vec1_R,vec2_V);CHKERRQ(ierr); }
      /* Set values in coarse basis function and subdomain part of coarse_mat */
      /* coarse basis functions */
      index=i+n_vertices;
      ierr = VecSet(pcis->vec1_B,zero);CHKERRQ(ierr);
      ierr = VecScatterBegin(pcbddc->R_to_B,pcbddc->vec1_R,pcis->vec1_B,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
      ierr = VecScatterEnd  (pcbddc->R_to_B,pcbddc->vec1_R,pcis->vec1_B,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
      ierr = VecGetArray(pcis->vec1_B,&array);CHKERRQ(ierr);
      ierr = MatSetValues(pcbddc->coarse_phi_B,n_B,auxindices,1,&index,array,INSERT_VALUES);CHKERRQ(ierr);
      ierr = VecRestoreArray(pcis->vec1_B,&array);CHKERRQ(ierr);
      if( pcbddc->prec_type || dbg_flag ) {
        ierr = VecScatterBegin(pcbddc->R_to_D,pcbddc->vec1_R,pcis->vec1_D,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
        ierr = VecScatterEnd(pcbddc->R_to_D,pcbddc->vec1_R,pcis->vec1_D,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
        ierr = VecGetArray(pcis->vec1_D,&array);CHKERRQ(ierr);
        ierr = MatSetValues(pcbddc->coarse_phi_D,n_D,auxindices,1,&index,array,INSERT_VALUES);CHKERRQ(ierr);
        ierr = VecRestoreArray(pcis->vec1_D,&array);CHKERRQ(ierr);
      }
      /* subdomain contribution to coarse matrix */
      if(n_vertices) {
        ierr = VecGetArray(vec2_V,&array);CHKERRQ(ierr);
        for(j=0;j<n_vertices;j++) {coarse_submat_vals[index*pcbddc->local_primal_size+j]=array[j];} //WARNING -> column major ordering
        ierr = VecRestoreArray(vec2_V,&array);CHKERRQ(ierr);
      }
      ierr = VecGetArray(vec1_C,&array);CHKERRQ(ierr);
      for(j=0;j<n_constraints;j++) {coarse_submat_vals[index*pcbddc->local_primal_size+j+n_vertices]=array[j];} //WARNING -> column major ordering
      ierr = VecRestoreArray(vec1_C,&array);CHKERRQ(ierr);

      if( dbg_flag ) {
        /* assemble subdomain vector on nodes */
        ierr = VecSet(pcis->vec1_N,zero);CHKERRQ(ierr);
        ierr = VecGetArray(pcis->vec1_N,&array);CHKERRQ(ierr);
        ierr = VecGetArray(pcbddc->vec1_R,&array2);CHKERRQ(ierr);
        for(j=0;j<n_R;j++){ array[ idx_R_local[j] ] = array2[j]; }
        ierr = VecRestoreArray(pcbddc->vec1_R,&array2);CHKERRQ(ierr);
        ierr = VecRestoreArray(pcis->vec1_N,&array);CHKERRQ(ierr);
        /* assemble subdomain vector of lagrange multipliers */
        ierr = VecSet(pcbddc->vec1_P,zero);CHKERRQ(ierr);
        ierr = VecGetArray(pcbddc->vec1_P,&array2);CHKERRQ(ierr);
        if( n_vertices) {
          ierr = VecGetArray(vec2_V,&array);CHKERRQ(ierr);
          for(j=0;j<n_vertices;j++) {array2[j]=-array[j];}
          ierr = VecRestoreArray(vec2_V,&array);CHKERRQ(ierr);
        }
        ierr = VecGetArray(vec1_C,&array);CHKERRQ(ierr);
        for(j=0;j<n_constraints;j++) {array2[j+n_vertices]=-array[j];}
        ierr = VecRestoreArray(vec1_C,&array);CHKERRQ(ierr);
        ierr = VecRestoreArray(pcbddc->vec1_P,&array2);CHKERRQ(ierr);
        /* check saddle point solution */
        ierr = MatMult(matis->A,pcis->vec1_N,pcis->vec2_N);CHKERRQ(ierr);
        ierr = MatMultTransposeAdd(pcbddc->ConstraintMatrix,pcbddc->vec1_P,pcis->vec2_N,pcis->vec2_N);CHKERRQ(ierr);
        ierr = VecNorm(pcis->vec2_N,NORM_INFINITY,&coarsefunctions_errors[index]);CHKERRQ(ierr);
        ierr = MatMult(pcbddc->ConstraintMatrix,pcis->vec1_N,pcbddc->vec1_P);CHKERRQ(ierr);
        ierr = VecGetArray(pcbddc->vec1_P,&array);CHKERRQ(ierr);
        array[index]=array[index]+m_one; /* shift by the identity matrix */
        ierr = VecRestoreArray(pcbddc->vec1_P,&array);CHKERRQ(ierr);
        ierr = VecNorm(pcbddc->vec1_P,NORM_INFINITY,&constraints_errors[index]);CHKERRQ(ierr);
      }
    }
    ierr = MatAssemblyBegin(pcbddc->coarse_phi_B,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
    ierr = MatAssemblyEnd  (pcbddc->coarse_phi_B,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
    if( pcbddc->prec_type || dbg_flag ) {
      ierr = MatAssemblyBegin(pcbddc->coarse_phi_D,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
      ierr = MatAssemblyEnd  (pcbddc->coarse_phi_D,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
    }
    /* Checking coarse_sub_mat and coarse basis functios */
    /* It shuld be \Phi^{(j)^T} A^{(j)} \Phi^{(j)}=coarse_sub_mat */
    if(dbg_flag) {

      Mat coarse_sub_mat;
      Mat TM1,TM2,TM3,TM4;
      Mat coarse_phi_D,coarse_phi_B,A_II,A_BB,A_IB,A_BI;
      const MatType checkmattype=MATSEQAIJ;
      PetscScalar      value;

      ierr = MatConvert(pcis->A_II,checkmattype,MAT_INITIAL_MATRIX,&A_II);CHKERRQ(ierr);
      ierr = MatConvert(pcis->A_IB,checkmattype,MAT_INITIAL_MATRIX,&A_IB);CHKERRQ(ierr);
      ierr = MatConvert(pcis->A_BI,checkmattype,MAT_INITIAL_MATRIX,&A_BI);CHKERRQ(ierr);
      ierr = MatConvert(pcis->A_BB,checkmattype,MAT_INITIAL_MATRIX,&A_BB);CHKERRQ(ierr);
      ierr = MatConvert(pcbddc->coarse_phi_D,checkmattype,MAT_INITIAL_MATRIX,&coarse_phi_D);CHKERRQ(ierr);
      ierr = MatConvert(pcbddc->coarse_phi_B,checkmattype,MAT_INITIAL_MATRIX,&coarse_phi_B);CHKERRQ(ierr);
      ierr = MatCreateSeqDense(PETSC_COMM_SELF,pcbddc->local_primal_size,pcbddc->local_primal_size,coarse_submat_vals,&coarse_sub_mat);CHKERRQ(ierr);
      ierr = MatConvert(coarse_sub_mat,checkmattype,MAT_REUSE_MATRIX,&coarse_sub_mat);CHKERRQ(ierr);

      ierr = PetscViewerASCIIPrintf(viewer,"--------------------------------------------------\n");CHKERRQ(ierr);
      ierr = PetscViewerASCIIPrintf(viewer,"Check coarse sub mat and local basis functions\n");CHKERRQ(ierr);
      ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
      ierr = MatPtAP(A_II,coarse_phi_D,MAT_INITIAL_MATRIX,1.0,&TM1);CHKERRQ(ierr);
      ierr = MatPtAP(A_BB,coarse_phi_B,MAT_INITIAL_MATRIX,1.0,&TM2);CHKERRQ(ierr);
      ierr = MatMatMult(A_IB,coarse_phi_B,MAT_INITIAL_MATRIX,1.0,&AUXMAT);CHKERRQ(ierr);
      ierr = MatTransposeMatMult(coarse_phi_D,AUXMAT,MAT_INITIAL_MATRIX,1.0,&TM3);CHKERRQ(ierr);
      ierr = MatDestroy(&AUXMAT);CHKERRQ(ierr);
      ierr = MatMatMult(A_BI,coarse_phi_D,MAT_INITIAL_MATRIX,1.0,&AUXMAT);CHKERRQ(ierr);
      ierr = MatTransposeMatMult(coarse_phi_B,AUXMAT,MAT_INITIAL_MATRIX,1.0,&TM4);CHKERRQ(ierr);
      ierr = MatDestroy(&AUXMAT);CHKERRQ(ierr);
      ierr = MatAXPY(TM1,one,TM2,DIFFERENT_NONZERO_PATTERN);CHKERRQ(ierr);
      ierr = MatAXPY(TM1,one,TM3,DIFFERENT_NONZERO_PATTERN);CHKERRQ(ierr);
      ierr = MatAXPY(TM1,one,TM4,DIFFERENT_NONZERO_PATTERN);CHKERRQ(ierr);
      ierr = MatAXPY(TM1,m_one,coarse_sub_mat,DIFFERENT_NONZERO_PATTERN);CHKERRQ(ierr);
      ierr = MatNorm(TM1,NORM_INFINITY,&value);CHKERRQ(ierr);
      ierr = PetscViewerASCIISynchronizedPrintf(viewer,"----------------------------------\n");CHKERRQ(ierr);
      ierr = PetscViewerASCIISynchronizedPrintf(viewer,"Subdomain %04d \n",PetscGlobalRank);CHKERRQ(ierr);
      ierr = PetscViewerASCIISynchronizedPrintf(viewer,"matrix error = % 1.14e\n",value);CHKERRQ(ierr);
      ierr = PetscViewerASCIISynchronizedPrintf(viewer,"coarse functions errors\n");CHKERRQ(ierr);
      for(i=0;i<pcbddc->local_primal_size;i++) { ierr = PetscViewerASCIISynchronizedPrintf(viewer,"local %02d-th function error = % 1.14e\n",i,coarsefunctions_errors[i]);CHKERRQ(ierr); }
      ierr = PetscViewerASCIISynchronizedPrintf(viewer,"constraints errors\n");CHKERRQ(ierr);
      for(i=0;i<pcbddc->local_primal_size;i++) { ierr = PetscViewerASCIISynchronizedPrintf(viewer,"local %02d-th function error = % 1.14e\n",i,constraints_errors[i]);CHKERRQ(ierr); }
      ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
      ierr = MatDestroy(&A_II);CHKERRQ(ierr);
      ierr = MatDestroy(&A_BB);CHKERRQ(ierr);
      ierr = MatDestroy(&A_IB);CHKERRQ(ierr);
      ierr = MatDestroy(&A_BI);CHKERRQ(ierr);
      ierr = MatDestroy(&TM1);CHKERRQ(ierr);
      ierr = MatDestroy(&TM2);CHKERRQ(ierr);
      ierr = MatDestroy(&TM3);CHKERRQ(ierr);
      ierr = MatDestroy(&TM4);CHKERRQ(ierr);
      ierr = MatDestroy(&coarse_phi_D);CHKERRQ(ierr);
      ierr = MatDestroy(&coarse_sub_mat);CHKERRQ(ierr);
      ierr = MatDestroy(&coarse_phi_B);CHKERRQ(ierr);
      ierr = PetscFree(coarsefunctions_errors);CHKERRQ(ierr);
      ierr = PetscFree(constraints_errors);CHKERRQ(ierr);
    }

    /* create coarse matrix and data structures for message passing associated actual choice of coarse problem type */
    ierr = PCBDDCSetupCoarseEnvironment(pc,coarse_submat_vals);CHKERRQ(ierr);
    /* free memory */
    ierr = PetscFree(coarse_submat_vals);CHKERRQ(ierr);
    ierr = PetscFree(auxindices);CHKERRQ(ierr);
    ierr = PetscFree(nnz);CHKERRQ(ierr);
    if(n_vertices) {
      ierr = VecDestroy(&vec1_V);CHKERRQ(ierr);
      ierr = VecDestroy(&vec2_V);CHKERRQ(ierr);
      ierr = MatDestroy(&M2);CHKERRQ(ierr);
      ierr = MatDestroy(&A_RV);CHKERRQ(ierr);
      ierr = MatDestroy(&A_VR);CHKERRQ(ierr);
      ierr = MatDestroy(&A_VV);CHKERRQ(ierr);
    }
    if(pcbddc->n_constraints) {
      ierr = VecDestroy(&vec1_C);CHKERRQ(ierr);
      ierr = VecDestroy(&vec2_C);CHKERRQ(ierr);
      ierr = MatDestroy(&M1);CHKERRQ(ierr);
      ierr = MatDestroy(&C_CR);CHKERRQ(ierr);
    }
  }
  /* free memory */
  if(n_vertices) {
    ierr = PetscFree(idx_V_B);CHKERRQ(ierr);
    ierr = ISDestroy(&is_V_local);CHKERRQ(ierr);
  }
  ierr = PetscFree(idx_R_local);CHKERRQ(ierr);
  ierr = ISDestroy(&is_R_local);CHKERRQ(ierr);
  ierr = ISRestoreIndices(pcbddc->ISForVertices,(const PetscInt**)&vertices);CHKERRQ(ierr);

  PetscFunctionReturn(0);
}

/* -------------------------------------------------------------------------- */

#undef __FUNCT__
#define __FUNCT__ "PCBDDCSetupCoarseEnvironment"
static PetscErrorCode PCBDDCSetupCoarseEnvironment(PC pc,PetscScalar* coarse_submat_vals)
{


  Mat_IS    *matis    = (Mat_IS*)pc->pmat->data;
  PC_BDDC   *pcbddc   = (PC_BDDC*)pc->data;
  PC_IS     *pcis     = (PC_IS*)pc->data;
  MPI_Comm  prec_comm = ((PetscObject)pc)->comm;
  MPI_Comm  coarse_comm;

  /* common to all choiches */
  PetscScalar *temp_coarse_mat_vals;
  PetscScalar *ins_coarse_mat_vals;
  PetscInt    *ins_local_primal_indices;
  PetscMPIInt *localsizes2,*localdispl2;
  PetscMPIInt size_prec_comm;
  PetscMPIInt rank_prec_comm;
  PetscMPIInt active_rank=MPI_PROC_NULL;
  PetscMPIInt master_proc=0;
  PetscInt    ins_local_primal_size;
  /* specific to MULTILEVEL_BDDC */
  PetscMPIInt *ranks_recv;
  PetscMPIInt count_recv=0;
  PetscMPIInt rank_coarse_proc_send_to;
  PetscMPIInt coarse_color = MPI_UNDEFINED;
  ISLocalToGlobalMapping coarse_ISLG;
  /* some other variables */
  PetscErrorCode ierr;
  const MatType coarse_mat_type;
  const PCType  coarse_pc_type;
  const KSPType  coarse_ksp_type;
  PC pc_temp;
  PetscInt i,j,k,bs;
  PetscInt max_it_coarse_ksp=1;  /* don't increase this value */
  /* verbose output viewer */
  PetscViewer viewer=pcbddc->dbg_viewer;
  PetscBool   dbg_flag=pcbddc->dbg_flag;

  PetscFunctionBegin;

  ins_local_primal_indices = 0;
  ins_coarse_mat_vals      = 0;
  localsizes2              = 0;
  localdispl2              = 0;
  temp_coarse_mat_vals     = 0;
  coarse_ISLG              = 0;

  ierr = MPI_Comm_size(prec_comm,&size_prec_comm);CHKERRQ(ierr);
  ierr = MPI_Comm_rank(prec_comm,&rank_prec_comm);CHKERRQ(ierr);
  ierr = MatGetBlockSize(matis->A,&bs);CHKERRQ(ierr);

  /* Assign global numbering to coarse dofs */
  {
    PetscScalar    one=1.,zero=0.;
    PetscScalar    *array;
    PetscMPIInt    *auxlocal_primal;
    PetscMPIInt    *auxglobal_primal;
    PetscMPIInt    *all_auxglobal_primal;
    PetscMPIInt    *all_auxglobal_primal_dummy;
    PetscMPIInt    mpi_local_primal_size = (PetscMPIInt)pcbddc->local_primal_size;
    PetscInt       *vertices,*row_cmat_indices;
    PetscInt       size_of_constraint;

    /* Construct needed data structures for message passing */
    ierr = PetscMalloc(mpi_local_primal_size*sizeof(PetscMPIInt),&pcbddc->local_primal_indices);CHKERRQ(ierr);
    ierr = PetscMalloc(size_prec_comm*sizeof(PetscMPIInt),&pcbddc->local_primal_sizes);CHKERRQ(ierr);
    ierr = PetscMalloc(size_prec_comm*sizeof(PetscMPIInt),&pcbddc->local_primal_displacements);CHKERRQ(ierr);
    /* Gather local_primal_size information for all processes  */
    ierr = MPI_Allgather(&mpi_local_primal_size,1,MPIU_INT,&pcbddc->local_primal_sizes[0],1,MPIU_INT,prec_comm);CHKERRQ(ierr);
    pcbddc->replicated_primal_size = 0;
    for (i=0; i<size_prec_comm; i++) {
      pcbddc->local_primal_displacements[i] = pcbddc->replicated_primal_size ;
      pcbddc->replicated_primal_size += pcbddc->local_primal_sizes[i];
    }
    if(rank_prec_comm == 0) {
      /* allocate some auxiliary space */
      ierr = PetscMalloc(pcbddc->replicated_primal_size*sizeof(*all_auxglobal_primal),&all_auxglobal_primal);CHKERRQ(ierr);
      ierr = PetscMalloc(pcbddc->replicated_primal_size*sizeof(*all_auxglobal_primal_dummy),&all_auxglobal_primal_dummy);CHKERRQ(ierr);
    }
    ierr = PetscMalloc(pcbddc->local_primal_size*sizeof(PetscMPIInt),&auxlocal_primal);CHKERRQ(ierr);
    ierr = PetscMalloc(pcbddc->local_primal_size*sizeof(PetscMPIInt),&auxglobal_primal);CHKERRQ(ierr);

    /* First let's count coarse dofs: note that we allow to have a constraint on a subdomain and not its counterpart on the neighbour subdomain (if user wants)
       This code fragment assumes that the number of local constraints per connected component
       is not greater than the number of nodes defined for the connected component
       (otherwise we will surely have linear dependence between constraints and thus a singular coarse problem) */
    /* auxlocal_primal      : primal indices in local nodes numbering (internal and interface) with complete queue sorted by global ordering */
    ierr = VecSet(pcis->vec1_N,zero);CHKERRQ(ierr);
    ierr = ISGetIndices(pcbddc->ISForVertices,(const PetscInt**)&vertices);CHKERRQ(ierr);
    ierr = VecGetArray(pcis->vec1_N,&array);CHKERRQ(ierr);
    for(i=0;i<pcbddc->n_vertices;i++) {  /* note that  pcbddc->n_vertices can be different from size of ISForVertices */
      array[ vertices[i] ] = one;
      auxlocal_primal[i] = vertices[i];
    }
    ierr = ISRestoreIndices(pcbddc->ISForVertices,(const PetscInt**)&vertices);CHKERRQ(ierr);
    for(i=0;i<pcbddc->n_constraints;i++) {
      ierr = MatGetRow(pcbddc->ConstraintMatrix,pcbddc->n_vertices+i,&size_of_constraint,(const PetscInt**)&row_cmat_indices,PETSC_NULL);CHKERRQ(ierr);
      for (j=0; j<size_of_constraint; j++) {
        k = row_cmat_indices[j];
        if( array[k] == zero ) {
          array[k] = one;
          auxlocal_primal[i+pcbddc->n_vertices] = k;
          break;
        }
      }
      ierr = MatRestoreRow(pcbddc->ConstraintMatrix,pcbddc->n_vertices+i,&size_of_constraint,(const PetscInt**)&row_cmat_indices,PETSC_NULL);CHKERRQ(ierr);
    }
    ierr = VecRestoreArray(pcis->vec1_N,&array);CHKERRQ(ierr);

    /* Now assign them a global numbering */
    /* auxglobal_primal contains indices in global nodes numbering (internal and interface) */
    ierr = ISLocalToGlobalMappingApply(matis->mapping,pcbddc->local_primal_size,auxlocal_primal,auxglobal_primal);CHKERRQ(ierr);
    /* all_auxglobal_primal contains all primal nodes indices in global nodes numbering (internal and interface) */
    ierr = MPI_Gatherv(&auxglobal_primal[0],pcbddc->local_primal_size,MPIU_INT,&all_auxglobal_primal[0],pcbddc->local_primal_sizes,pcbddc->local_primal_displacements,MPIU_INT,0,prec_comm);CHKERRQ(ierr);

    /* After this block all_auxglobal_primal should contains one copy of each primal node's indices in global nodes numbering */
    /* It implements a function similar to PetscSortRemoveDupsInt */
    if(rank_prec_comm==0) {
      /* dummy argument since PetscSortMPIInt doesn't exist! */
      ierr = PetscSortMPIIntWithArray(pcbddc->replicated_primal_size,all_auxglobal_primal,all_auxglobal_primal_dummy);CHKERRQ(ierr);
      k=1;
      j=all_auxglobal_primal[0];  /* first dof in global numbering */
      for(i=1;i< pcbddc->replicated_primal_size ;i++) {
        if(j != all_auxglobal_primal[i] ) {
          all_auxglobal_primal[k]=all_auxglobal_primal[i];
          k++;
          j=all_auxglobal_primal[i];
        }
      }
    } else {
      ierr = PetscMalloc(pcbddc->coarse_size*sizeof(PetscMPIInt),&all_auxglobal_primal);CHKERRQ(ierr);
    }
    /* We only need to broadcast the indices from 0 to pcbddc->coarse_size. Remaning elements of array all_aux_global_primal are garbage. */
    ierr = MPI_Bcast(all_auxglobal_primal,pcbddc->coarse_size,MPIU_INT,0,prec_comm);CHKERRQ(ierr);

    /* Now get global coarse numbering of local primal nodes */
    for(i=0;i<pcbddc->local_primal_size;i++) {
      k=0;
      while( all_auxglobal_primal[k] != auxglobal_primal[i] ) { k++;}
      pcbddc->local_primal_indices[i]=k;
    }
    if(dbg_flag) {
      ierr = PetscViewerASCIIPrintf(viewer,"--------------------------------------------------\n");CHKERRQ(ierr);
      ierr = PetscViewerASCIIPrintf(viewer,"Distribution of local primal indices\n");CHKERRQ(ierr);
      ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
      ierr = PetscViewerASCIISynchronizedPrintf(viewer,"Subdomain %04d\n",PetscGlobalRank);CHKERRQ(ierr);
      for(i=0;i<pcbddc->local_primal_size;i++) {
        ierr = PetscViewerASCIISynchronizedPrintf(viewer,"local_primal_indices[%d]=%d \n",i,pcbddc->local_primal_indices[i]);
      }
      ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
    }
    /* free allocated memory */
    ierr = PetscFree(auxlocal_primal);CHKERRQ(ierr);
    ierr = PetscFree(auxglobal_primal);CHKERRQ(ierr);
    ierr = PetscFree(all_auxglobal_primal);CHKERRQ(ierr);
    if(rank_prec_comm == 0) {
      ierr = PetscFree(all_auxglobal_primal_dummy);CHKERRQ(ierr);
    }
  }

  /* adapt coarse problem type */
  if(pcbddc->coarse_problem_type == MULTILEVEL_BDDC && pcbddc->active_procs < MIN_PROCS_FOR_BDDC )
    pcbddc->coarse_problem_type = PARALLEL_BDDC;

  switch(pcbddc->coarse_problem_type){

    case(MULTILEVEL_BDDC):   //we define a coarse mesh where subdomains are elements
    {
      /* we need additional variables */
      MetisInt   n_subdomains,n_parts,objval,ncon,faces_nvtxs;
      MetisInt   *metis_coarse_subdivision;
      MetisInt   options[METIS_NOPTIONS];
      PetscMPIInt size_coarse_comm,rank_coarse_comm;
      PetscMPIInt procs_jumps_coarse_comm;
      PetscMPIInt *coarse_subdivision;
      PetscMPIInt *total_count_recv;
      PetscMPIInt *total_ranks_recv;
      PetscMPIInt *displacements_recv;
      PetscMPIInt *my_faces_connectivity;
      PetscMPIInt *petsc_faces_adjncy;
      MetisInt    *faces_adjncy;
      MetisInt    *faces_xadj;
      PetscMPIInt *number_of_faces;
      PetscMPIInt *faces_displacements;
      PetscInt    *array_int;
      PetscMPIInt my_faces=0;
      PetscMPIInt total_faces=0;
      PetscInt    ranks_stretching_ratio;

      /* define some quantities */
      pcbddc->coarse_communications_type = SCATTERS_BDDC;
      coarse_mat_type = MATIS;
      coarse_pc_type  = PCBDDC;
      coarse_ksp_type  = KSPCHEBYCHEV;

      /* details of coarse decomposition */
      n_subdomains = pcbddc->active_procs;
      n_parts      = n_subdomains/pcbddc->coarsening_ratio;
      ranks_stretching_ratio = size_prec_comm/pcbddc->active_procs;
      procs_jumps_coarse_comm = pcbddc->coarsening_ratio*ranks_stretching_ratio;

      printf("Coarse algorithm details: \n");
      printf("n_subdomains %d, n_parts %d\nstretch %d,jumps %d,coarse_ratio %d\nlevel should be log_%d(%d)\n",n_subdomains,n_parts,ranks_stretching_ratio,procs_jumps_coarse_comm,pcbddc->coarsening_ratio,pcbddc->coarsening_ratio,(ranks_stretching_ratio/pcbddc->coarsening_ratio+1));

      /* build CSR graph of subdomains' connectivity through faces */
      ierr = PetscMalloc (pcis->n*sizeof(PetscInt),&array_int);CHKERRQ(ierr);
      ierr = PetscMemzero(array_int,pcis->n*sizeof(PetscInt));CHKERRQ(ierr);
      for(i=1;i<pcis->n_neigh;i++){/* i=1 so I don't count myself -> faces nodes counts to 1 */
        for(j=0;j<pcis->n_shared[i];j++){
          array_int[ pcis->shared[i][j] ]+=1;
        }
      }
      for(i=1;i<pcis->n_neigh;i++){
        for(j=0;j<pcis->n_shared[i];j++){
          if(array_int[ pcis->shared[i][j] ] == 1 ){
            my_faces++;
            break;
          }
        }
      }
      //printf("I found %d faces.\n",my_faces);

      ierr = MPI_Reduce(&my_faces,&total_faces,1,MPIU_INT,MPI_SUM,master_proc,prec_comm);CHKERRQ(ierr);
      ierr = PetscMalloc (my_faces*sizeof(PetscInt),&my_faces_connectivity);CHKERRQ(ierr);
      my_faces=0;
      for(i=1;i<pcis->n_neigh;i++){
        for(j=0;j<pcis->n_shared[i];j++){
          if(array_int[ pcis->shared[i][j] ] == 1 ){
            my_faces_connectivity[my_faces]=pcis->neigh[i];
            my_faces++;
            break;
          }
        }
      }
      if(rank_prec_comm == master_proc) {
        //printf("I found %d total faces.\n",total_faces);
        ierr = PetscMalloc (total_faces*sizeof(PetscMPIInt),&petsc_faces_adjncy);CHKERRQ(ierr);
        ierr = PetscMalloc (size_prec_comm*sizeof(PetscMPIInt),&number_of_faces);CHKERRQ(ierr);
        ierr = PetscMalloc (total_faces*sizeof(MetisInt),&faces_adjncy);CHKERRQ(ierr);
        ierr = PetscMalloc ((n_subdomains+1)*sizeof(MetisInt),&faces_xadj);CHKERRQ(ierr);
        ierr = PetscMalloc ((size_prec_comm+1)*sizeof(PetscMPIInt),&faces_displacements);CHKERRQ(ierr);
      }
      ierr = MPI_Gather(&my_faces,1,MPIU_INT,&number_of_faces[0],1,MPIU_INT,master_proc,prec_comm);CHKERRQ(ierr);
      if(rank_prec_comm == master_proc) {
        faces_xadj[0]=0;
        faces_displacements[0]=0;
        j=0;
        for(i=1;i<size_prec_comm+1;i++) {
          faces_displacements[i]=faces_displacements[i-1]+number_of_faces[i-1];
          if(number_of_faces[i-1]) {
            j++;
            faces_xadj[j]=faces_xadj[j-1]+number_of_faces[i-1];
          }
        }
        printf("The J I count is %d and should be %d\n",j,n_subdomains);
        printf("Total faces seem %d and should be %d\n",faces_xadj[j],total_faces);
      }
      ierr = MPI_Gatherv(&my_faces_connectivity[0],my_faces,MPIU_INT,&petsc_faces_adjncy[0],number_of_faces,faces_displacements,MPIU_INT,master_proc,prec_comm);CHKERRQ(ierr);
      ierr = PetscFree(my_faces_connectivity);CHKERRQ(ierr);
      ierr = PetscFree(array_int);CHKERRQ(ierr);
      if(rank_prec_comm == master_proc) {
        for(i=0;i<total_faces;i++) faces_adjncy[i]=(MetisInt)(petsc_faces_adjncy[i]/ranks_stretching_ratio); /* cast to MetisInt */
        printf("This is the face connectivity (actual ranks)\n");
        for(i=0;i<n_subdomains;i++){
          printf("proc %d is connected with \n",i);
          for(j=faces_xadj[i];j<faces_xadj[i+1];j++)
            printf("%d ",faces_adjncy[j]);
          printf("\n");
        }
        ierr = PetscFree(faces_displacements);CHKERRQ(ierr);
        ierr = PetscFree(number_of_faces);CHKERRQ(ierr);
        ierr = PetscFree(petsc_faces_adjncy);CHKERRQ(ierr);
      }

      if( rank_prec_comm == master_proc ) {

        PetscInt heuristic_for_metis=3;

        ncon=1;
        faces_nvtxs=n_subdomains;
        /* partition graoh induced by face connectivity */
        ierr = PetscMalloc (n_subdomains*sizeof(MetisInt),&metis_coarse_subdivision);CHKERRQ(ierr);
        ierr = METIS_SetDefaultOptions(options);
        /* we need a contiguous partition of the coarse mesh */
        options[METIS_OPTION_CONTIG]=1;
        options[METIS_OPTION_DBGLVL]=1;
        options[METIS_OPTION_NITER]=30;
        //options[METIS_OPTION_NCUTS]=1;
        printf("METIS PART GRAPH\n");
        if(n_subdomains>n_parts*heuristic_for_metis) {
          printf("Using Kway\n");
          options[METIS_OPTION_IPTYPE]=METIS_IPTYPE_EDGE;
          options[METIS_OPTION_OBJTYPE]=METIS_OBJTYPE_CUT;
          ierr = METIS_PartGraphKway(&faces_nvtxs,&ncon,faces_xadj,faces_adjncy,NULL,NULL,NULL,&n_parts,NULL,NULL,options,&objval,metis_coarse_subdivision);
        } else {
          printf("Using Recursive\n");
          ierr = METIS_PartGraphRecursive(&faces_nvtxs,&ncon,faces_xadj,faces_adjncy,NULL,NULL,NULL,&n_parts,NULL,NULL,options,&objval,metis_coarse_subdivision);
        }
        if(ierr != METIS_OK) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in METIS_PartGraphKway (metis error code %D) called from PCBDDCSetupCoarseEnvironment\n",ierr);
        printf("Partition done!\n");
        ierr = PetscFree(faces_xadj);CHKERRQ(ierr);
        ierr = PetscFree(faces_adjncy);CHKERRQ(ierr);
        coarse_subdivision = (PetscMPIInt*)calloc(size_prec_comm,sizeof(PetscMPIInt)); /* calloc for contiguous memory since we need to scatter these values later */
        /* copy/cast values avoiding possible type conflicts between PETSc, MPI and METIS */
        for(i=0;i<size_prec_comm;i++) coarse_subdivision[i]=MPI_PROC_NULL;
        for(i=0;i<n_subdomains;i++)   coarse_subdivision[ranks_stretching_ratio*i]=(PetscInt)(metis_coarse_subdivision[i]);
        ierr = PetscFree(metis_coarse_subdivision);CHKERRQ(ierr);
      }

      /* Create new communicator for coarse problem splitting the old one */
      if( !(rank_prec_comm%procs_jumps_coarse_comm) && rank_prec_comm < procs_jumps_coarse_comm*n_parts ){
        coarse_color=0;              //for communicator splitting
        active_rank=rank_prec_comm;  //for insertion of matrix values
      }
      // procs with coarse_color = MPI_UNDEFINED will have coarse_comm = MPI_COMM_NULL (from mpi standards)
      // key = rank_prec_comm -> keep same ordering of ranks from the old to the new communicator
      ierr = MPI_Comm_split(prec_comm,coarse_color,rank_prec_comm,&coarse_comm);CHKERRQ(ierr);

      if( coarse_color == 0 ) {
        ierr = MPI_Comm_size(coarse_comm,&size_coarse_comm);CHKERRQ(ierr);
        ierr = MPI_Comm_rank(coarse_comm,&rank_coarse_comm);CHKERRQ(ierr);
        printf("Details of coarse comm\n");
        printf("size = %d, myrank = %d\n",size_coarse_comm,rank_coarse_comm);
        printf("jumps = %d, coarse_color = %d, n_parts = %d\n",procs_jumps_coarse_comm,coarse_color,n_parts);
      } else {
        rank_coarse_comm = MPI_PROC_NULL;
      }

      /* master proc take care of arranging and distributing coarse informations */
      if(rank_coarse_comm == master_proc) {
        ierr = PetscMalloc (size_coarse_comm*sizeof(PetscMPIInt),&displacements_recv);CHKERRQ(ierr);
        //ierr = PetscMalloc (size_coarse_comm*sizeof(PetscMPIInt),&total_count_recv);CHKERRQ(ierr);
        //ierr = PetscMalloc (n_subdomains*sizeof(PetscMPIInt),&total_ranks_recv);CHKERRQ(ierr);
        total_count_recv = (PetscMPIInt*)calloc(size_prec_comm,sizeof(PetscMPIInt));
        total_ranks_recv = (PetscMPIInt*)calloc(n_subdomains,sizeof(PetscMPIInt));
        /* some initializations */
        displacements_recv[0]=0;
        //PetscMemzero(total_count_recv,size_coarse_comm*sizeof(PetscMPIInt)); not needed -> calloc initializes to zero
        /* count from how many processes the j-th process of the coarse decomposition will receive data */
        for(j=0;j<size_coarse_comm;j++)
          for(i=0;i<size_prec_comm;i++)
            if(coarse_subdivision[i]==j)
              total_count_recv[j]++;
        /* displacements needed for scatterv of total_ranks_recv */
        for(i=1;i<size_coarse_comm;i++) displacements_recv[i]=displacements_recv[i-1]+total_count_recv[i-1];
        /* Now fill properly total_ranks_recv -> each coarse process will receive the ranks (in prec_comm communicator) of its friend (sending) processes */
        ierr = PetscMemzero(total_count_recv,size_coarse_comm*sizeof(PetscMPIInt));CHKERRQ(ierr);
        for(j=0;j<size_coarse_comm;j++) {
          for(i=0;i<size_prec_comm;i++) {
            if(coarse_subdivision[i]==j) {
              total_ranks_recv[displacements_recv[j]+total_count_recv[j]]=i;
              total_count_recv[j]+=1;
            }
          }
        }
        for(j=0;j<size_coarse_comm;j++) {
          printf("process %d in new rank will receive from %d processes (original ranks follows)\n",j,total_count_recv[j]);
          for(i=0;i<total_count_recv[j];i++) {
            printf("%d ",total_ranks_recv[displacements_recv[j]+i]);
          }
          printf("\n");
        }

        /* identify new decomposition in terms of ranks in the old communicator */
        for(i=0;i<n_subdomains;i++) coarse_subdivision[ranks_stretching_ratio*i]=coarse_subdivision[ranks_stretching_ratio*i]*procs_jumps_coarse_comm;
        printf("coarse_subdivision in old end new ranks\n");
        for(i=0;i<size_prec_comm;i++)
          if(coarse_subdivision[i]!=MPI_PROC_NULL) {
            printf("%d=(%d %d), ",i,coarse_subdivision[i],coarse_subdivision[i]/procs_jumps_coarse_comm);
          } else {
            printf("%d=(%d %d), ",i,coarse_subdivision[i],coarse_subdivision[i]);
          }
        printf("\n");
      }

      /* Scatter new decomposition for send details */
      ierr = MPI_Scatter(&coarse_subdivision[0],1,MPIU_INT,&rank_coarse_proc_send_to,1,MPIU_INT,master_proc,prec_comm);CHKERRQ(ierr);
      /* Scatter receiving details to members of coarse decomposition */
      if( coarse_color == 0) {
        ierr = MPI_Scatter(&total_count_recv[0],1,MPIU_INT,&count_recv,1,MPIU_INT,master_proc,coarse_comm);CHKERRQ(ierr);
        ierr = PetscMalloc (count_recv*sizeof(PetscMPIInt),&ranks_recv);CHKERRQ(ierr);
        ierr = MPI_Scatterv(&total_ranks_recv[0],total_count_recv,displacements_recv,MPIU_INT,&ranks_recv[0],count_recv,MPIU_INT,master_proc,coarse_comm);CHKERRQ(ierr);
      }

      //printf("I will send my matrix data to proc  %d\n",rank_coarse_proc_send_to);
      //if(coarse_color == 0) {
      //  printf("I will receive some matrix data from %d processes (ranks follows)\n",count_recv);
      //  for(i=0;i<count_recv;i++)
      //    printf("%d ",ranks_recv[i]);
      //  printf("\n");
      //}

      if(rank_prec_comm == master_proc) {
        //ierr = PetscFree(coarse_subdivision);CHKERRQ(ierr);
        //ierr = PetscFree(total_count_recv);CHKERRQ(ierr);
        //ierr = PetscFree(total_ranks_recv);CHKERRQ(ierr);
        free(coarse_subdivision);
        free(total_count_recv);
        free(total_ranks_recv);
        ierr = PetscFree(displacements_recv);CHKERRQ(ierr);
      }
      break;
    }

    case(REPLICATED_BDDC):

      pcbddc->coarse_communications_type = GATHERS_BDDC;
      coarse_mat_type = MATSEQAIJ;
      coarse_pc_type  = PCLU;
      coarse_ksp_type  = KSPPREONLY;
      coarse_comm = PETSC_COMM_SELF;
      active_rank = rank_prec_comm;
      break;

    case(PARALLEL_BDDC):

      pcbddc->coarse_communications_type = SCATTERS_BDDC;
      coarse_mat_type = MATMPIAIJ;
      coarse_pc_type  = PCREDUNDANT;
      coarse_ksp_type  = KSPPREONLY;
      coarse_comm = prec_comm;
      active_rank = rank_prec_comm;
      break;

    case(SEQUENTIAL_BDDC):
      pcbddc->coarse_communications_type = GATHERS_BDDC;
      coarse_mat_type = MATSEQAIJ;
      coarse_pc_type = PCLU;
      coarse_ksp_type  = KSPPREONLY;
      coarse_comm = PETSC_COMM_SELF;
      active_rank = master_proc;
      break;
  }

  switch(pcbddc->coarse_communications_type){

    case(SCATTERS_BDDC):
      {
        if(pcbddc->coarse_problem_type==MULTILEVEL_BDDC) {

          PetscMPIInt send_size;
          PetscInt    *aux_ins_indices;
          PetscInt    ii,jj;
          MPI_Request *requests;

          /* allocate auxiliary space */
          ierr = PetscMalloc (pcbddc->replicated_primal_size*sizeof(PetscMPIInt),&pcbddc->replicated_local_primal_indices);CHKERRQ(ierr);
          ierr = MPI_Allgatherv(&pcbddc->local_primal_indices[0],pcbddc->local_primal_size,MPIU_INT,&pcbddc->replicated_local_primal_indices[0],pcbddc->local_primal_sizes,pcbddc->local_primal_displacements,MPIU_INT,prec_comm);CHKERRQ(ierr);
          ierr = PetscMalloc ( pcbddc->coarse_size*sizeof(PetscInt),&aux_ins_indices);CHKERRQ(ierr);
          ierr = PetscMemzero(aux_ins_indices,pcbddc->coarse_size*sizeof(PetscInt));CHKERRQ(ierr);
          /* allocate stuffs for message massing */
          ierr = PetscMalloc ( (count_recv+1)*sizeof(MPI_Request),&requests);CHKERRQ(ierr);
          for(i=0;i<count_recv+1;i++) requests[i]=MPI_REQUEST_NULL;
          ierr = PetscMalloc ( count_recv*sizeof(PetscMPIInt),&localsizes2);CHKERRQ(ierr);
          ierr = PetscMalloc ( count_recv*sizeof(PetscMPIInt),&localdispl2);CHKERRQ(ierr);
          /* fill up quantities */
          j=0;
          for(i=0;i<count_recv;i++){
            ii = ranks_recv[i];
            localsizes2[i]=pcbddc->local_primal_sizes[ii]*pcbddc->local_primal_sizes[ii];
            localdispl2[i]=j;
            j+=localsizes2[i];
            jj = pcbddc->local_primal_displacements[ii];
            for(k=0;k<pcbddc->local_primal_sizes[ii];k++) aux_ins_indices[pcbddc->replicated_local_primal_indices[jj+k]]+=1;  // it counts the coarse subdomains sharing the coarse node
          }
          //printf("aux_ins_indices 1\n");
          //for(i=0;i<pcbddc->coarse_size;i++)
          //  printf("%d ",aux_ins_indices[i]);
          //printf("\n");
          /* temp_coarse_mat_vals used to store temporarly received matrix values */
          ierr = PetscMalloc ( j*sizeof(PetscScalar),&temp_coarse_mat_vals);CHKERRQ(ierr);
          /* evaluate how many values I will insert in coarse mat */
          ins_local_primal_size=0;
          for(i=0;i<pcbddc->coarse_size;i++)
            if(aux_ins_indices[i])
              ins_local_primal_size++;
          /* evaluate indices I will insert in coarse mat */
          ierr = PetscMalloc ( ins_local_primal_size*sizeof(PetscInt),&ins_local_primal_indices);CHKERRQ(ierr);
          j=0;
          for(i=0;i<pcbddc->coarse_size;i++)
            if(aux_ins_indices[i])
              ins_local_primal_indices[j++]=i;
          /* use aux_ins_indices to realize a global to local mapping */
          j=0;
          for(i=0;i<pcbddc->coarse_size;i++){
            if(aux_ins_indices[i]==0){
              aux_ins_indices[i]=-1;
            } else {
              aux_ins_indices[i]=j;
              j++;
            }
          }

          //printf("New details localsizes2 localdispl2\n");
          //for(i=0;i<count_recv;i++)
          //  printf("(%d %d) ",localsizes2[i],localdispl2[i]);
          //printf("\n");
          //printf("aux_ins_indices 2\n");
          //for(i=0;i<pcbddc->coarse_size;i++)
          //  printf("%d ",aux_ins_indices[i]);
          //printf("\n");
          //printf("ins_local_primal_indices\n");
          //for(i=0;i<ins_local_primal_size;i++)
          //  printf("%d ",ins_local_primal_indices[i]);
          //printf("\n");
          //printf("coarse_submat_vals\n");
          //for(i=0;i<pcbddc->local_primal_size;i++)
          //  for(j=0;j<pcbddc->local_primal_size;j++)
          //    printf("(%lf %d %d)\n",coarse_submat_vals[j*pcbddc->local_primal_size+i],pcbddc->local_primal_indices[i],pcbddc->local_primal_indices[j]);
          //printf("\n");

          /* processes partecipating in coarse problem receive matrix data from their friends */
          for(i=0;i<count_recv;i++) ierr = MPI_Irecv(&temp_coarse_mat_vals[localdispl2[i]],localsizes2[i],MPIU_SCALAR,ranks_recv[i],666,prec_comm,&requests[i]);CHKERRQ(ierr);
          if(rank_coarse_proc_send_to != MPI_PROC_NULL ) {
            send_size=pcbddc->local_primal_size*pcbddc->local_primal_size;
            ierr = MPI_Isend(&coarse_submat_vals[0],send_size,MPIU_SCALAR,rank_coarse_proc_send_to,666,prec_comm,&requests[count_recv]);CHKERRQ(ierr);
          }
          ierr = MPI_Waitall(count_recv+1,requests,MPI_STATUSES_IGNORE);CHKERRQ(ierr);

          //if(coarse_color == 0) {
          //  printf("temp_coarse_mat_vals\n");
          //  for(k=0;k<count_recv;k++){
          //    printf("---- %d ----\n",ranks_recv[k]);
          //    for(i=0;i<pcbddc->local_primal_sizes[ranks_recv[k]];i++)
          //      for(j=0;j<pcbddc->local_primal_sizes[ranks_recv[k]];j++)
          //        printf("(%lf %d %d)\n",temp_coarse_mat_vals[localdispl2[k]+j*pcbddc->local_primal_sizes[ranks_recv[k]]+i],pcbddc->replicated_local_primal_indices[pcbddc->local_primal_displacements[ranks_recv[k]]+i],pcbddc->replicated_local_primal_indices[pcbddc->local_primal_displacements[ranks_recv[k]]+j]);
          //    printf("\n");
          //  }
          //}
          /* calculate data to insert in coarse mat */
          ierr = PetscMalloc ( ins_local_primal_size*ins_local_primal_size*sizeof(PetscScalar),&ins_coarse_mat_vals);CHKERRQ(ierr);
          PetscMemzero(ins_coarse_mat_vals,ins_local_primal_size*ins_local_primal_size*sizeof(PetscScalar));

          PetscMPIInt rr,kk,lps,lpd;
          PetscInt row_ind,col_ind;
          for(k=0;k<count_recv;k++){
            rr = ranks_recv[k];
            kk = localdispl2[k];
            lps = pcbddc->local_primal_sizes[rr];
            lpd = pcbddc->local_primal_displacements[rr];
            //printf("Inserting the following indices (received from %d)\n",rr);
            for(j=0;j<lps;j++){
              col_ind=aux_ins_indices[pcbddc->replicated_local_primal_indices[lpd+j]];
              for(i=0;i<lps;i++){
                row_ind=aux_ins_indices[pcbddc->replicated_local_primal_indices[lpd+i]];
                //printf("%d %d\n",row_ind,col_ind);
                ins_coarse_mat_vals[col_ind*ins_local_primal_size+row_ind]+=temp_coarse_mat_vals[kk+j*lps+i];
              }
            }
          }
          ierr = PetscFree(requests);CHKERRQ(ierr);
          ierr = PetscFree(aux_ins_indices);CHKERRQ(ierr);
          ierr = PetscFree(temp_coarse_mat_vals);CHKERRQ(ierr);
          if(coarse_color == 0) { ierr = PetscFree(ranks_recv);CHKERRQ(ierr); }

          /* create local to global mapping needed by coarse MATIS */
          {
            IS coarse_IS;
            if(coarse_comm != MPI_COMM_NULL ) ierr = MPI_Comm_free(&coarse_comm);CHKERRQ(ierr);
            coarse_comm = prec_comm;
            active_rank=rank_prec_comm;
            ierr = ISCreateGeneral(coarse_comm,ins_local_primal_size,ins_local_primal_indices,PETSC_COPY_VALUES,&coarse_IS);CHKERRQ(ierr);
            ierr = ISLocalToGlobalMappingCreateIS(coarse_IS,&coarse_ISLG);CHKERRQ(ierr);
            ierr = ISDestroy(&coarse_IS);CHKERRQ(ierr);
          }
        }
        if(pcbddc->coarse_problem_type==PARALLEL_BDDC) {
          /* arrays for values insertion */
          ins_local_primal_size = pcbddc->local_primal_size;
          ierr = PetscMalloc ( ins_local_primal_size*sizeof(PetscMPIInt),&ins_local_primal_indices);CHKERRQ(ierr);
          ierr = PetscMalloc ( ins_local_primal_size*ins_local_primal_size*sizeof(PetscScalar),&ins_coarse_mat_vals);CHKERRQ(ierr);
          for(j=0;j<ins_local_primal_size;j++){
            ins_local_primal_indices[j]=pcbddc->local_primal_indices[j];
            for(i=0;i<ins_local_primal_size;i++) ins_coarse_mat_vals[j*ins_local_primal_size+i]=coarse_submat_vals[j*ins_local_primal_size+i];
          }
        }
        break;

    }

    case(GATHERS_BDDC):
      {

        PetscMPIInt mysize,mysize2;

        if(rank_prec_comm==active_rank) {
          ierr = PetscMalloc ( pcbddc->replicated_primal_size*sizeof(PetscMPIInt),&pcbddc->replicated_local_primal_indices);CHKERRQ(ierr);
          pcbddc->replicated_local_primal_values = (PetscScalar*)calloc(pcbddc->replicated_primal_size,sizeof(PetscScalar));
          ierr = PetscMalloc ( size_prec_comm*sizeof(PetscMPIInt),&localsizes2);CHKERRQ(ierr);
          ierr = PetscMalloc ( size_prec_comm*sizeof(PetscMPIInt),&localdispl2);CHKERRQ(ierr);
          /* arrays for values insertion */
          ins_local_primal_size = pcbddc->coarse_size;
          ierr = PetscMalloc ( ins_local_primal_size*sizeof(PetscMPIInt),&ins_local_primal_indices);CHKERRQ(ierr);
          ierr = PetscMalloc ( ins_local_primal_size*ins_local_primal_size*sizeof(PetscScalar),&ins_coarse_mat_vals);CHKERRQ(ierr);
          for(i=0;i<size_prec_comm;i++) localsizes2[i]=pcbddc->local_primal_sizes[i]*pcbddc->local_primal_sizes[i];
          localdispl2[0]=0;
          for(i=1;i<size_prec_comm;i++) localdispl2[i]=localsizes2[i-1]+localdispl2[i-1];
          j=0;
          for(i=0;i<size_prec_comm;i++) j+=localsizes2[i];
          ierr = PetscMalloc ( j*sizeof(PetscScalar),&temp_coarse_mat_vals);CHKERRQ(ierr);
        }

        mysize=pcbddc->local_primal_size;
        mysize2=pcbddc->local_primal_size*pcbddc->local_primal_size;
        if(pcbddc->coarse_problem_type == SEQUENTIAL_BDDC){
          ierr = MPI_Gatherv(&pcbddc->local_primal_indices[0],mysize,MPIU_INT,&pcbddc->replicated_local_primal_indices[0],pcbddc->local_primal_sizes,pcbddc->local_primal_displacements,MPIU_INT,master_proc,prec_comm);CHKERRQ(ierr);
          ierr = MPI_Gatherv(&coarse_submat_vals[0],mysize2,MPIU_SCALAR,&temp_coarse_mat_vals[0],localsizes2,localdispl2,MPIU_SCALAR,master_proc,prec_comm);CHKERRQ(ierr);
        } else {
          ierr = MPI_Allgatherv(&pcbddc->local_primal_indices[0],mysize,MPIU_INT,&pcbddc->replicated_local_primal_indices[0],pcbddc->local_primal_sizes,pcbddc->local_primal_displacements,MPIU_INT,prec_comm);CHKERRQ(ierr);
          ierr = MPI_Allgatherv(&coarse_submat_vals[0],mysize2,MPIU_SCALAR,&temp_coarse_mat_vals[0],localsizes2,localdispl2,MPIU_SCALAR,prec_comm);CHKERRQ(ierr);
        }

  /* free data structures no longer needed and allocate some space which will be needed in BDDC application */
        if(rank_prec_comm==active_rank) {
          PetscInt offset,offset2,row_ind,col_ind;
          for(j=0;j<ins_local_primal_size;j++){
            ins_local_primal_indices[j]=j;
            for(i=0;i<ins_local_primal_size;i++) ins_coarse_mat_vals[j*ins_local_primal_size+i]=0.0;
          }
          for(k=0;k<size_prec_comm;k++){
            offset=pcbddc->local_primal_displacements[k];
            offset2=localdispl2[k];
            for(j=0;j<pcbddc->local_primal_sizes[k];j++){
              col_ind=pcbddc->replicated_local_primal_indices[offset+j];
              for(i=0;i<pcbddc->local_primal_sizes[k];i++){
                row_ind=pcbddc->replicated_local_primal_indices[offset+i];
                ins_coarse_mat_vals[col_ind*pcbddc->coarse_size+row_ind]+=temp_coarse_mat_vals[offset2+j*pcbddc->local_primal_sizes[k]+i];
              }
            }
          }
        }
        break;
      }//switch on coarse problem and communications associated with finished
  }

  /* Now create and fill up coarse matrix */
  if( rank_prec_comm == active_rank ) {
    if(pcbddc->coarse_problem_type != MULTILEVEL_BDDC) {
      ierr = MatCreate(coarse_comm,&pcbddc->coarse_mat);CHKERRQ(ierr);
      ierr = MatSetSizes(pcbddc->coarse_mat,PETSC_DECIDE,PETSC_DECIDE,pcbddc->coarse_size,pcbddc->coarse_size);CHKERRQ(ierr);
      ierr = MatSetType(pcbddc->coarse_mat,coarse_mat_type);CHKERRQ(ierr);
      ierr = MatSetUp(pcbddc->coarse_mat);CHKERRQ(ierr);
      ierr = MatSetOption(pcbddc->coarse_mat,MAT_ROW_ORIENTED,PETSC_FALSE);CHKERRQ(ierr); //local values stored in column major
      ierr = MatSetOption(pcbddc->coarse_mat,MAT_IGNORE_ZERO_ENTRIES,PETSC_TRUE);CHKERRQ(ierr);
    } else {
      Mat matis_coarse_local_mat;
      /* remind bs */
      ierr = MatCreateIS(coarse_comm,bs,PETSC_DECIDE,PETSC_DECIDE,pcbddc->coarse_size,pcbddc->coarse_size,coarse_ISLG,&pcbddc->coarse_mat);CHKERRQ(ierr);
      ierr = MatSetUp(pcbddc->coarse_mat);CHKERRQ(ierr);
      ierr = MatISGetLocalMat(pcbddc->coarse_mat,&matis_coarse_local_mat);CHKERRQ(ierr);
      ierr = MatSetUp(matis_coarse_local_mat);CHKERRQ(ierr);
      ierr = MatSetOption(matis_coarse_local_mat,MAT_ROW_ORIENTED,PETSC_FALSE);CHKERRQ(ierr); //local values stored in column major
      ierr = MatSetOption(matis_coarse_local_mat,MAT_IGNORE_ZERO_ENTRIES,PETSC_TRUE);CHKERRQ(ierr);
    }
    ierr = MatSetOption(pcbddc->coarse_mat,MAT_NEW_NONZERO_LOCATION_ERR,PETSC_FALSE);CHKERRQ(ierr);
    ierr = MatSetValues(pcbddc->coarse_mat,ins_local_primal_size,ins_local_primal_indices,ins_local_primal_size,ins_local_primal_indices,ins_coarse_mat_vals,ADD_VALUES);CHKERRQ(ierr);
    ierr = MatAssemblyBegin(pcbddc->coarse_mat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
    ierr = MatAssemblyEnd(pcbddc->coarse_mat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);

    ierr = MatGetVecs(pcbddc->coarse_mat,&pcbddc->coarse_vec,&pcbddc->coarse_rhs);CHKERRQ(ierr);
    /* Preconditioner for coarse problem */
    ierr = KSPCreate(coarse_comm,&pcbddc->coarse_ksp);CHKERRQ(ierr);
    ierr = PetscObjectIncrementTabLevel((PetscObject)pcbddc->coarse_ksp,(PetscObject)pc,1);CHKERRQ(ierr);
    ierr = KSPSetOperators(pcbddc->coarse_ksp,pcbddc->coarse_mat,pcbddc->coarse_mat,SAME_PRECONDITIONER);CHKERRQ(ierr);
    ierr = KSPSetTolerances(pcbddc->coarse_ksp,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT,max_it_coarse_ksp);CHKERRQ(ierr);
    ierr = KSPSetType(pcbddc->coarse_ksp,coarse_ksp_type);CHKERRQ(ierr);
    ierr = KSPGetPC(pcbddc->coarse_ksp,&pc_temp);CHKERRQ(ierr);
    ierr = PCSetType(pc_temp,coarse_pc_type);CHKERRQ(ierr);
    /* Allow user's customization */
    ierr = KSPSetFromOptions(pcbddc->coarse_ksp);CHKERRQ(ierr);
    /* Set Up PC for coarse problem BDDC */
    if(pcbddc->coarse_problem_type == MULTILEVEL_BDDC) {
      if(dbg_flag) {
        ierr = PetscViewerASCIIPrintf(viewer,"----------------Setting up a new level---------------\n");CHKERRQ(ierr);
        ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
      }
      ierr = PCBDDCSetCoarseProblemType(pc_temp,MULTILEVEL_BDDC);CHKERRQ(ierr);
    }
    ierr = KSPSetUp(pcbddc->coarse_ksp);CHKERRQ(ierr);
    if(pcbddc->coarse_problem_type == MULTILEVEL_BDDC) {
      if(dbg_flag) {
        ierr = PetscViewerASCIIPrintf(viewer,"----------------New level set------------------------\n");CHKERRQ(ierr);
        ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
      }
    }
  }
  if(pcbddc->coarse_communications_type == SCATTERS_BDDC) {
     IS local_IS,global_IS;
     ierr = ISCreateStride(PETSC_COMM_SELF,pcbddc->local_primal_size,0,1,&local_IS);CHKERRQ(ierr);
     ierr = ISCreateGeneral(PETSC_COMM_SELF,pcbddc->local_primal_size,pcbddc->local_primal_indices,PETSC_COPY_VALUES,&global_IS);CHKERRQ(ierr);
     ierr = VecScatterCreate(pcbddc->vec1_P,local_IS,pcbddc->coarse_vec,global_IS,&pcbddc->coarse_loc_to_glob);CHKERRQ(ierr);
     ierr = ISDestroy(&local_IS);CHKERRQ(ierr);
     ierr = ISDestroy(&global_IS);CHKERRQ(ierr);
  }


  /* Evaluate condition number of coarse problem for cheby (and verbose output if requested) */
  if( pcbddc->coarse_problem_type == MULTILEVEL_BDDC && rank_prec_comm == active_rank ) {
    PetscScalar m_one=-1.0;
    PetscReal   infty_error,lambda_min,lambda_max,kappa_2;
    const KSPType check_ksp_type=KSPGMRES;

    /* change coarse ksp object to an iterative method suitable for extreme eigenvalues' estimation */
    ierr = KSPSetType(pcbddc->coarse_ksp,check_ksp_type);CHKERRQ(ierr);
    ierr = KSPSetComputeSingularValues(pcbddc->coarse_ksp,PETSC_TRUE);CHKERRQ(ierr);
    ierr = KSPSetTolerances(pcbddc->coarse_ksp,1.e-8,1.e-8,PETSC_DEFAULT,pcbddc->coarse_size);CHKERRQ(ierr);
    ierr = KSPSetUp(pcbddc->coarse_ksp);CHKERRQ(ierr);
    ierr = VecSetRandom(pcbddc->coarse_rhs,PETSC_NULL);CHKERRQ(ierr);
    ierr = MatMult(pcbddc->coarse_mat,pcbddc->coarse_rhs,pcbddc->coarse_vec);CHKERRQ(ierr);
    ierr = MatMult(pcbddc->coarse_mat,pcbddc->coarse_vec,pcbddc->coarse_rhs);CHKERRQ(ierr);
    ierr = KSPSolve(pcbddc->coarse_ksp,pcbddc->coarse_rhs,pcbddc->coarse_rhs);CHKERRQ(ierr);
    ierr = KSPComputeExtremeSingularValues(pcbddc->coarse_ksp,&lambda_max,&lambda_min);CHKERRQ(ierr);
    if(dbg_flag) {
      kappa_2=lambda_max/lambda_min;
      ierr = KSPGetIterationNumber(pcbddc->coarse_ksp,&k);CHKERRQ(ierr);
      ierr = VecAXPY(pcbddc->coarse_rhs,m_one,pcbddc->coarse_vec);CHKERRQ(ierr);
      ierr = VecNorm(pcbddc->coarse_rhs,NORM_INFINITY,&infty_error);CHKERRQ(ierr);
      ierr = PetscViewerASCIIPrintf(viewer,"Coarse problem condition number estimated with %d iterations of %s is: % 1.14e\n",k,check_ksp_type,kappa_2);CHKERRQ(ierr);
      ierr = PetscViewerASCIIPrintf(viewer,"Coarse problem eigenvalues: % 1.14e %1.14e\n",lambda_min,lambda_max);CHKERRQ(ierr);
      ierr = PetscViewerASCIIPrintf(viewer,"Coarse problem infty_error: %1.14e\n",infty_error);CHKERRQ(ierr);
    }
    /* restore coarse ksp to default values */
    ierr = KSPSetComputeSingularValues(pcbddc->coarse_ksp,PETSC_FALSE);CHKERRQ(ierr);
    ierr = KSPSetType(pcbddc->coarse_ksp,coarse_ksp_type);CHKERRQ(ierr);
    ierr = KSPChebychevSetEigenvalues(pcbddc->coarse_ksp,lambda_max,lambda_min);CHKERRQ(ierr);
    ierr = KSPSetTolerances(pcbddc->coarse_ksp,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT,max_it_coarse_ksp);CHKERRQ(ierr);
    ierr = KSPSetFromOptions(pcbddc->coarse_ksp);CHKERRQ(ierr);
    ierr = KSPSetUp(pcbddc->coarse_ksp);CHKERRQ(ierr);
  }

  /* free data structures no longer needed */
  if(coarse_ISLG)                { ierr = ISLocalToGlobalMappingDestroy(&coarse_ISLG);CHKERRQ(ierr); }
  if(ins_local_primal_indices)   { ierr = PetscFree(ins_local_primal_indices);CHKERRQ(ierr);  }
  if(ins_coarse_mat_vals)        { ierr = PetscFree(ins_coarse_mat_vals);CHKERRQ(ierr);}
  if(localsizes2)                { ierr = PetscFree(localsizes2);CHKERRQ(ierr);}
  if(localdispl2)                { ierr = PetscFree(localdispl2);CHKERRQ(ierr);}
  if(temp_coarse_mat_vals)       { ierr = PetscFree(temp_coarse_mat_vals);CHKERRQ(ierr);}

  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "PCBDDCManageLocalBoundaries"
static PetscErrorCode PCBDDCManageLocalBoundaries(PC pc)
{

  PC_BDDC     *pcbddc = (PC_BDDC*)pc->data;
  PC_IS         *pcis = (PC_IS*)pc->data;
  Mat_IS      *matis  = (Mat_IS*)pc->pmat->data;
  PCBDDCGraph mat_graph;
  Mat         mat_adj;
  PetscInt    **neighbours_set;
  PetscInt    *queue_in_global_numbering;
  PetscInt    bs,ierr,i,j,s,k,iindex,neumann_bsize,dirichlet_bsize;
  PetscInt    total_counts,nodes_touched=0,where_values=1,vertex_size;
  PetscMPIInt adapt_interface=0,adapt_interface_reduced=0;
  PetscBool   same_set,flg_row;
  PetscBool   symmetrize_rowij=PETSC_TRUE,compressed_rowij=PETSC_FALSE;
  MPI_Comm    interface_comm=((PetscObject)pc)->comm;
  PetscBool   use_faces=PETSC_FALSE,use_edges=PETSC_FALSE;
  const PetscInt *neumann_nodes;
  const PetscInt *dirichlet_nodes;
  IS          used_IS;

  PetscFunctionBegin;
  /* allocate and initialize needed graph structure */
  ierr = PetscMalloc(sizeof(*mat_graph),&mat_graph);CHKERRQ(ierr);
  ierr = MatConvert(matis->A,MATMPIADJ,MAT_INITIAL_MATRIX,&mat_adj);CHKERRQ(ierr);
  /* ierr = MatDuplicate(matis->A,MAT_COPY_VALUES,&mat_adj);CHKERRQ(ierr); */
  ierr = MatGetRowIJ(mat_adj,0,symmetrize_rowij,compressed_rowij,&mat_graph->nvtxs,&mat_graph->xadj,&mat_graph->adjncy,&flg_row);CHKERRQ(ierr);
  if(!flg_row) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Error in MatGetRowIJ called from PCBDDCManageLocalBoundaries.\n");
  i = mat_graph->nvtxs;
  ierr = PetscMalloc4(i,PetscInt,&mat_graph->where,i,PetscInt,&mat_graph->count,i+1,PetscInt,&mat_graph->cptr,i,PetscInt,&mat_graph->queue);CHKERRQ(ierr);
  ierr = PetscMalloc3(i,PetscInt,&mat_graph->which_dof,i,PetscBool,&mat_graph->touched,i,PetscInt,&queue_in_global_numbering);CHKERRQ(ierr);
  ierr = PetscMemzero(mat_graph->where,mat_graph->nvtxs*sizeof(PetscInt));CHKERRQ(ierr);
  ierr = PetscMemzero(mat_graph->count,mat_graph->nvtxs*sizeof(PetscInt));CHKERRQ(ierr);
  ierr = PetscMemzero(mat_graph->which_dof,mat_graph->nvtxs*sizeof(PetscInt));CHKERRQ(ierr);
  ierr = PetscMemzero(mat_graph->queue,mat_graph->nvtxs*sizeof(PetscInt));CHKERRQ(ierr);
  ierr = PetscMemzero(mat_graph->cptr,(mat_graph->nvtxs+1)*sizeof(PetscInt));CHKERRQ(ierr);
  for(i=0;i<mat_graph->nvtxs;i++){mat_graph->touched[i]=PETSC_FALSE;}

  /* Setting dofs splitting in mat_graph->which_dof */
  if(pcbddc->n_ISForDofs) { /* get information about dofs' splitting if provided by the user */
    PetscInt *is_indices;
    PetscInt is_size;
    for(i=0;i<pcbddc->n_ISForDofs;i++) {
      ierr = ISGetSize(pcbddc->ISForDofs[i],&is_size);CHKERRQ(ierr);
      ierr = ISGetIndices(pcbddc->ISForDofs[i],(const PetscInt**)&is_indices);CHKERRQ(ierr);
      for(j=0;j<is_size;j++) {
        mat_graph->which_dof[is_indices[j]]=i;
      }
      ierr = ISRestoreIndices(pcbddc->ISForDofs[i],(const PetscInt**)&is_indices);CHKERRQ(ierr);
    }
    /* use mat block size as vertex size */
    ierr = MatGetBlockSize(matis->A,&vertex_size);CHKERRQ(ierr);
  } else { /* otherwise it assumes a constant block size */
    ierr = MatGetBlockSize(matis->A,&bs);CHKERRQ(ierr);
    for(i=0;i<mat_graph->nvtxs/bs;i++) {
      for(s=0;s<bs;s++) {
        mat_graph->which_dof[i*bs+s]=s;
      }
    }
    vertex_size=1;
  }
  /* count number of neigh per node */
  total_counts=0;
  for(i=1;i<pcis->n_neigh;i++){
    s=pcis->n_shared[i];
    total_counts+=s;
    for(j=0;j<s;j++){
      mat_graph->count[pcis->shared[i][j]] += 1;
    }
  }
  /* Take into account Neumann data -> it increments number of sharing subdomains for all but faces nodes lying on the interface */
  ierr = PCBDDCGetNeumannBoundaries(pc,&used_IS);CHKERRQ(ierr);
  if(used_IS) {
    ierr = ISGetSize(used_IS,&neumann_bsize);CHKERRQ(ierr);
    ierr = ISGetIndices(used_IS,&neumann_nodes);CHKERRQ(ierr);
    for(i=0;i<neumann_bsize;i++){
      iindex = neumann_nodes[i];
      if(mat_graph->count[iindex] > 1){
        mat_graph->count[iindex]+=1;
        total_counts++;
      }
    }
  }
  /* allocate space for storing the set of neighbours of each node */
  ierr = PetscMalloc(mat_graph->nvtxs*sizeof(PetscInt*),&neighbours_set);CHKERRQ(ierr);
  if(mat_graph->nvtxs) { ierr = PetscMalloc(total_counts*sizeof(PetscInt),&neighbours_set[0]);CHKERRQ(ierr); }
  for(i=1;i<mat_graph->nvtxs;i++) neighbours_set[i]=neighbours_set[i-1]+mat_graph->count[i-1];
  ierr = PetscMemzero(mat_graph->count,mat_graph->nvtxs*sizeof(PetscInt));CHKERRQ(ierr);
  for(i=1;i<pcis->n_neigh;i++){
    s=pcis->n_shared[i];
    for(j=0;j<s;j++) {
      k=pcis->shared[i][j];
      neighbours_set[k][mat_graph->count[k]] = pcis->neigh[i];
      mat_graph->count[k]+=1;
    }
  }
  /* set -1 fake neighbour to mimic Neumann boundary */
  if(used_IS) {
    for(i=0;i<neumann_bsize;i++){
      iindex = neumann_nodes[i];
      if(mat_graph->count[iindex] > 1){
        neighbours_set[iindex][mat_graph->count[iindex]] = -1;
        mat_graph->count[iindex]+=1;
      }
    }
    ierr = ISRestoreIndices(used_IS,&neumann_nodes);CHKERRQ(ierr);
  }
  /* sort set of sharing subdomains (needed for comparison below) */
  for(i=0;i<mat_graph->nvtxs;i++) { ierr = PetscSortInt(mat_graph->count[i],neighbours_set[i]);CHKERRQ(ierr); }
  /* remove interior nodes and dirichlet boundary nodes from the next search into the graph */
  ierr = PCBDDCGetDirichletBoundaries(pc,&used_IS);CHKERRQ(ierr);
  if(used_IS) {
    ierr = ISGetSize(used_IS,&dirichlet_bsize);CHKERRQ(ierr);
    ierr = ISGetIndices(used_IS,&dirichlet_nodes);CHKERRQ(ierr);
    for(i=0;i<dirichlet_bsize;i++){
      mat_graph->count[dirichlet_nodes[i]]=0;
    }
    ierr = ISRestoreIndices(used_IS,&dirichlet_nodes);CHKERRQ(ierr);
  }
  for(i=0;i<mat_graph->nvtxs;i++){
    if(!mat_graph->count[i]){  /* interior nodes */
      mat_graph->touched[i]=PETSC_TRUE;
      mat_graph->where[i]=0;
      nodes_touched++;
    }
  }
  mat_graph->ncmps = 0;
  while(nodes_touched<mat_graph->nvtxs) {
    /*  find first untouched node in local ordering */
    i=0;
    while(mat_graph->touched[i]) i++;
    mat_graph->touched[i]=PETSC_TRUE;
    mat_graph->where[i]=where_values;
    nodes_touched++;
    /* now find all other nodes having the same set of sharing subdomains */
    for(j=i+1;j<mat_graph->nvtxs;j++){
      /* check for same number of sharing subdomains and dof number */
      if(mat_graph->count[i]==mat_graph->count[j] && mat_graph->which_dof[i] == mat_graph->which_dof[j] ){
        /* check for same set of sharing subdomains */
        same_set=PETSC_TRUE;
        for(k=0;k<mat_graph->count[j];k++){
          if(neighbours_set[i][k]!=neighbours_set[j][k]) {
            same_set=PETSC_FALSE;
          }
        }
        /* I found a friend of mine */
        if(same_set) {
          mat_graph->where[j]=where_values;
          mat_graph->touched[j]=PETSC_TRUE;
          nodes_touched++;
        }
      }
    }
    where_values++;
  }
  where_values--; if(where_values<0) where_values=0;
  ierr = PetscMalloc(where_values*sizeof(PetscMPIInt),&mat_graph->where_ncmps);CHKERRQ(ierr);
  /* Find connected components defined on the shared interface */
  if(where_values) {
    ierr = PCBDDCFindConnectedComponents(mat_graph, where_values);
    /* For consistency among neughbouring procs, I need to sort (by global ordering) each connected component */
    for(i=0;i<mat_graph->ncmps;i++) {
      ierr = ISLocalToGlobalMappingApply(matis->mapping,mat_graph->cptr[i+1]-mat_graph->cptr[i],&mat_graph->queue[mat_graph->cptr[i]],&queue_in_global_numbering[mat_graph->cptr[i]]);CHKERRQ(ierr);
      ierr = PetscSortIntWithArray(mat_graph->cptr[i+1]-mat_graph->cptr[i],&queue_in_global_numbering[mat_graph->cptr[i]],&mat_graph->queue[mat_graph->cptr[i]]);CHKERRQ(ierr);
    }
  }
  /* check consistency of connected components among neighbouring subdomains -> it adapt them in case it is needed */
  for(i=0;i<where_values;i++) {
    /* We are not sure that two connected components will be the same among subdomains sharing a subset of local interface */
    if(mat_graph->where_ncmps[i]>1) {
      adapt_interface=1;
      break;
    }
  }
  ierr = MPI_Allreduce(&adapt_interface,&adapt_interface_reduced,1,MPIU_INT,MPI_LOR,interface_comm);CHKERRQ(ierr);
  if(where_values && adapt_interface_reduced) {

    printf("Adapting Interface\n");

    PetscInt sum_requests=0,my_rank;
    PetscInt buffer_size,start_of_recv,size_of_recv,start_of_send;
    PetscInt temp_buffer_size,ins_val,global_where_counter;
    PetscInt *cum_recv_counts;
    PetscInt *where_to_nodes_indices;
    PetscInt *petsc_buffer;
    PetscMPIInt *recv_buffer;
    PetscMPIInt *recv_buffer_where;
    PetscMPIInt *send_buffer;
    PetscMPIInt size_of_send;
    PetscInt *sizes_of_sends;
    MPI_Request *send_requests;
    MPI_Request *recv_requests;
    PetscInt *where_cc_adapt;
    PetscInt **temp_buffer;
    PetscInt *nodes_to_temp_buffer_indices;
    PetscInt *add_to_where;

    ierr = MPI_Comm_rank(interface_comm,&my_rank);CHKERRQ(ierr);
    ierr = PetscMalloc((where_values+1)*sizeof(PetscInt),&cum_recv_counts);CHKERRQ(ierr);
    ierr = PetscMemzero(cum_recv_counts,(where_values+1)*sizeof(PetscInt));CHKERRQ(ierr);
    ierr = PetscMalloc(where_values*sizeof(PetscInt),&where_to_nodes_indices);CHKERRQ(ierr);
    /* first count how many neighbours per connected component I will receive from */
    cum_recv_counts[0]=0;
    for(i=1;i<where_values+1;i++){
      j=0;
      while(mat_graph->where[j] != i) j++;
      where_to_nodes_indices[i-1]=j;
      if(neighbours_set[j][0]!=-1) { cum_recv_counts[i]=cum_recv_counts[i-1]+mat_graph->count[j]; } /* We don't want sends/recvs_to/from_self -> here I don't count myself  */
      else { cum_recv_counts[i]=cum_recv_counts[i-1]+mat_graph->count[j]-1; }
    }
    buffer_size=2*cum_recv_counts[where_values]+mat_graph->nvtxs;
    ierr = PetscMalloc(2*cum_recv_counts[where_values]*sizeof(PetscMPIInt),&recv_buffer_where);CHKERRQ(ierr);
    ierr = PetscMalloc(buffer_size*sizeof(PetscMPIInt),&send_buffer);CHKERRQ(ierr);
    ierr = PetscMalloc(cum_recv_counts[where_values]*sizeof(MPI_Request),&send_requests);CHKERRQ(ierr);
    ierr = PetscMalloc(cum_recv_counts[where_values]*sizeof(MPI_Request),&recv_requests);CHKERRQ(ierr);
    for(i=0;i<cum_recv_counts[where_values];i++) {
      send_requests[i]=MPI_REQUEST_NULL;
      recv_requests[i]=MPI_REQUEST_NULL;
    }
    /* exchange with my neighbours the number of my connected components on the shared interface */
    for(i=0;i<where_values;i++){
      j=where_to_nodes_indices[i];
      k = (neighbours_set[j][0] == -1 ?  1 : 0);
      for(;k<mat_graph->count[j];k++){
        ierr = MPI_Isend(&mat_graph->where_ncmps[i],1,MPIU_INT,neighbours_set[j][k],(my_rank+1)*mat_graph->count[j],interface_comm,&send_requests[sum_requests]);CHKERRQ(ierr);
        ierr = MPI_Irecv(&recv_buffer_where[sum_requests],1,MPIU_INT,neighbours_set[j][k],(neighbours_set[j][k]+1)*mat_graph->count[j],interface_comm,&recv_requests[sum_requests]);CHKERRQ(ierr);
        sum_requests++;
      }
    }
    ierr = MPI_Waitall(sum_requests,recv_requests,MPI_STATUSES_IGNORE);CHKERRQ(ierr);
    ierr = MPI_Waitall(sum_requests,send_requests,MPI_STATUSES_IGNORE);CHKERRQ(ierr);
    /* determine the connected component I need to adapt */
    ierr = PetscMalloc(where_values*sizeof(PetscInt),&where_cc_adapt);CHKERRQ(ierr);
    ierr = PetscMemzero(where_cc_adapt,where_values*sizeof(PetscInt));CHKERRQ(ierr);
    for(i=0;i<where_values;i++){
      for(j=cum_recv_counts[i];j<cum_recv_counts[i+1];j++){
        /* The first condition is natural (i.e someone has a different number of cc than me), the second one is just to be safe */
        if( mat_graph->where_ncmps[i]!=recv_buffer_where[j] || mat_graph->where_ncmps[i] > 1 ) {
          where_cc_adapt[i]=PETSC_TRUE;
          break;
        }
      }
    }
    /* now get from neighbours their ccs (in global numbering) and adapt them (in case it is needed) */
    /* first determine how much data to send (size of each queue plus the global indices) and communicate it to neighbours */
    ierr = PetscMalloc(where_values*sizeof(PetscInt),&sizes_of_sends);CHKERRQ(ierr);
    ierr = PetscMemzero(sizes_of_sends,where_values*sizeof(PetscInt));CHKERRQ(ierr);
    sum_requests=0;
    start_of_send=0;
    start_of_recv=cum_recv_counts[where_values];
    for(i=0;i<where_values;i++) {
      if(where_cc_adapt[i]) {
        size_of_send=0;
        for(j=i;j<mat_graph->ncmps;j++) {
          if(mat_graph->where[mat_graph->queue[mat_graph->cptr[j]]] == i+1) { /* WARNING -> where values goes from 1 to where_values included */
            send_buffer[start_of_send+size_of_send]=mat_graph->cptr[j+1]-mat_graph->cptr[j];
            size_of_send+=1;
            for(k=0;k<mat_graph->cptr[j+1]-mat_graph->cptr[j];k++) {
              send_buffer[start_of_send+size_of_send+k]=queue_in_global_numbering[mat_graph->cptr[j]+k];
            }
            size_of_send=size_of_send+mat_graph->cptr[j+1]-mat_graph->cptr[j];
          }
        }
        j = where_to_nodes_indices[i];
        k = (neighbours_set[j][0] == -1 ?  1 : 0);
        for(;k<mat_graph->count[j];k++){
          ierr = MPI_Isend(&size_of_send,1,MPIU_INT,neighbours_set[j][k],(my_rank+1)*mat_graph->count[j],interface_comm,&send_requests[sum_requests]);CHKERRQ(ierr);
          ierr = MPI_Irecv(&recv_buffer_where[sum_requests+start_of_recv],1,MPIU_INT,neighbours_set[j][k],(neighbours_set[j][k]+1)*mat_graph->count[j],interface_comm,&recv_requests[sum_requests]);CHKERRQ(ierr);
          sum_requests++;
        }
        sizes_of_sends[i]=size_of_send;
        start_of_send+=size_of_send;
      }
    }
    ierr = MPI_Waitall(sum_requests,send_requests,MPI_STATUSES_IGNORE);CHKERRQ(ierr);
    ierr = MPI_Waitall(sum_requests,recv_requests,MPI_STATUSES_IGNORE);CHKERRQ(ierr);
    buffer_size=0;
    for(k=0;k<sum_requests;k++) { buffer_size+=recv_buffer_where[start_of_recv+k]; }
    ierr = PetscMalloc(buffer_size*sizeof(PetscMPIInt),&recv_buffer);CHKERRQ(ierr);
    /* now exchange the data */
    start_of_recv=0;
    start_of_send=0;
    sum_requests=0;
    for(i=0;i<where_values;i++) {
      if(where_cc_adapt[i]) {
        size_of_send = sizes_of_sends[i];
        j = where_to_nodes_indices[i];
        k = (neighbours_set[j][0] == -1 ?  1 : 0);
        for(;k<mat_graph->count[j];k++){
          ierr = MPI_Isend(&send_buffer[start_of_send],size_of_send,MPIU_INT,neighbours_set[j][k],(my_rank+1)*mat_graph->count[j],interface_comm,&send_requests[sum_requests]);CHKERRQ(ierr);
          size_of_recv=recv_buffer_where[cum_recv_counts[where_values]+sum_requests];
          ierr = MPI_Irecv(&recv_buffer[start_of_recv],size_of_recv,MPIU_INT,neighbours_set[j][k],(neighbours_set[j][k]+1)*mat_graph->count[j],interface_comm,&recv_requests[sum_requests]);CHKERRQ(ierr);
          start_of_recv+=size_of_recv;
          sum_requests++;
        }
        start_of_send+=size_of_send;
      }
    }
    ierr = MPI_Waitall(sum_requests,recv_requests,MPI_STATUSES_IGNORE);CHKERRQ(ierr);
    ierr = MPI_Waitall(sum_requests,send_requests,MPI_STATUSES_IGNORE);CHKERRQ(ierr);
    ierr = PetscMalloc(buffer_size*sizeof(PetscInt),&petsc_buffer);CHKERRQ(ierr);
    for(k=0;k<start_of_recv;k++) { petsc_buffer[k]=(PetscInt)recv_buffer[k]; }
    for(j=0;j<buffer_size;) {
       ierr = ISGlobalToLocalMappingApply(matis->mapping,IS_GTOLM_MASK,petsc_buffer[j],&petsc_buffer[j+1],&petsc_buffer[j],&petsc_buffer[j+1]);CHKERRQ(ierr);
       k=petsc_buffer[j]+1;
       j+=k;
    }
    sum_requests=cum_recv_counts[where_values];
    start_of_recv=0;
    ierr = PetscMalloc(mat_graph->nvtxs*sizeof(PetscInt),&nodes_to_temp_buffer_indices);CHKERRQ(ierr);
    global_where_counter=0;
    for(i=0;i<where_values;i++){
      if(where_cc_adapt[i]){
        temp_buffer_size=0;
        /* find nodes on the shared interface we need to adapt */
        for(j=0;j<mat_graph->nvtxs;j++){
          if(mat_graph->where[j]==i+1) {
            nodes_to_temp_buffer_indices[j]=temp_buffer_size;
            temp_buffer_size++;
          } else {
            nodes_to_temp_buffer_indices[j]=-1;
          }
        }
        /* allocate some temporary space */
        ierr = PetscMalloc(temp_buffer_size*sizeof(PetscInt*),&temp_buffer);CHKERRQ(ierr);
        ierr = PetscMalloc(temp_buffer_size*(cum_recv_counts[i+1]-cum_recv_counts[i])*sizeof(PetscInt),&temp_buffer[0]);CHKERRQ(ierr);
        ierr = PetscMemzero(temp_buffer[0],temp_buffer_size*(cum_recv_counts[i+1]-cum_recv_counts[i])*sizeof(PetscInt));CHKERRQ(ierr);
        for(j=1;j<temp_buffer_size;j++){
          temp_buffer[j]=temp_buffer[j-1]+cum_recv_counts[i+1]-cum_recv_counts[i];
        }
        /* analyze contributions from neighbouring subdomains for i-th conn comp
           temp buffer structure:
           supposing part of the interface has dimension 5 (global nodes 0,1,2,3,4)
           3 neighs procs with structured connected components:
             neigh 0: [0 1 4], [2 3];  (2 connected components)
             neigh 1: [0 1], [2 3 4];  (2 connected components)
             neigh 2: [0 4], [1], [2 3]; (3 connected components)
           tempbuffer (row-oriented) should be filled as:
             [ 0, 0, 0;
               0, 0, 1;
               1, 1, 2;
               1, 1, 2;
               0, 1, 0; ];
           This way we can simply recover the resulting structure account for possible intersections of ccs among neighs.
           The mat_graph->where array will be modified to reproduce the following 4 connected components [0], [1], [2 3], [4];
                                                                                                                                   */
        for(j=0;j<cum_recv_counts[i+1]-cum_recv_counts[i];j++) {
          ins_val=0;
          size_of_recv=recv_buffer_where[sum_requests];  /* total size of recv from neighs */
          for(buffer_size=0;buffer_size<size_of_recv;) {  /* loop until all data from neighs has been taken into account */
            for(k=1;k<petsc_buffer[buffer_size+start_of_recv]+1;k++) { /* filling properly temp_buffer using data from a single recv */
              temp_buffer[ nodes_to_temp_buffer_indices[ petsc_buffer[ start_of_recv+buffer_size+k ] ] ][j]=ins_val;
            }
            buffer_size+=k;
            ins_val++;
          }
          start_of_recv+=size_of_recv;
          sum_requests++;
        }
        ierr = PetscMalloc(temp_buffer_size*sizeof(PetscInt),&add_to_where);CHKERRQ(ierr);
        ierr = PetscMemzero(add_to_where,temp_buffer_size*sizeof(PetscInt));CHKERRQ(ierr);
        for(j=0;j<temp_buffer_size;j++){
          if(!add_to_where[j]){ /* found a new cc  */
            global_where_counter++;
            add_to_where[j]=global_where_counter;
            for(k=j+1;k<temp_buffer_size;k++){ /* check for other nodes in new cc */
              same_set=PETSC_TRUE;
              for(s=0;s<cum_recv_counts[i+1]-cum_recv_counts[i];s++){
                if(temp_buffer[j][s]!=temp_buffer[k][s]) {
                  same_set=PETSC_FALSE;
                  break;
                }
              }
              if(same_set) add_to_where[k]=global_where_counter;
            }
          }
        }
        /* insert new data in where array */
        temp_buffer_size=0;
        for(j=0;j<mat_graph->nvtxs;j++){
          if(mat_graph->where[j]==i+1) {
            mat_graph->where[j]=where_values+add_to_where[temp_buffer_size];
            temp_buffer_size++;
          }
        }
        ierr = PetscFree(temp_buffer[0]);CHKERRQ(ierr);
        ierr = PetscFree(temp_buffer);CHKERRQ(ierr);
        ierr = PetscFree(add_to_where);CHKERRQ(ierr);
      }
    }
    ierr = PetscFree(nodes_to_temp_buffer_indices);CHKERRQ(ierr);
    ierr = PetscFree(sizes_of_sends);CHKERRQ(ierr);
    ierr = PetscFree(send_requests);CHKERRQ(ierr);
    ierr = PetscFree(recv_requests);CHKERRQ(ierr);
    ierr = PetscFree(petsc_buffer);CHKERRQ(ierr);
    ierr = PetscFree(recv_buffer);CHKERRQ(ierr);
    ierr = PetscFree(recv_buffer_where);CHKERRQ(ierr);
    ierr = PetscFree(send_buffer);CHKERRQ(ierr);
    ierr = PetscFree(cum_recv_counts);CHKERRQ(ierr);
    ierr = PetscFree(where_to_nodes_indices);CHKERRQ(ierr);
    /* We are ready to evaluate consistent connected components on each part of the shared interface */
    if(global_where_counter) {
      for(i=0;i<mat_graph->nvtxs;i++){ mat_graph->touched[i]=PETSC_FALSE; }
      global_where_counter=0;
      for(i=0;i<mat_graph->nvtxs;i++){
        if(mat_graph->where[i] && !mat_graph->touched[i]) {
          global_where_counter++;
          for(j=i+1;j<mat_graph->nvtxs;j++){
            if(!mat_graph->touched[j] && mat_graph->where[j]==mat_graph->where[i]) {
              mat_graph->where[j]=global_where_counter;
              mat_graph->touched[j]=PETSC_TRUE;
            }
          }
          mat_graph->where[i]=global_where_counter;
          mat_graph->touched[i]=PETSC_TRUE;
        }
      }
      where_values=global_where_counter;
    }
    if(global_where_counter) {
      ierr = PetscMemzero(mat_graph->cptr,(mat_graph->nvtxs+1)*sizeof(PetscInt));CHKERRQ(ierr);
      ierr = PetscMemzero(mat_graph->queue,mat_graph->nvtxs*sizeof(PetscInt));CHKERRQ(ierr);
      ierr = PetscFree(mat_graph->where_ncmps);CHKERRQ(ierr);
      ierr = PetscMalloc(where_values*sizeof(PetscMPIInt),&mat_graph->where_ncmps);CHKERRQ(ierr);
      ierr = PCBDDCFindConnectedComponents(mat_graph, where_values);
      for(i=0;i<mat_graph->ncmps;i++) {
        ierr = ISLocalToGlobalMappingApply(matis->mapping,mat_graph->cptr[i+1]-mat_graph->cptr[i],&mat_graph->queue[mat_graph->cptr[i]],&queue_in_global_numbering[mat_graph->cptr[i]]);CHKERRQ(ierr);
        ierr = PetscSortIntWithArray(mat_graph->cptr[i+1]-mat_graph->cptr[i],&queue_in_global_numbering[mat_graph->cptr[i]],&mat_graph->queue[mat_graph->cptr[i]]);CHKERRQ(ierr);
      }
    }
  } /* Finished adapting interface */
  PetscInt nfc=0;
  PetscInt nec=0;
  PetscInt nvc=0;
  PetscBool twodim_flag=PETSC_FALSE;
  for (i=0; i<mat_graph->ncmps; i++) {
    if( mat_graph->cptr[i+1]-mat_graph->cptr[i] > vertex_size ){
      if(mat_graph->count[mat_graph->queue[mat_graph->cptr[i]]]==1){ /* 1 neigh */
        nfc++;
      } else { /* note that nec will be zero in 2d */
        nec++;
      }
    } else {
      nvc+=mat_graph->cptr[i+1]-mat_graph->cptr[i];
    }
  }

  if(!nec) { /* we are in a 2d case -> no faces, only edges */
    nec = nfc;
    nfc = 0;
    twodim_flag = PETSC_TRUE;
  }
  /* allocate IS arrays for faces, edges. Vertices need a single index set.
     Reusing space allocated in mat_graph->where for creating IS objects */
  if(!pcbddc->vertices_flag && !pcbddc->edges_flag) {
    ierr = PetscMalloc(nfc*sizeof(IS),&pcbddc->ISForFaces);CHKERRQ(ierr);
    use_faces=PETSC_TRUE;
  }
  if(!pcbddc->vertices_flag && !pcbddc->faces_flag) {
    ierr = PetscMalloc(nec*sizeof(IS),&pcbddc->ISForEdges);CHKERRQ(ierr);
    use_edges=PETSC_TRUE;
  }
  nfc=0;
  nec=0;
  for (i=0; i<mat_graph->ncmps; i++) {
    if( mat_graph->cptr[i+1]-mat_graph->cptr[i] > vertex_size ){
      for(j=0;j<mat_graph->cptr[i+1]-mat_graph->cptr[i];j++) {
        mat_graph->where[j]=mat_graph->queue[mat_graph->cptr[i]+j];
      }
      if(mat_graph->count[mat_graph->queue[mat_graph->cptr[i]]]==1){
        if(twodim_flag) {
          if(use_edges) {
            ierr = ISCreateGeneral(PETSC_COMM_SELF,j,mat_graph->where,PETSC_COPY_VALUES,&pcbddc->ISForEdges[nec]);CHKERRQ(ierr);
            nec++;
          }
        } else {
          if(use_faces) {
            ierr = ISCreateGeneral(PETSC_COMM_SELF,j,mat_graph->where,PETSC_COPY_VALUES,&pcbddc->ISForFaces[nfc]);CHKERRQ(ierr);
            nfc++;
          }
        }
      } else {
        if(use_edges) {
          ierr = ISCreateGeneral(PETSC_COMM_SELF,j,mat_graph->where,PETSC_COPY_VALUES,&pcbddc->ISForEdges[nec]);CHKERRQ(ierr);
          nec++;
        }
      }
    }
  }
  pcbddc->n_ISForFaces=nfc;
  pcbddc->n_ISForEdges=nec;
  nvc=0;
  if( !pcbddc->constraints_flag ) {
    for (i=0; i<mat_graph->ncmps; i++) {
      if( mat_graph->cptr[i+1]-mat_graph->cptr[i] <= vertex_size ){
        for( j=mat_graph->cptr[i];j<mat_graph->cptr[i+1];j++) {
          mat_graph->where[nvc]=mat_graph->queue[j];
          nvc++;
        }
      }
    }
  }
  /* sort vertex set (by local ordering) */
  ierr = PetscSortInt(nvc,mat_graph->where);CHKERRQ(ierr);
  ierr = ISCreateGeneral(PETSC_COMM_SELF,nvc,mat_graph->where,PETSC_COPY_VALUES,&pcbddc->ISForVertices);CHKERRQ(ierr);

  if(pcbddc->dbg_flag) {
    PetscViewer viewer=pcbddc->dbg_viewer;

    ierr = PetscViewerASCIISynchronizedPrintf(viewer,"--------------------------------------------------------------\n");CHKERRQ(ierr);
    ierr = PetscViewerASCIISynchronizedPrintf(viewer,"Details from PCBDDCManageLocalBoundaries for subdomain %04d\n",PetscGlobalRank);CHKERRQ(ierr);
    ierr = PetscViewerASCIISynchronizedPrintf(viewer,"--------------------------------------------------------------\n");CHKERRQ(ierr);
/*    ierr = PetscViewerASCIISynchronizedPrintf(viewer,"Graph (adjacency structure) of local Neumann mat\n");CHKERRQ(ierr);
    ierr = PetscViewerASCIISynchronizedPrintf(viewer,"--------------------------------------------------------------\n");CHKERRQ(ierr);
    for(i=0;i<mat_graph->nvtxs;i++) {
      ierr = PetscViewerASCIISynchronizedPrintf(viewer,"Nodes connected to node number %d are %d\n",i,mat_graph->xadj[i+1]-mat_graph->xadj[i]);CHKERRQ(ierr);
      for(j=mat_graph->xadj[i];j<mat_graph->xadj[i+1];j++){
        ierr = PetscViewerASCIISynchronizedPrintf(viewer,"%d ",mat_graph->adjncy[j]);CHKERRQ(ierr);
      }
      ierr = PetscViewerASCIISynchronizedPrintf(viewer,"\n--------------------------------------------------------------\n");CHKERRQ(ierr);
    }
    ierr = PetscViewerASCIISynchronizedPrintf(viewer,"Matrix graph has %d connected components", mat_graph->ncmps);CHKERRQ(ierr);
    for(i=0;i<mat_graph->ncmps;i++) {
      ierr = PetscViewerASCIISynchronizedPrintf(viewer,"\nDetails for connected component number %02d: size %04d, count %01d. Nodes follow.\n",
             i,mat_graph->cptr[i+1]-mat_graph->cptr[i],mat_graph->count[mat_graph->queue[mat_graph->cptr[i]]]);CHKERRQ(ierr);
      for (j=mat_graph->cptr[i]; j<mat_graph->cptr[i+1]; j++){
        ierr = PetscViewerASCIISynchronizedPrintf(viewer,"%d (%d), ",queue_in_global_numbering[j],mat_graph->queue[j]);CHKERRQ(ierr);
      }
    }
    ierr = PetscViewerASCIISynchronizedPrintf(viewer,"\n--------------------------------------------------------------\n");CHKERRQ(ierr);*/
    ierr = PetscViewerASCIISynchronizedPrintf(viewer,"Subdomain %04d detected %02d local vertices\n",PetscGlobalRank,nvc);CHKERRQ(ierr);
    ierr = PetscViewerASCIISynchronizedPrintf(viewer,"Subdomain %04d detected %02d local faces\n",PetscGlobalRank,nfc);CHKERRQ(ierr);
    ierr = PetscViewerASCIISynchronizedPrintf(viewer,"Subdomain %04d detected %02d local edges\n",PetscGlobalRank,nec);CHKERRQ(ierr);
    ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
  }

  /* Restore CSR structure into sequantial matrix and free memory space no longer needed */
  ierr = MatRestoreRowIJ(mat_adj,0,symmetrize_rowij,compressed_rowij,&mat_graph->nvtxs,&mat_graph->xadj,&mat_graph->adjncy,&flg_row);CHKERRQ(ierr);
  if(!flg_row) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Error in MatRestoreRowIJ called from PCBDDCManageLocalBoundaries.\n");
  ierr = MatDestroy(&mat_adj);CHKERRQ(ierr);
  /* Free graph structure */
  if(mat_graph->nvtxs){
    ierr = PetscFree(neighbours_set[0]);CHKERRQ(ierr);
    ierr = PetscFree(neighbours_set);CHKERRQ(ierr);
    ierr = PetscFree4(mat_graph->where,mat_graph->count,mat_graph->cptr,mat_graph->queue);CHKERRQ(ierr);
    ierr = PetscFree3(mat_graph->which_dof,mat_graph->touched,queue_in_global_numbering);CHKERRQ(ierr);
    ierr = PetscFree(mat_graph->where_ncmps);CHKERRQ(ierr);
  }
  ierr = PetscFree(mat_graph);CHKERRQ(ierr);

  PetscFunctionReturn(0);

}

/* -------------------------------------------------------------------------- */

/* The following code has been adapted from function IsConnectedSubdomain contained
   in source file contig.c of METIS library (version 5.0.1)                           */

#undef __FUNCT__
#define __FUNCT__ "PCBDDCFindConnectedComponents"
static PetscErrorCode PCBDDCFindConnectedComponents(PCBDDCGraph graph, PetscInt n_dist )
{
  PetscInt i, j, k, nvtxs, first, last, nleft, ncmps,pid,cum_queue,n,ncmps_pid;
  PetscInt *xadj, *adjncy, *where, *queue;
  PetscInt *cptr;
  PetscBool *touched;

  PetscFunctionBegin;

  nvtxs   = graph->nvtxs;
  xadj    = graph->xadj;
  adjncy  = graph->adjncy;
  where   = graph->where;
  touched = graph->touched;
  queue   = graph->queue;
  cptr    = graph->cptr;

  for (i=0; i<nvtxs; i++)
    touched[i] = PETSC_FALSE;

  cum_queue=0;
  ncmps=0;

  for(n=0; n<n_dist; n++) {
    pid = n+1;
    nleft = 0;
    for (i=0; i<nvtxs; i++) {
      if (where[i] == pid)
        nleft++;
    }
    for (i=0; i<nvtxs; i++) {
      if (where[i] == pid)
        break;
    }
    touched[i] = PETSC_TRUE;
    queue[cum_queue] = i;
    first = 0; last = 1;
    cptr[ncmps] = cum_queue;  /* This actually points to queue */
    ncmps_pid = 0;
    while (first != nleft) {
      if (first == last) { /* Find another starting vertex */
        cptr[++ncmps] = first+cum_queue;
        ncmps_pid++;
        for (i=0; i<nvtxs; i++) {
          if (where[i] == pid && !touched[i])
            break;
        }
        queue[cum_queue+last] = i;
        last++;
        touched[i] = PETSC_TRUE;
      }
      i = queue[cum_queue+first];
      first++;
      for (j=xadj[i]; j<xadj[i+1]; j++) {
        k = adjncy[j];
        if (where[k] == pid && !touched[k]) {
          queue[cum_queue+last] = k;
          last++;
          touched[k] = PETSC_TRUE;
        }
      }
    }
    cptr[++ncmps] = first+cum_queue;
    ncmps_pid++;
    cum_queue=cptr[ncmps];
    graph->where_ncmps[n] = ncmps_pid;
  }
  graph->ncmps = ncmps;

  PetscFunctionReturn(0);
}