xref: /petsc/src/dm/impls/composite/pack.c (revision 6eb61c8c1b9068eedbdbf3fc6ee8b16d6280ad80)

#define PETSCDM_DLL

#include "petscdm.h"             /*I      "petscdm.h"     I*/
#include "private/dmimpl.h"
#include "petscmat.h"

/*
   rstart is where an array/subvector starts in the global parallel vector, so arrays
   rstarts are meaningless (and set to the previous one) except on the processor where the array lives
*/

typedef enum {DMCOMPOSITE_ARRAY, DMCOMPOSITE_DM} DMCompositeLinkType;

struct DMCompositeLink {
  DMCompositeLinkType    type;
  struct DMCompositeLink *next;
  PetscInt               n,rstart;      /* rstart is relative to this process */
  PetscInt               grstart;       /* grstart is relative to all processes */

  /* only used for DMCOMPOSITE_DM */
  PetscInt               *grstarts;     /* global row for first unknown of this DM on each process */
  DM                     dm;

  /* only used for DMCOMPOSITE_ARRAY */
  PetscMPIInt            rank;          /* process where array unknowns live */
};

typedef struct {
  PetscInt               n,N,rstart;           /* rstart is relative to all processors, n unknowns owned by this process, N is total unknowns */
  PetscInt               nghost;               /* number of all local entries include DMDA ghost points and any shared redundant arrays */
  PetscInt               nDM,nredundant,nmine; /* how many DM's and seperate redundant arrays used to build DM(nmine is ones on this process) */
  PetscBool              setup;                /* after this is set, cannot add new links to the DM*/
  struct DMCompositeLink *next;

  PetscErrorCode (*FormCoupleLocations)(DM,Mat,PetscInt*,PetscInt*,PetscInt,PetscInt,PetscInt,PetscInt);
} DM_Composite;

#undef __FUNCT__
#define __FUNCT__ "DMCompositeSetCoupling"
/*@C
    DMCompositeSetCoupling - Sets user provided routines that compute the coupling between the
      seperate components (DMDA's and arrays) in a DMto build the correct matrix nonzero structure.


    Logically Collective on MPI_Comm

    Input Parameter:
+   dm - the composite object
-   formcouplelocations - routine to set the nonzero locations in the matrix

    Level: advanced

    Notes: See DMCompositeSetContext() and DMCompositeGetContext() for how to get user information into
        this routine

@*/
PetscErrorCode PETSCDM_DLLEXPORT DMCompositeSetCoupling(DM dm,PetscErrorCode (*FormCoupleLocations)(DM,Mat,PetscInt*,PetscInt*,PetscInt,PetscInt,PetscInt,PetscInt))
{
  DM_Composite *com = (DM_Composite*)dm->data;

  PetscFunctionBegin;
  com->FormCoupleLocations = FormCoupleLocations;
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeSetContext"
/*@
    DMCompositeSetContext - Allows user to stash data they may need within the form coupling routine they
      set with DMCompositeSetCoupling()


    Not Collective

    Input Parameter:
+   dm - the composite object
-   ctx - the user supplied context

    Level: advanced

    Notes: Use DMCompositeGetContext() to retrieve the context when needed.

@*/
PetscErrorCode PETSCDM_DLLEXPORT DMCompositeSetContext(DM dm,void *ctx)
{
  PetscFunctionBegin;
  dm->ctx = ctx;
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeGetContext"
/*@
    DMCompositeGetContext - Access the context set with DMCompositeSetContext()


    Not Collective

    Input Parameter:
.   dm - the composite object

    Output Parameter:
.    ctx - the user supplied context

    Level: advanced

    Notes: Use DMCompositeGetContext() to retrieve the context when needed.

@*/
PetscErrorCode PETSCDM_DLLEXPORT DMCompositeGetContext(DM dm,void **ctx)
{
  PetscFunctionBegin;
  *ctx = dm->ctx;
  PetscFunctionReturn(0);
}



extern PetscErrorCode DMDestroy_Private(DM,PetscBool *);

#undef __FUNCT__
#define __FUNCT__ "DMDestroy_Composite"
PetscErrorCode PETSCDM_DLLEXPORT DMDestroy_Composite(DM dm)
{
  PetscErrorCode         ierr;
  struct DMCompositeLink *next, *prev;
  PetscBool              done;
  DM_Composite           *com = (DM_Composite *)dm->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm,DM_CLASSID,1);
  ierr = DMDestroy_Private((DM)dm,&done);CHKERRQ(ierr);
  if (!done) PetscFunctionReturn(0);

  next = com->next;
  while (next) {
    prev = next;
    next = next->next;
    if (prev->type == DMCOMPOSITE_DM) {
      ierr = DMDestroy(prev->dm);CHKERRQ(ierr);
    }
    if (prev->grstarts) {
      ierr = PetscFree(prev->grstarts);CHKERRQ(ierr);
    }
    ierr = PetscFree(prev);CHKERRQ(ierr);
  }
  ierr = PetscFree(com);CHKERRQ(ierr);
  ierr = PetscHeaderDestroy(dm);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMView_Composite"
PetscErrorCode PETSCDM_DLLEXPORT DMView_Composite(DM dm,PetscViewer v)
{
  PetscErrorCode ierr;
  PetscBool      iascii;
  DM_Composite   *com = (DM_Composite *)dm->data;

  PetscFunctionBegin;
  ierr = PetscTypeCompare((PetscObject)v,PETSCVIEWERASCII,&iascii);CHKERRQ(ierr);
  if (iascii) {
    struct DMCompositeLink *lnk = com->next;
    PetscInt               i;

    ierr = PetscViewerASCIIPrintf(v,"DM (%s)\n",((PetscObject)dm)->prefix?((PetscObject)dm)->prefix:"no prefix");CHKERRQ(ierr);
    ierr = PetscViewerASCIIPrintf(v,"  contains %d DMs and %d redundant arrays\n",com->nDM,com->nredundant);CHKERRQ(ierr);
    ierr = PetscViewerASCIIPushTab(v);CHKERRQ(ierr);
    for (i=0; lnk; lnk=lnk->next,i++) {
      if (lnk->dm) {
        ierr = PetscViewerASCIIPrintf(v,"Link %d: DM of type %s\n",i,((PetscObject)lnk->dm)->type_name);CHKERRQ(ierr);
        ierr = PetscViewerASCIIPushTab(v);CHKERRQ(ierr);
        ierr = DMView(lnk->dm,v);CHKERRQ(ierr);
        ierr = PetscViewerASCIIPopTab(v);CHKERRQ(ierr);
      } else {
        ierr = PetscViewerASCIIPrintf(v,"Link %d: Redundant array of size %d owned by rank %d\n",i,lnk->n,lnk->rank);CHKERRQ(ierr);
      }
    }
    ierr = PetscViewerASCIIPopTab(v);CHKERRQ(ierr);
  }
  PetscFunctionReturn(0);
}

/* --------------------------------------------------------------------------------------*/
#undef __FUNCT__
#define __FUNCT__ "DMSetUp_Composite"
PetscErrorCode PETSCDM_DLLEXPORT DMSetUp_Composite(DM dm)
{
  PetscErrorCode         ierr;
  PetscInt               nprev = 0;
  PetscMPIInt            rank,size;
  DM_Composite           *com = (DM_Composite*)dm->data;
  struct DMCompositeLink *next = com->next;
  PetscLayout            map;

  PetscFunctionBegin;
  if (com->setup) SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_ARG_WRONGSTATE,"Packer has already been setup");
  ierr = PetscLayoutCreate(((PetscObject)dm)->comm,&map);CHKERRQ(ierr);
  ierr = PetscLayoutSetLocalSize(map,com->n);CHKERRQ(ierr);
  ierr = PetscLayoutSetSize(map,PETSC_DETERMINE);CHKERRQ(ierr);
  ierr = PetscLayoutSetBlockSize(map,1);CHKERRQ(ierr);
  ierr = PetscLayoutSetUp(map);CHKERRQ(ierr);
  ierr = PetscLayoutGetSize(map,&com->N);CHKERRQ(ierr);
  ierr = PetscLayoutGetRange(map,&com->rstart,PETSC_NULL);CHKERRQ(ierr);
  ierr = PetscLayoutDestroy(map);CHKERRQ(ierr);

  /* now set the rstart for each linked array/vector */
  ierr = MPI_Comm_rank(((PetscObject)dm)->comm,&rank);CHKERRQ(ierr);
  ierr = MPI_Comm_size(((PetscObject)dm)->comm,&size);CHKERRQ(ierr);
  while (next) {
    next->rstart = nprev;
    if ((rank == next->rank) || next->type != DMCOMPOSITE_ARRAY) nprev += next->n;
    next->grstart = com->rstart + next->rstart;
    if (next->type == DMCOMPOSITE_ARRAY) {
      ierr = MPI_Bcast(&next->grstart,1,MPIU_INT,next->rank,((PetscObject)dm)->comm);CHKERRQ(ierr);
    } else {
      ierr = PetscMalloc(size*sizeof(PetscInt),&next->grstarts);CHKERRQ(ierr);
      ierr = MPI_Allgather(&next->grstart,1,MPIU_INT,next->grstarts,1,MPIU_INT,((PetscObject)dm)->comm);CHKERRQ(ierr);
    }
    next = next->next;
  }
  com->setup = PETSC_TRUE;
  PetscFunctionReturn(0);
}


#undef __FUNCT__
#define __FUNCT__ "DMCompositeGetAccess_Array"
PetscErrorCode DMCompositeGetAccess_Array(DM dm,struct DMCompositeLink *mine,Vec vec,PetscScalar **array)
{
  PetscErrorCode ierr;
  PetscScalar    *varray;
  PetscMPIInt    rank;

  PetscFunctionBegin;
  ierr = MPI_Comm_rank(((PetscObject)dm)->comm,&rank);CHKERRQ(ierr);
  if (array) {
    if (rank == mine->rank) {
      ierr    = VecGetArray(vec,&varray);CHKERRQ(ierr);
      *array  = varray + mine->rstart;
      ierr    = VecRestoreArray(vec,&varray);CHKERRQ(ierr);
    } else {
      *array = 0;
    }
  }
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeGetAccess_DM"
PetscErrorCode DMCompositeGetAccess_DM(DM dm,struct DMCompositeLink *mine,Vec vec,Vec *global)
{
  PetscErrorCode ierr;
  PetscScalar    *array;

  PetscFunctionBegin;
  if (global) {
    ierr    = DMGetGlobalVector(mine->dm,global);CHKERRQ(ierr);
    ierr    = VecGetArray(vec,&array);CHKERRQ(ierr);
    ierr    = VecPlaceArray(*global,array+mine->rstart);CHKERRQ(ierr);
    ierr    = VecRestoreArray(vec,&array);CHKERRQ(ierr);
  }
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeRestoreAccess_Array"
PetscErrorCode DMCompositeRestoreAccess_Array(DM dm,struct DMCompositeLink *mine,Vec vec,PetscScalar **array)
{
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeRestoreAccess_DM"
PetscErrorCode DMCompositeRestoreAccess_DM(DM dm,struct DMCompositeLink *mine,Vec vec,Vec *global)
{
  PetscErrorCode ierr;

  PetscFunctionBegin;
  if (global) {
    ierr = VecResetArray(*global);CHKERRQ(ierr);
    ierr = DMRestoreGlobalVector(mine->dm,global);CHKERRQ(ierr);
  }
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeScatter_Array"
PetscErrorCode DMCompositeScatter_Array(DM dm,struct DMCompositeLink *mine,Vec vec,PetscScalar *array)
{
  PetscErrorCode ierr;
  PetscScalar    *varray;
  PetscMPIInt    rank;

  PetscFunctionBegin;
  ierr = MPI_Comm_rank(((PetscObject)dm)->comm,&rank);CHKERRQ(ierr);
  if (rank == mine->rank) {
    ierr    = VecGetArray(vec,&varray);CHKERRQ(ierr);
    ierr    = PetscMemcpy(array,varray+mine->rstart,mine->n*sizeof(PetscScalar));CHKERRQ(ierr);
    ierr    = VecRestoreArray(vec,&varray);CHKERRQ(ierr);
  }
  ierr    = MPI_Bcast(array,mine->n,MPIU_SCALAR,mine->rank,((PetscObject)dm)->comm);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeScatter_DM"
PetscErrorCode DMCompositeScatter_DM(DM dm,struct DMCompositeLink *mine,Vec vec,Vec local)
{
  PetscErrorCode ierr;
  PetscScalar    *array;
  Vec            global;

  PetscFunctionBegin;
  ierr = DMGetGlobalVector(mine->dm,&global);CHKERRQ(ierr);
  ierr = VecGetArray(vec,&array);CHKERRQ(ierr);
  ierr = VecPlaceArray(global,array+mine->rstart);CHKERRQ(ierr);
  ierr = DMGlobalToLocalBegin(mine->dm,global,INSERT_VALUES,local);CHKERRQ(ierr);
  ierr = DMGlobalToLocalEnd(mine->dm,global,INSERT_VALUES,local);CHKERRQ(ierr);
  ierr = VecRestoreArray(vec,&array);CHKERRQ(ierr);
  ierr = VecResetArray(global);CHKERRQ(ierr);
  ierr = DMRestoreGlobalVector(mine->dm,&global);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeGather_Array"
PetscErrorCode DMCompositeGather_Array(DM dm,struct DMCompositeLink *mine,Vec vec,InsertMode imode,PetscScalar *array)
{
  PetscErrorCode ierr;
  PetscScalar    *varray;
  PetscMPIInt    rank;

  PetscFunctionBegin;
  ierr = MPI_Comm_rank(((PetscObject)dm)->comm,&rank);CHKERRQ(ierr);
  if (rank == mine->rank) {
    ierr    = VecGetArray(vec,&varray);CHKERRQ(ierr);
    if (varray+mine->rstart == array) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"You need not DMCompositeGather() into objects obtained via DMCompositeGetAccess()");
    switch (imode) {
    case INSERT_VALUES:
      ierr = PetscMemcpy(varray+mine->rstart,array,mine->n*sizeof(PetscScalar));CHKERRQ(ierr);
      break;
    case ADD_VALUES: {
      PetscInt i;
      for (i=0; i<mine->n; i++) varray[mine->rstart+i] += array[i];
    } break;
    default: SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_SUP,"imode");
    }
    ierr    = VecRestoreArray(vec,&varray);CHKERRQ(ierr);
  }
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeGather_DM"
PetscErrorCode DMCompositeGather_DM(DM dm,struct DMCompositeLink *mine,Vec vec,InsertMode imode,Vec local)
{
  PetscErrorCode ierr;
  PetscScalar    *array;
  Vec            global;

  PetscFunctionBegin;
  ierr = DMGetGlobalVector(mine->dm,&global);CHKERRQ(ierr);
  ierr = VecGetArray(vec,&array);CHKERRQ(ierr);
  ierr = VecPlaceArray(global,array+mine->rstart);CHKERRQ(ierr);
  ierr = DMLocalToGlobalBegin(mine->dm,local,imode,global);CHKERRQ(ierr);
  ierr = DMLocalToGlobalEnd(mine->dm,local,imode,global);CHKERRQ(ierr);
  ierr = VecRestoreArray(vec,&array);CHKERRQ(ierr);
  ierr = VecResetArray(global);CHKERRQ(ierr);
  ierr = DMRestoreGlobalVector(mine->dm,&global);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

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

#include <stdarg.h>

#undef __FUNCT__
#define __FUNCT__ "DMCompositeGetNumberDM"
/*@C
    DMCompositeGetNumberDM - Get's the number of DM objects in the DMComposite
       representation.

    Not Collective

    Input Parameter:
.    dm - the packer object

    Output Parameter:
.     nDM - the number of DMs

    Level: beginner

@*/
PetscErrorCode PETSCDM_DLLEXPORT DMCompositeGetNumberDM(DM dm,PetscInt *nDM)
{
  DM_Composite *com = (DM_Composite*)dm->data;
  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm,DM_CLASSID,1);
  *nDM = com->nDM;
  PetscFunctionReturn(0);
}


#undef __FUNCT__
#define __FUNCT__ "DMCompositeGetAccess"
/*@C
    DMCompositeGetAccess - Allows one to access the individual packed vectors in their global
       representation.

    Collective on DMComposite

    Input Parameter:
+    dm - the packer object
.    gvec - the global vector
-    ... - the individual sequential or parallel objects (arrays or vectors)

    Notes: Use DMCompositeRestoreAccess() to return the vectors when you no longer need them

    Level: advanced

@*/
PetscErrorCode PETSCDM_DLLEXPORT DMCompositeGetAccess(DM dm,Vec gvec,...)
{
  va_list                Argp;
  PetscErrorCode         ierr;
  struct DMCompositeLink *next;
  DM_Composite           *com = (DM_Composite*)dm->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm,DM_CLASSID,1);
  PetscValidHeaderSpecific(gvec,VEC_CLASSID,2);
  next = com->next;
  if (!com->setup) {
    ierr = DMSetUp(dm);CHKERRQ(ierr);
  }

  /* loop over packed objects, handling one at at time */
  va_start(Argp,gvec);
  while (next) {
    if (next->type == DMCOMPOSITE_ARRAY) {
      PetscScalar **array;
      array = va_arg(Argp, PetscScalar**);
      ierr  = DMCompositeGetAccess_Array(dm,next,gvec,array);CHKERRQ(ierr);
    } else if (next->type == DMCOMPOSITE_DM) {
      Vec *vec;
      vec  = va_arg(Argp, Vec*);
      ierr = DMCompositeGetAccess_DM(dm,next,gvec,vec);CHKERRQ(ierr);
    } else {
      SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_SUP,"Cannot handle that object type yet");
    }
    next = next->next;
  }
  va_end(Argp);
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeRestoreAccess"
/*@C
    DMCompositeRestoreAccess - Returns the vectors obtained with DMCompositeGetAccess()
       representation.

    Collective on DMComposite

    Input Parameter:
+    dm - the packer object
.    gvec - the global vector
-    ... - the individual sequential or parallel objects (arrays or vectors)

    Level: advanced

.seealso  DMCompositeAddArray(), DMCompositeAddDM(), DMCreateGlobalVector(),
         DMCompositeGather(), DMCompositeCreate(), DMCompositeGetISLocalToGlobalMappings(), DMCompositeScatter(),
         DMCompositeRestoreAccess(), DMCompositeGetAccess()

@*/
PetscErrorCode PETSCDM_DLLEXPORT DMCompositeRestoreAccess(DM dm,Vec gvec,...)
{
  va_list                Argp;
  PetscErrorCode         ierr;
  struct DMCompositeLink *next;
  DM_Composite           *com = (DM_Composite*)dm->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm,DM_CLASSID,1);
  PetscValidHeaderSpecific(gvec,VEC_CLASSID,2);
  next = com->next;
  if (!com->setup) {
    ierr = DMSetUp(dm);CHKERRQ(ierr);
  }

  /* loop over packed objects, handling one at at time */
  va_start(Argp,gvec);
  while (next) {
    if (next->type == DMCOMPOSITE_ARRAY) {
      PetscScalar **array;
      array = va_arg(Argp, PetscScalar**);
      ierr  = DMCompositeRestoreAccess_Array(dm,next,gvec,array);CHKERRQ(ierr);
    } else if (next->type == DMCOMPOSITE_DM) {
      Vec *vec;
      vec  = va_arg(Argp, Vec*);
      ierr = DMCompositeRestoreAccess_DM(dm,next,gvec,vec);CHKERRQ(ierr);
    } else {
      SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_SUP,"Cannot handle that object type yet");
    }
    next = next->next;
  }
  va_end(Argp);
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeScatter"
/*@C
    DMCompositeScatter - Scatters from a global packed vector into its individual local vectors

    Collective on DMComposite

    Input Parameter:
+    dm - the packer object
.    gvec - the global vector
-    ... - the individual sequential objects (arrays or vectors)

    Level: advanced

.seealso DMDestroy(), DMCompositeAddArray(), DMCompositeAddDM(), DMCreateGlobalVector(),
         DMCompositeGather(), DMCompositeCreate(), DMCompositeGetISLocalToGlobalMappings(), DMCompositeGetAccess(),
         DMCompositeGetLocalVectors(), DMCompositeRestoreLocalVectors(), DMCompositeGetEntries()

@*/
PetscErrorCode PETSCDM_DLLEXPORT DMCompositeScatter(DM dm,Vec gvec,...)
{
  va_list                Argp;
  PetscErrorCode         ierr;
  struct DMCompositeLink *next;
  PetscInt               cnt = 3;
  DM_Composite           *com = (DM_Composite*)dm->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm,DM_CLASSID,1);
  PetscValidHeaderSpecific(gvec,VEC_CLASSID,2);
  next = com->next;
  if (!com->setup) {
    ierr = DMSetUp(dm);CHKERRQ(ierr);
  }

  /* loop over packed objects, handling one at at time */
  va_start(Argp,gvec);
  while (next) {
    if (next->type == DMCOMPOSITE_ARRAY) {
      PetscScalar *array;
      array = va_arg(Argp, PetscScalar*);
      ierr = DMCompositeScatter_Array(dm,next,gvec,array);CHKERRQ(ierr);
    } else if (next->type == DMCOMPOSITE_DM) {
      Vec vec;
      vec = va_arg(Argp, Vec);
      PetscValidHeaderSpecific(vec,VEC_CLASSID,cnt);
      ierr = DMCompositeScatter_DM(dm,next,gvec,vec);CHKERRQ(ierr);
    } else {
      SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_SUP,"Cannot handle that object type yet");
    }
    cnt++;
    next = next->next;
  }
  va_end(Argp);
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeGather"
/*@C
    DMCompositeGather - Gathers into a global packed vector from its individual local vectors

    Collective on DMComposite

    Input Parameter:
+    dm - the packer object
.    gvec - the global vector
-    ... - the individual sequential objects (arrays or vectors)

    Level: advanced

.seealso DMDestroy(), DMCompositeAddArray(), DMCompositeAddDM(), DMCreateGlobalVector(),
         DMCompositeScatter(), DMCompositeCreate(), DMCompositeGetISLocalToGlobalMappings(), DMCompositeGetAccess(),
         DMCompositeGetLocalVectors(), DMCompositeRestoreLocalVectors(), DMCompositeGetEntries()

@*/
PetscErrorCode PETSCDM_DLLEXPORT DMCompositeGather(DM dm,Vec gvec,InsertMode imode,...)
{
  va_list                Argp;
  PetscErrorCode         ierr;
  struct DMCompositeLink *next;
  DM_Composite           *com = (DM_Composite*)dm->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm,DM_CLASSID,1);
  PetscValidHeaderSpecific(gvec,VEC_CLASSID,2);
  next = com->next;
  if (!com->setup) {
    ierr = DMSetUp(dm);CHKERRQ(ierr);
  }

  /* loop over packed objects, handling one at at time */
  va_start(Argp,imode);
  while (next) {
    if (next->type == DMCOMPOSITE_ARRAY) {
      PetscScalar *array;
      array = va_arg(Argp, PetscScalar*);
      ierr  = DMCompositeGather_Array(dm,next,gvec,imode,array);CHKERRQ(ierr);
    } else if (next->type == DMCOMPOSITE_DM) {
      Vec vec;
      vec = va_arg(Argp, Vec);
      PetscValidHeaderSpecific(vec,VEC_CLASSID,3);
      ierr = DMCompositeGather_DM(dm,next,gvec,imode,vec);CHKERRQ(ierr);
    } else {
      SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_SUP,"Cannot handle that object type yet");
    }
    next = next->next;
  }
  va_end(Argp);
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeAddArray"
/*@C
    DMCompositeAddArray - adds an "redundant" array to a DMComposite. The array values will
       be stored in part of the array on process orank.

    Collective on DMComposite

    Input Parameter:
+    dm - the packer object
.    orank - the process on which the array entries officially live, this number must be
             the same on all processes.
-    n - the length of the array

    Level: advanced

.seealso DMDestroy(), DMCompositeGather(), DMCompositeAddDM(), DMCreateGlobalVector(),
         DMCompositeScatter(), DMCompositeCreate(), DMCompositeGetISLocalToGlobalMappings(), DMCompositeGetAccess(),
         DMCompositeGetLocalVectors(), DMCompositeRestoreLocalVectors(), DMCompositeGetEntries()

@*/
PetscErrorCode PETSCDM_DLLEXPORT DMCompositeAddArray(DM dm,PetscMPIInt orank,PetscInt n)
{
  struct DMCompositeLink *mine,*next;
  PetscErrorCode         ierr;
  PetscMPIInt            rank;
  DM_Composite           *com = (DM_Composite*)dm->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm,DM_CLASSID,1);
  next = com->next;
  if (com->setup) {
    SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_ARG_WRONGSTATE,"Cannot add an array once you have used the DMComposite");
  }
#if defined(PETSC_USE_DEBUG)
  {
    PetscMPIInt orankmax;
    ierr = MPI_Allreduce(&orank,&orankmax,1,MPI_INT,MPI_MAX,((PetscObject)dm)->comm);CHKERRQ(ierr);
    if (orank != orankmax) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_INCOMP,"orank %d must be equal on all processes, another process has value %d",orank,orankmax);
  }
#endif

  ierr = MPI_Comm_rank(((PetscObject)dm)->comm,&rank);CHKERRQ(ierr);
  /* create new link */
  ierr                = PetscNew(struct DMCompositeLink,&mine);CHKERRQ(ierr);
  mine->n             = n;
  mine->rank          = orank;
  mine->dm            = PETSC_NULL;
  mine->type          = DMCOMPOSITE_ARRAY;
  mine->next          = PETSC_NULL;
  if (rank == mine->rank) {com->n += n;com->nmine++;}

  /* add to end of list */
  if (!next) {
    com->next = mine;
  } else {
    while (next->next) next = next->next;
    next->next = mine;
  }
  com->nredundant++;
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeAddDM"
/*@C
    DMCompositeAddDM - adds a DM  vector to a DMComposite

    Collective on DMComposite

    Input Parameter:
+    dm - the packer object
-    dm - the DM object, if the DM is a da you will need to caste it with a (DM)

    Level: advanced

.seealso DMDestroy(), DMCompositeGather(), DMCompositeAddDM(), DMCreateGlobalVector(),
         DMCompositeScatter(), DMCompositeCreate(), DMCompositeGetISLocalToGlobalMappings(), DMCompositeGetAccess(),
         DMCompositeGetLocalVectors(), DMCompositeRestoreLocalVectors(), DMCompositeGetEntries()

@*/
PetscErrorCode PETSCDM_DLLEXPORT DMCompositeAddDM(DM dmc,DM dm)
{
  PetscErrorCode         ierr;
  PetscInt               n;
  struct DMCompositeLink *mine,*next;
  Vec                    global;
  DM_Composite           *com = (DM_Composite*)dmc->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dmc,DM_CLASSID,1);
  PetscValidHeaderSpecific(dm,DM_CLASSID,2);
  next = com->next;
  if (com->setup) SETERRQ(((PetscObject)dmc)->comm,PETSC_ERR_ARG_WRONGSTATE,"Cannot add a DM once you have used the DMComposite");

  /* create new link */
  ierr = PetscNew(struct DMCompositeLink,&mine);CHKERRQ(ierr);
  ierr = PetscObjectReference((PetscObject)dm);CHKERRQ(ierr);
  ierr = DMGetGlobalVector(dm,&global);CHKERRQ(ierr);
  ierr = VecGetLocalSize(global,&n);CHKERRQ(ierr);
  ierr = DMRestoreGlobalVector(dm,&global);CHKERRQ(ierr);
  mine->n      = n;
  mine->dm     = dm;
  mine->type   = DMCOMPOSITE_DM;
  mine->next   = PETSC_NULL;
  com->n       += n;

  /* add to end of list */
  if (!next) {
    com->next = mine;
  } else {
    while (next->next) next = next->next;
    next->next = mine;
  }
  com->nDM++;
  com->nmine++;
  PetscFunctionReturn(0);
}

extern PetscErrorCode PETSCDM_DLLEXPORT VecView_MPI(Vec,PetscViewer);
EXTERN_C_BEGIN
#undef __FUNCT__
#define __FUNCT__ "VecView_DMComposite"
PetscErrorCode PETSCDM_DLLEXPORT VecView_DMComposite(Vec gvec,PetscViewer viewer)
{
  DM                     dm;
  PetscErrorCode         ierr;
  struct DMCompositeLink *next;
  PetscBool              isdraw;
  DM_Composite           *com;

  PetscFunctionBegin;
  ierr = PetscObjectQuery((PetscObject)gvec,"DMComposite",(PetscObject*)&dm);CHKERRQ(ierr);
  if (!dm) SETERRQ(((PetscObject)gvec)->comm,PETSC_ERR_ARG_WRONG,"Vector not generated from a DMComposite");
  com = (DM_Composite*)dm->data;
  next = com->next;

  ierr = PetscTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);CHKERRQ(ierr);
  if (!isdraw) {
    /* do I really want to call this? */
    ierr = VecView_MPI(gvec,viewer);CHKERRQ(ierr);
  } else {
    PetscInt cnt = 0;

    /* loop over packed objects, handling one at at time */
    while (next) {
      if (next->type == DMCOMPOSITE_ARRAY) {
	PetscScalar *array;
	ierr  = DMCompositeGetAccess_Array(dm,next,gvec,&array);CHKERRQ(ierr);

	/*skip it for now */
      } else if (next->type == DMCOMPOSITE_DM) {
	Vec      vec;
        PetscInt bs;

	ierr = DMCompositeGetAccess_DM(dm,next,gvec,&vec);CHKERRQ(ierr);
	ierr = VecView(vec,viewer);CHKERRQ(ierr);
        ierr = VecGetBlockSize(vec,&bs);CHKERRQ(ierr);
	ierr = DMCompositeRestoreAccess_DM(dm,next,gvec,&vec);CHKERRQ(ierr);
        ierr = PetscViewerDrawBaseAdd(viewer,bs);CHKERRQ(ierr);
        cnt += bs;
      } else {
	SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_SUP,"Cannot handle that object type yet");
      }
      next = next->next;
    }
    ierr = PetscViewerDrawBaseAdd(viewer,-cnt);CHKERRQ(ierr);
  }
  PetscFunctionReturn(0);
}
EXTERN_C_END


#undef __FUNCT__
#define __FUNCT__ "DMCreateGlobalVector_Composite"
PetscErrorCode PETSCDM_DLLEXPORT DMCreateGlobalVector_Composite(DM dm,Vec *gvec)
{
  PetscErrorCode         ierr;
  DM_Composite           *com = (DM_Composite*)dm->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm,DM_CLASSID,1);
  if (!com->setup) {
    ierr = DMSetUp(dm);CHKERRQ(ierr);
  }
  ierr = VecCreateMPI(((PetscObject)dm)->comm,com->n,com->N,gvec);CHKERRQ(ierr);
  ierr = PetscObjectCompose((PetscObject)*gvec,"DMComposite",(PetscObject)dm);CHKERRQ(ierr);
  ierr = VecSetOperation(*gvec,VECOP_VIEW,(void(*)(void))VecView_DMComposite);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCreateLocalVector_Composite"
PetscErrorCode PETSCDM_DLLEXPORT DMCreateLocalVector_Composite(DM dm,Vec *lvec)
{
  PetscErrorCode         ierr;
  DM_Composite           *com = (DM_Composite*)dm->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm,DM_CLASSID,1);
  if (!com->setup) {
    ierr = DMSetUp(dm);CHKERRQ(ierr);
  }
  ierr = VecCreateSeq(((PetscObject)dm)->comm,com->nghost,lvec);CHKERRQ(ierr);
  ierr = PetscObjectCompose((PetscObject)*lvec,"DMComposite",(PetscObject)dm);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeGetISLocalToGlobalMappings"
/*@C
    DMCompositeGetISLocalToGlobalMappings - gets an ISLocalToGlobalMapping for each DM/array in the DMComposite, maps to the composite global space

    Collective on DMComposite

    Input Parameter:
.    dm - the packer object

    Output Parameters:
.    ltogs - the individual mappings for each packed vector/array. Note that this includes
           all the ghost points that individual ghosted DMDA's may have. Also each process has an
           mapping for EACH redundant array (not just the local redundant arrays).

    Level: advanced

    Notes:
       Each entry of ltogs should be destroyed with ISLocalToGlobalMappingDestroy(), the ltogs array should be freed with PetscFree().

.seealso DMDestroy(), DMCompositeAddArray(), DMCompositeAddDM(), DMCreateGlobalVector(),
         DMCompositeGather(), DMCompositeCreate(), DMCompositeGetAccess(), DMCompositeScatter(),
         DMCompositeGetLocalVectors(), DMCompositeRestoreLocalVectors(),DMCompositeGetEntries()

@*/
PetscErrorCode PETSCDM_DLLEXPORT DMCompositeGetISLocalToGlobalMappings(DM dm,ISLocalToGlobalMapping **ltogs)
{
  PetscErrorCode         ierr;
  PetscInt               i,*idx,n,cnt;
  struct DMCompositeLink *next;
  PetscMPIInt            rank;
  DM_Composite           *com = (DM_Composite*)dm->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm,DM_CLASSID,1);
  ierr = PetscMalloc(com->nmine*sizeof(ISLocalToGlobalMapping),ltogs);CHKERRQ(ierr);
  next = com->next;
  ierr = MPI_Comm_rank(((PetscObject)dm)->comm,&rank);CHKERRQ(ierr);

  /* loop over packed objects, handling one at at time */
  cnt = 0;
  while (next) {
    if (next->type == DMCOMPOSITE_ARRAY) {
      ierr = PetscMalloc(next->n*sizeof(PetscInt),&idx);CHKERRQ(ierr);
      if (rank == next->rank) {
        for (i=0; i<next->n; i++) idx[i] = next->grstart + i;
      }
      ierr = MPI_Bcast(idx,next->n,MPIU_INT,next->rank,((PetscObject)dm)->comm);CHKERRQ(ierr);
      ierr = ISLocalToGlobalMappingCreate(((PetscObject)dm)->comm,next->n,idx,PETSC_OWN_POINTER,&(*ltogs)[cnt]);CHKERRQ(ierr);
    } else if (next->type == DMCOMPOSITE_DM) {
      ISLocalToGlobalMapping ltog;
      PetscMPIInt            size;
      const PetscInt         *suboff;
      Vec                    global;

      /* Get sub-DM global indices for each local dof */
      ierr = DMDAGetISLocalToGlobalMapping(next->dm,&ltog);CHKERRQ(ierr); /* This function should become generic to DM */
      ierr = ISLocalToGlobalMappingGetSize(ltog,&n);CHKERRQ(ierr);
      ierr = PetscMalloc(n*sizeof(PetscInt),&idx);CHKERRQ(ierr);
      for (i=0; i<n; i++) idx[i] = i;
      ierr = ISLocalToGlobalMappingApply(ltog,n,idx,idx);CHKERRQ(ierr); /* This would be nicer with an ISLocalToGlobalMappingGetIndices() */

      /* Get the offsets for the sub-DM global vector */
      ierr = DMGetGlobalVector(next->dm,&global);CHKERRQ(ierr);
      ierr = VecGetOwnershipRanges(global,&suboff);CHKERRQ(ierr);
      ierr = MPI_Comm_size(((PetscObject)global)->comm,&size);CHKERRQ(ierr);

      /* Shift the sub-DM definition of the global space to the composite global space */
      for (i=0; i<n; i++) {
        PetscInt subi = idx[i],lo = 0,hi = size,t;
        /* Binary search to find which rank owns subi */
        while (hi-lo > 1) {
          t = lo + (hi-lo)/2;
          if (suboff[t] > subi) hi = t;
          else                  lo = t;
        }
        idx[i] = subi - suboff[lo] + next->grstarts[lo];
      }
      ierr = ISLocalToGlobalMappingCreate(((PetscObject)dm)->comm,n,idx,PETSC_OWN_POINTER,&(*ltogs)[cnt]);CHKERRQ(ierr);
      ierr = DMRestoreGlobalVector(next->dm,&global);CHKERRQ(ierr);
    } else SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_SUP,"Cannot handle that object type yet");
    next = next->next;
    cnt++;
  }
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeGetGlobalISs"
/*@C
    DMCompositeGetGlobalISs - Gets the index sets for each composed object

    Collective on DMComposite

    Input Parameter:
.    dm - the packer object

    Output Parameters:
.    is - the array of index sets

    Level: advanced

    Notes:
       The is entries should be destroyed with ISDestroy(), the is array should be freed with PetscFree()

       The number of IS on each process will/may be different when redundant arrays are used

       These could be used to extract a subset of vector entries for a "multi-physics" preconditioner

       Use DMCompositeGetLocalISs() for index sets in the packed local numbering, and
       DMCompositeGetISLocalToGlobalMappings() for to map local sub-DM (including ghost) indices to packed global
       indices.

.seealso DMDestroy(), DMCompositeAddArray(), DMCompositeAddDM(), DMCreateGlobalVector(),
         DMCompositeGather(), DMCompositeCreate(), DMCompositeGetAccess(), DMCompositeScatter(),
         DMCompositeGetLocalVectors(), DMCompositeRestoreLocalVectors(),DMCompositeGetEntries()

@*/

PetscErrorCode PETSCDM_DLLEXPORT DMCompositeGetGlobalISs(DM dm,IS *is[])
{
  PetscErrorCode         ierr;
  PetscInt               cnt = 0,*idx,i;
  struct DMCompositeLink *next;
  PetscMPIInt            rank;
  DM_Composite           *com = (DM_Composite*)dm->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm,DM_CLASSID,1);
  ierr = PetscMalloc(com->nmine*sizeof(IS),is);CHKERRQ(ierr);
  next = com->next;
  ierr = MPI_Comm_rank(((PetscObject)dm)->comm,&rank);CHKERRQ(ierr);

  /* loop over packed objects, handling one at at time */
  while (next) {

    if (next->type == DMCOMPOSITE_ARRAY) {

      if (rank == next->rank) {
        ierr = PetscMalloc(next->n*sizeof(PetscInt),&idx);CHKERRQ(ierr);
        for (i=0; i<next->n; i++) idx[i] = next->grstart + i;
        ierr = ISCreateGeneral(((PetscObject)dm)->comm,next->n,idx,PETSC_OWN_POINTER,&(*is)[cnt]);CHKERRQ(ierr);
        cnt++;
      }

    } else if (next->type == DMCOMPOSITE_DM) {
      ierr = PetscMalloc(next->n*sizeof(PetscInt),&idx);CHKERRQ(ierr);
      for (i=0; i<next->n; i++) idx[i] = next->grstart + i;
      ierr = ISCreateGeneral(((PetscObject)dm)->comm,next->n,idx,PETSC_OWN_POINTER,&(*is)[cnt]);CHKERRQ(ierr);
      cnt++;
    } else {
      SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_SUP,"Cannot handle that object type yet");
    }
    next = next->next;
  }
  PetscFunctionReturn(0);
}

/* -------------------------------------------------------------------------------------*/
#undef __FUNCT__
#define __FUNCT__ "DMCompositeGetLocalVectors_Array"
PetscErrorCode DMCompositeGetLocalVectors_Array(DM dm,struct DMCompositeLink *mine,PetscScalar **array)
{
  PetscErrorCode ierr;
  PetscFunctionBegin;
  if (array) {
    ierr = PetscMalloc(mine->n*sizeof(PetscScalar),array);CHKERRQ(ierr);
  }
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeGetLocalVectors_DM"
PetscErrorCode DMCompositeGetLocalVectors_DM(DM dm,struct DMCompositeLink *mine,Vec *local)
{
  PetscErrorCode ierr;
  PetscFunctionBegin;
  if (local) {
    ierr = DMGetLocalVector(mine->dm,local);CHKERRQ(ierr);
  }
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeRestoreLocalVectors_Array"
PetscErrorCode DMCompositeRestoreLocalVectors_Array(DM dm,struct DMCompositeLink *mine,PetscScalar **array)
{
  PetscErrorCode ierr;
  PetscFunctionBegin;
  if (array) {
    ierr = PetscFree(*array);CHKERRQ(ierr);
  }
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeRestoreLocalVectors_DM"
PetscErrorCode DMCompositeRestoreLocalVectors_DM(DM dm,struct DMCompositeLink *mine,Vec *local)
{
  PetscErrorCode ierr;
  PetscFunctionBegin;
  if (local) {
    ierr = DMRestoreLocalVector(mine->dm,local);CHKERRQ(ierr);
  }
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeGetLocalVectors"
/*@C
    DMCompositeGetLocalVectors - Gets local vectors and arrays for each part of a DMComposite.
       Use DMCompositeRestoreLocalVectors() to return them.

    Not Collective

    Input Parameter:
.    dm - the packer object

    Output Parameter:
.    ... - the individual sequential objects (arrays or vectors)

    Level: advanced

.seealso DMDestroy(), DMCompositeAddArray(), DMCompositeAddDM(), DMCreateGlobalVector(),
         DMCompositeGather(), DMCompositeCreate(), DMCompositeGetISLocalToGlobalMappings(), DMCompositeGetAccess(),
         DMCompositeRestoreLocalVectors(), DMCompositeScatter(), DMCompositeGetEntries()

@*/
PetscErrorCode PETSCDM_DLLEXPORT DMCompositeGetLocalVectors(DM dm,...)
{
  va_list                Argp;
  PetscErrorCode         ierr;
  struct DMCompositeLink *next;
  DM_Composite           *com = (DM_Composite*)dm->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm,DM_CLASSID,1);
  next = com->next;
  /* loop over packed objects, handling one at at time */
  va_start(Argp,dm);
  while (next) {
    if (next->type == DMCOMPOSITE_ARRAY) {
      PetscScalar **array;
      array = va_arg(Argp, PetscScalar**);
      ierr = DMCompositeGetLocalVectors_Array(dm,next,array);CHKERRQ(ierr);
    } else if (next->type == DMCOMPOSITE_DM) {
      Vec *vec;
      vec = va_arg(Argp, Vec*);
      ierr = DMCompositeGetLocalVectors_DM(dm,next,vec);CHKERRQ(ierr);
    } else {
      SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_SUP,"Cannot handle that object type yet");
    }
    next = next->next;
  }
  va_end(Argp);
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeRestoreLocalVectors"
/*@C
    DMCompositeRestoreLocalVectors - Restores local vectors and arrays for each part of a DMComposite.

    Not Collective

    Input Parameter:
.    dm - the packer object

    Output Parameter:
.    ... - the individual sequential objects (arrays or vectors)

    Level: advanced

.seealso DMDestroy(), DMCompositeAddArray(), DMCompositeAddDM(), DMCreateGlobalVector(),
         DMCompositeGather(), DMCompositeCreate(), DMCompositeGetISLocalToGlobalMappings(), DMCompositeGetAccess(),
         DMCompositeGetLocalVectors(), DMCompositeScatter(), DMCompositeGetEntries()

@*/
PetscErrorCode PETSCDM_DLLEXPORT DMCompositeRestoreLocalVectors(DM dm,...)
{
  va_list                Argp;
  PetscErrorCode         ierr;
  struct DMCompositeLink *next;
  DM_Composite           *com = (DM_Composite*)dm->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm,DM_CLASSID,1);
  next = com->next;
  /* loop over packed objects, handling one at at time */
  va_start(Argp,dm);
  while (next) {
    if (next->type == DMCOMPOSITE_ARRAY) {
      PetscScalar **array;
      array = va_arg(Argp, PetscScalar**);
      ierr = DMCompositeRestoreLocalVectors_Array(dm,next,array);CHKERRQ(ierr);
    } else if (next->type == DMCOMPOSITE_DM) {
      Vec *vec;
      vec = va_arg(Argp, Vec*);
      ierr = DMCompositeRestoreLocalVectors_DM(dm,next,vec);CHKERRQ(ierr);
    } else {
      SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_SUP,"Cannot handle that object type yet");
    }
    next = next->next;
  }
  va_end(Argp);
  PetscFunctionReturn(0);
}

/* -------------------------------------------------------------------------------------*/
#undef __FUNCT__
#define __FUNCT__ "DMCompositeGetEntries_Array"
PetscErrorCode DMCompositeGetEntries_Array(DM dm,struct DMCompositeLink *mine,PetscInt *n)
{
  PetscFunctionBegin;
  if (n) *n = mine->n;
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeGetEntries_DM"
PetscErrorCode DMCompositeGetEntries_DM(DM dmi,struct DMCompositeLink *mine,DM *dm)
{
  PetscFunctionBegin;
  if (dm) *dm = mine->dm;
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMCompositeGetEntries"
/*@C
    DMCompositeGetEntries - Gets the DM, redundant size, etc for each entry in a DMComposite.

    Not Collective

    Input Parameter:
.    dm - the packer object

    Output Parameter:
.    ... - the individual entries, DMs or integer sizes)

    Level: advanced

.seealso DMDestroy(), DMCompositeAddArray(), DMCompositeAddDM(), DMCreateGlobalVector(),
         DMCompositeGather(), DMCompositeCreate(), DMCompositeGetISLocalToGlobalMappings(), DMCompositeGetAccess(),
         DMCompositeRestoreLocalVectors(), DMCompositeGetLocalVectors(),  DMCompositeScatter(),
         DMCompositeGetLocalVectors(), DMCompositeRestoreLocalVectors()

@*/
PetscErrorCode PETSCDM_DLLEXPORT DMCompositeGetEntries(DM dm,...)
{
  va_list                Argp;
  PetscErrorCode         ierr;
  struct DMCompositeLink *next;
  DM_Composite           *com = (DM_Composite*)dm->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm,DM_CLASSID,1);
  next = com->next;
  /* loop over packed objects, handling one at at time */
  va_start(Argp,dm);
  while (next) {
    if (next->type == DMCOMPOSITE_ARRAY) {
      PetscInt *n;
      n = va_arg(Argp, PetscInt*);
      ierr = DMCompositeGetEntries_Array(dm,next,n);CHKERRQ(ierr);
    } else if (next->type == DMCOMPOSITE_DM) {
      DM *dmn;
      dmn = va_arg(Argp, DM*);
      ierr = DMCompositeGetEntries_DM(dm,next,dmn);CHKERRQ(ierr);
    } else {
      SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_SUP,"Cannot handle that object type yet");
    }
    next = next->next;
  }
  va_end(Argp);
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMRefine_Composite"
PetscErrorCode PETSCDM_DLLEXPORT DMRefine_Composite(DM dmi,MPI_Comm comm,DM *fine)
{
  PetscErrorCode         ierr;
  struct DMCompositeLink *next;
  DM_Composite           *com = (DM_Composite*)dmi->data;
  DM                     dm;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dmi,DM_CLASSID,1);
  next = com->next;
  ierr = DMCompositeCreate(comm,fine);CHKERRQ(ierr);

  /* loop over packed objects, handling one at at time */
  while (next) {
    if (next->type == DMCOMPOSITE_ARRAY) {
      ierr = DMCompositeAddArray(*fine,next->rank,next->n);CHKERRQ(ierr);
    } else if (next->type == DMCOMPOSITE_DM) {
      ierr = DMRefine(next->dm,comm,&dm);CHKERRQ(ierr);
      ierr = DMCompositeAddDM(*fine,dm);CHKERRQ(ierr);
      ierr = PetscObjectDereference((PetscObject)dm);CHKERRQ(ierr);
    } else {
      SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_SUP,"Cannot handle that object type yet");
    }
    next = next->next;
  }
  PetscFunctionReturn(0);
}

#include "petscmat.h"

struct MatPackLink {
  Mat                A;
  struct MatPackLink *next;
};

struct MatPack {
  DM                 right,left;
  struct MatPackLink *next;
};

#undef __FUNCT__
#define __FUNCT__ "MatMultBoth_Shell_Pack"
PetscErrorCode MatMultBoth_Shell_Pack(Mat A,Vec x,Vec y,PetscBool  add)
{
  struct MatPack         *mpack;
  struct DMCompositeLink *xnext,*ynext;
  struct MatPackLink     *anext;
  PetscScalar            *xarray,*yarray;
  PetscErrorCode         ierr;
  PetscInt               i;
  Vec                    xglobal,yglobal;
  PetscMPIInt            rank;
  DM_Composite           *comright;
  DM_Composite           *comleft;

  PetscFunctionBegin;
  ierr = MatShellGetContext(A,(void**)&mpack);CHKERRQ(ierr);
  ierr = MPI_Comm_rank(((PetscObject)mpack->right)->comm,&rank);CHKERRQ(ierr);
  comright = (DM_Composite*)mpack->right->data;
  comleft = (DM_Composite*)mpack->left->data;
  xnext = comright->next;
  ynext = comleft->next;
  anext = mpack->next;

  while (xnext) {
    if (xnext->type == DMCOMPOSITE_ARRAY) {
      if (rank == xnext->rank) {
        ierr    = VecGetArray(x,&xarray);CHKERRQ(ierr);
        ierr    = VecGetArray(y,&yarray);CHKERRQ(ierr);
        if (add) {
          for (i=0; i<xnext->n; i++) {
            yarray[ynext->rstart+i] += xarray[xnext->rstart+i];
          }
        } else {
          ierr    = PetscMemcpy(yarray+ynext->rstart,xarray+xnext->rstart,xnext->n*sizeof(PetscScalar));CHKERRQ(ierr);
        }
        ierr    = VecRestoreArray(x,&xarray);CHKERRQ(ierr);
        ierr    = VecRestoreArray(y,&yarray);CHKERRQ(ierr);
      }
    } else if (xnext->type == DMCOMPOSITE_DM) {
      ierr  = VecGetArray(x,&xarray);CHKERRQ(ierr);
      ierr  = VecGetArray(y,&yarray);CHKERRQ(ierr);
      ierr  = DMGetGlobalVector(xnext->dm,&xglobal);CHKERRQ(ierr);
      ierr  = DMGetGlobalVector(ynext->dm,&yglobal);CHKERRQ(ierr);
      ierr  = VecPlaceArray(xglobal,xarray+xnext->rstart);CHKERRQ(ierr);
      ierr  = VecPlaceArray(yglobal,yarray+ynext->rstart);CHKERRQ(ierr);
      if (add) {
        ierr  = MatMultAdd(anext->A,xglobal,yglobal,yglobal);CHKERRQ(ierr);
      } else {
        ierr  = MatMult(anext->A,xglobal,yglobal);CHKERRQ(ierr);
      }
      ierr  = VecRestoreArray(x,&xarray);CHKERRQ(ierr);
      ierr  = VecRestoreArray(y,&yarray);CHKERRQ(ierr);
      ierr  = VecResetArray(xglobal);CHKERRQ(ierr);
      ierr  = VecResetArray(yglobal);CHKERRQ(ierr);
      ierr  = DMRestoreGlobalVector(xnext->dm,&xglobal);CHKERRQ(ierr);
      ierr  = DMRestoreGlobalVector(ynext->dm,&yglobal);CHKERRQ(ierr);
      anext = anext->next;
    } else {
      SETERRQ(((PetscObject)A)->comm,PETSC_ERR_SUP,"Cannot handle that object type yet");
    }
    xnext = xnext->next;
    ynext = ynext->next;
  }
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "MatMultAdd_Shell_Pack"
PetscErrorCode MatMultAdd_Shell_Pack(Mat A,Vec x,Vec y,Vec z)
{
  PetscErrorCode ierr;
  PetscFunctionBegin;
  if (z != y) SETERRQ(((PetscObject)A)->comm,PETSC_ERR_SUP,"Handles y == z only");
  ierr = MatMultBoth_Shell_Pack(A,x,y,PETSC_TRUE);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "MatMult_Shell_Pack"
PetscErrorCode MatMult_Shell_Pack(Mat A,Vec x,Vec y)
{
  PetscErrorCode ierr;
  PetscFunctionBegin;
  ierr = MatMultBoth_Shell_Pack(A,x,y,PETSC_FALSE);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "MatMultTranspose_Shell_Pack"
PetscErrorCode MatMultTranspose_Shell_Pack(Mat A,Vec x,Vec y)
{
  struct MatPack         *mpack;
  struct DMCompositeLink *xnext,*ynext;
  struct MatPackLink     *anext;
  PetscScalar            *xarray,*yarray;
  PetscErrorCode         ierr;
  Vec                    xglobal,yglobal;
  PetscMPIInt            rank;
  DM_Composite           *comright;
  DM_Composite           *comleft;

  PetscFunctionBegin;
  ierr  = MatShellGetContext(A,(void**)&mpack);CHKERRQ(ierr);
  ierr = MPI_Comm_rank(((PetscObject)mpack->right)->comm,&rank);CHKERRQ(ierr);
  comright = (DM_Composite*)mpack->right->data;
  comleft = (DM_Composite*)mpack->left->data;
  ynext = comright->next;
  xnext = comleft->next;
  anext = mpack->next;

  while (xnext) {
    if (xnext->type == DMCOMPOSITE_ARRAY) {
      if (rank == ynext->rank) {
        ierr    = VecGetArray(x,&xarray);CHKERRQ(ierr);
        ierr    = VecGetArray(y,&yarray);CHKERRQ(ierr);
        ierr    = PetscMemcpy(yarray+ynext->rstart,xarray+xnext->rstart,xnext->n*sizeof(PetscScalar));CHKERRQ(ierr);
        ierr    = VecRestoreArray(x,&xarray);CHKERRQ(ierr);
        ierr    = VecRestoreArray(y,&yarray);CHKERRQ(ierr);
      }
    } else if (xnext->type == DMCOMPOSITE_DM) {
      ierr  = VecGetArray(x,&xarray);CHKERRQ(ierr);
      ierr  = VecGetArray(y,&yarray);CHKERRQ(ierr);
      ierr  = DMGetGlobalVector(xnext->dm,&xglobal);CHKERRQ(ierr);
      ierr  = DMGetGlobalVector(ynext->dm,&yglobal);CHKERRQ(ierr);
      ierr  = VecPlaceArray(xglobal,xarray+xnext->rstart);CHKERRQ(ierr);
      ierr  = VecPlaceArray(yglobal,yarray+ynext->rstart);CHKERRQ(ierr);
      ierr  = MatMultTranspose(anext->A,xglobal,yglobal);CHKERRQ(ierr);
      ierr  = VecRestoreArray(x,&xarray);CHKERRQ(ierr);
      ierr  = VecRestoreArray(y,&yarray);CHKERRQ(ierr);
      ierr  = VecResetArray(xglobal);CHKERRQ(ierr);
      ierr  = VecResetArray(yglobal);CHKERRQ(ierr);
      ierr  = DMRestoreGlobalVector(xnext->dm,&xglobal);CHKERRQ(ierr);
      ierr  = DMRestoreGlobalVector(ynext->dm,&yglobal);CHKERRQ(ierr);
      anext = anext->next;
    } else {
      SETERRQ(((PetscObject)A)->comm,PETSC_ERR_SUP,"Cannot handle that object type yet");
    }
    xnext = xnext->next;
    ynext = ynext->next;
  }
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "MatDestroy_Shell_Pack"
PetscErrorCode MatDestroy_Shell_Pack(Mat A)
{
  struct MatPack     *mpack;
  struct MatPackLink *anext,*oldanext;
  PetscErrorCode     ierr;

  PetscFunctionBegin;
  ierr  = MatShellGetContext(A,(void**)&mpack);CHKERRQ(ierr);
  anext = mpack->next;

  while (anext) {
    ierr     = MatDestroy(anext->A);CHKERRQ(ierr);
    oldanext = anext;
    anext    = anext->next;
    ierr     = PetscFree(oldanext);CHKERRQ(ierr);
  }
  ierr = PetscFree(mpack);CHKERRQ(ierr);
  ierr = PetscObjectChangeTypeName((PetscObject)A,0);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMGetInterpolation_Composite"
PetscErrorCode PETSCDM_DLLEXPORT DMGetInterpolation_Composite(DM coarse,DM fine,Mat *A,Vec *v)
{
  PetscErrorCode         ierr;
  PetscInt               m,n,M,N;
  struct DMCompositeLink *nextc;
  struct DMCompositeLink *nextf;
  struct MatPackLink     *nextmat,*pnextmat = 0;
  struct MatPack         *mpack;
  Vec                    gcoarse,gfine;
  DM_Composite           *comcoarse = (DM_Composite*)coarse->data;
  DM_Composite           *comfine = (DM_Composite*)fine->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(coarse,DM_CLASSID,1);
  PetscValidHeaderSpecific(fine,DM_CLASSID,2);
  nextc = comcoarse->next;
  nextf = comfine->next;
  /* use global vectors only for determining matrix layout */
  ierr = DMCreateGlobalVector(coarse,&gcoarse);CHKERRQ(ierr);
  ierr = DMCreateGlobalVector(fine,&gfine);CHKERRQ(ierr);
  ierr = VecGetLocalSize(gcoarse,&n);CHKERRQ(ierr);
  ierr = VecGetLocalSize(gfine,&m);CHKERRQ(ierr);
  ierr = VecGetSize(gcoarse,&N);CHKERRQ(ierr);
  ierr = VecGetSize(gfine,&M);CHKERRQ(ierr);
  ierr = VecDestroy(gcoarse);CHKERRQ(ierr);
  ierr = VecDestroy(gfine);CHKERRQ(ierr);

  ierr         = PetscNew(struct MatPack,&mpack);CHKERRQ(ierr);
  mpack->right = coarse;
  mpack->left  = fine;
  ierr  = MatCreate(((PetscObject)fine)->comm,A);CHKERRQ(ierr);
  ierr  = MatSetSizes(*A,m,n,M,N);CHKERRQ(ierr);
  ierr  = MatSetType(*A,MATSHELL);CHKERRQ(ierr);
  ierr  = MatShellSetContext(*A,mpack);CHKERRQ(ierr);
  ierr  = MatShellSetOperation(*A,MATOP_MULT,(void(*)(void))MatMult_Shell_Pack);CHKERRQ(ierr);
  ierr  = MatShellSetOperation(*A,MATOP_MULT_TRANSPOSE,(void(*)(void))MatMultTranspose_Shell_Pack);CHKERRQ(ierr);
  ierr  = MatShellSetOperation(*A,MATOP_MULT_ADD,(void(*)(void))MatMultAdd_Shell_Pack);CHKERRQ(ierr);
  ierr  = MatShellSetOperation(*A,MATOP_DESTROY,(void(*)(void))MatDestroy_Shell_Pack);CHKERRQ(ierr);

  /* loop over packed objects, handling one at at time */
  while (nextc) {
    if (nextc->type != nextf->type) SETERRQ(((PetscObject)fine)->comm,PETSC_ERR_ARG_INCOMP,"Two DM have different layout");

    if (nextc->type == DMCOMPOSITE_ARRAY) {
      ;
    } else if (nextc->type == DMCOMPOSITE_DM) {
      ierr          = PetscNew(struct MatPackLink,&nextmat);CHKERRQ(ierr);
      nextmat->next = 0;
      if (pnextmat) {
        pnextmat->next = nextmat;
        pnextmat       = nextmat;
      } else {
        pnextmat    = nextmat;
        mpack->next = nextmat;
      }
      ierr = DMGetInterpolation(nextc->dm,nextf->dm,&nextmat->A,PETSC_NULL);CHKERRQ(ierr);
    } else {
      SETERRQ(((PetscObject)fine)->comm,PETSC_ERR_SUP,"Cannot handle that object type yet");
    }
    nextc = nextc->next;
    nextf = nextf->next;
  }
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMGetMatrix_Composite"
PetscErrorCode PETSCDM_DLLEXPORT DMGetMatrix_Composite(DM dm, const MatType mtype,Mat *J)
{
  PetscErrorCode         ierr;
  DM_Composite           *com = (DM_Composite*)dm->data;
  struct DMCompositeLink *next = com->next;
  PetscInt               m,*dnz,*onz,i,j,mA;
  Mat                    Atmp;
  PetscMPIInt            rank;
  PetscScalar            zero = 0.0;
  PetscBool              dense = PETSC_FALSE;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm,DM_CLASSID,1);

  /* use global vector to determine layout needed for matrix */
  m = com->n;
  ierr = MPI_Comm_rank(((PetscObject)dm)->comm,&rank);CHKERRQ(ierr);
  ierr = MatCreate(((PetscObject)dm)->comm,J);CHKERRQ(ierr);
  ierr = MatSetSizes(*J,m,m,PETSC_DETERMINE,PETSC_DETERMINE);CHKERRQ(ierr);
  ierr = MatSetType(*J,MATAIJ);CHKERRQ(ierr);

  /*
     Extremely inefficient but will compute entire Jacobian for testing
  */
  ierr = PetscOptionsGetBool(PETSC_NULL,"-dmcomposite_dense_jacobian",&dense,PETSC_NULL);CHKERRQ(ierr);
  if (dense) {
    PetscInt    rstart,rend,*indices;
    PetscScalar *values;

    mA    = com->N;
    ierr = MatMPIAIJSetPreallocation(*J,mA,PETSC_NULL,mA-m,PETSC_NULL);CHKERRQ(ierr);
    ierr = MatSeqAIJSetPreallocation(*J,mA,PETSC_NULL);CHKERRQ(ierr);

    ierr = MatGetOwnershipRange(*J,&rstart,&rend);CHKERRQ(ierr);
    ierr = PetscMalloc2(mA,PetscScalar,&values,mA,PetscInt,&indices);CHKERRQ(ierr);
    ierr = PetscMemzero(values,mA*sizeof(PetscScalar));CHKERRQ(ierr);
    for (i=0; i<mA; i++) indices[i] = i;
    for (i=rstart; i<rend; i++) {
      ierr = MatSetValues(*J,1,&i,mA,indices,values,INSERT_VALUES);CHKERRQ(ierr);
    }
    ierr = PetscFree2(values,indices);CHKERRQ(ierr);
    ierr = MatAssemblyBegin(*J,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
    ierr = MatAssemblyEnd(*J,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
    PetscFunctionReturn(0);
  }

  ierr = MatPreallocateInitialize(((PetscObject)dm)->comm,m,m,dnz,onz);CHKERRQ(ierr);
  /* loop over packed objects, handling one at at time */
  next = com->next;
  while (next) {
    if (next->type == DMCOMPOSITE_ARRAY) {
      if (rank == next->rank) {  /* zero the "little" block */
        for (j=com->rstart+next->rstart; j<com->rstart+next->rstart+next->n; j++) {
          for (i=com->rstart+next->rstart; i<com->rstart+next->rstart+next->n; i++) {
            ierr = MatPreallocateSet(j,1,&i,dnz,onz);CHKERRQ(ierr);
          }
        }
      }
    } else if (next->type == DMCOMPOSITE_DM) {
      PetscInt       nc,rstart,*ccols,maxnc;
      const PetscInt *cols,*rstarts;
      PetscMPIInt    proc;

      ierr = DMGetMatrix(next->dm,mtype,&Atmp);CHKERRQ(ierr);
      ierr = MatGetOwnershipRange(Atmp,&rstart,PETSC_NULL);CHKERRQ(ierr);
      ierr = MatGetOwnershipRanges(Atmp,&rstarts);CHKERRQ(ierr);
      ierr = MatGetLocalSize(Atmp,&mA,PETSC_NULL);CHKERRQ(ierr);

      maxnc = 0;
      for (i=0; i<mA; i++) {
        ierr  = MatGetRow(Atmp,rstart+i,&nc,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
        ierr  = MatRestoreRow(Atmp,rstart+i,&nc,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
        maxnc = PetscMax(nc,maxnc);
      }
      ierr = PetscMalloc(maxnc*sizeof(PetscInt),&ccols);CHKERRQ(ierr);
      for (i=0; i<mA; i++) {
        ierr = MatGetRow(Atmp,rstart+i,&nc,&cols,PETSC_NULL);CHKERRQ(ierr);
        /* remap the columns taking into how much they are shifted on each process */
        for (j=0; j<nc; j++) {
          proc = 0;
          while (cols[j] >= rstarts[proc+1]) proc++;
          ccols[j] = cols[j] + next->grstarts[proc] - rstarts[proc];
        }
        ierr = MatPreallocateSet(com->rstart+next->rstart+i,nc,ccols,dnz,onz);CHKERRQ(ierr);
        ierr = MatRestoreRow(Atmp,rstart+i,&nc,&cols,PETSC_NULL);CHKERRQ(ierr);
      }
      ierr = PetscFree(ccols);CHKERRQ(ierr);
      ierr = MatDestroy(Atmp);CHKERRQ(ierr);
    } else {
      SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_SUP,"Cannot handle that object type yet");
    }
    next = next->next;
  }
  if (com->FormCoupleLocations) {
    ierr = (*com->FormCoupleLocations)(dm,PETSC_NULL,dnz,onz,__rstart,__nrows,__start,__end);CHKERRQ(ierr);
  }
  ierr = MatMPIAIJSetPreallocation(*J,0,dnz,0,onz);CHKERRQ(ierr);
  ierr = MatSeqAIJSetPreallocation(*J,0,dnz);CHKERRQ(ierr);
  ierr = MatPreallocateFinalize(dnz,onz);CHKERRQ(ierr);

  next = com->next;
  while (next) {
    if (next->type == DMCOMPOSITE_ARRAY) {
      if (rank == next->rank) {
        for (j=com->rstart+next->rstart; j<com->rstart+next->rstart+next->n; j++) {
          for (i=com->rstart+next->rstart; i<com->rstart+next->rstart+next->n; i++) {
            ierr = MatSetValues(*J,1,&j,1,&i,&zero,INSERT_VALUES);CHKERRQ(ierr);
          }
        }
      }
    } else if (next->type == DMCOMPOSITE_DM) {
      PetscInt          nc,rstart,row,maxnc,*ccols;
      const PetscInt    *cols,*rstarts;
      const PetscScalar *values;
      PetscMPIInt       proc;

      ierr = DMGetMatrix(next->dm,mtype,&Atmp);CHKERRQ(ierr);
      ierr = MatGetOwnershipRange(Atmp,&rstart,PETSC_NULL);CHKERRQ(ierr);
      ierr = MatGetOwnershipRanges(Atmp,&rstarts);CHKERRQ(ierr);
      ierr = MatGetLocalSize(Atmp,&mA,PETSC_NULL);CHKERRQ(ierr);
      maxnc = 0;
      for (i=0; i<mA; i++) {
        ierr  = MatGetRow(Atmp,rstart+i,&nc,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
        ierr  = MatRestoreRow(Atmp,rstart+i,&nc,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
        maxnc = PetscMax(nc,maxnc);
      }
      ierr = PetscMalloc(maxnc*sizeof(PetscInt),&ccols);CHKERRQ(ierr);
      for (i=0; i<mA; i++) {
        ierr = MatGetRow(Atmp,rstart+i,&nc,(const PetscInt **)&cols,&values);CHKERRQ(ierr);
        for (j=0; j<nc; j++) {
          proc = 0;
          while (cols[j] >= rstarts[proc+1]) proc++;
          ccols[j] = cols[j] + next->grstarts[proc] - rstarts[proc];
        }
        row  = com->rstart+next->rstart+i;
        ierr = MatSetValues(*J,1,&row,nc,ccols,values,INSERT_VALUES);CHKERRQ(ierr);
        ierr = MatRestoreRow(Atmp,rstart+i,&nc,(const PetscInt **)&cols,&values);CHKERRQ(ierr);
      }
      ierr = PetscFree(ccols);CHKERRQ(ierr);
      ierr = MatDestroy(Atmp);CHKERRQ(ierr);
    } else {
      SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_SUP,"Cannot handle that object type yet");
    }
    next = next->next;
  }
  if (com->FormCoupleLocations) {
    PetscInt __rstart;
    ierr = MatGetOwnershipRange(*J,&__rstart,PETSC_NULL);CHKERRQ(ierr);
    ierr = (*com->FormCoupleLocations)(dm,*J,PETSC_NULL,PETSC_NULL,__rstart,0,0,0);CHKERRQ(ierr);
  }
  ierr = MatAssemblyBegin(*J,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
  ierr = MatAssemblyEnd(*J,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMGetColoring_Composite"
PetscErrorCode PETSCDM_DLLEXPORT DMGetColoring_Composite(DM dm,ISColoringType ctype,const MatType mtype,ISColoring *coloring)
{
  PetscErrorCode         ierr;
  PetscInt               n,i,cnt;
  ISColoringValue        *colors;
  PetscBool              dense = PETSC_FALSE;
  ISColoringValue        maxcol = 0;
  DM_Composite           *com = (DM_Composite*)dm->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm,DM_CLASSID,1);
  if (ctype == IS_COLORING_GHOSTED) {
    SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_SUP,"Currently you must use -dmmg_iscoloring_type global" );
  } else if (ctype == IS_COLORING_GLOBAL) {
    n = com->n;
  } else SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_ARG_OUTOFRANGE,"Unknown ISColoringType");
  ierr = PetscMalloc(n*sizeof(ISColoringValue),&colors);CHKERRQ(ierr); /* freed in ISColoringDestroy() */

  ierr = PetscOptionsGetBool(PETSC_NULL,"-dmcomposite_dense_jacobian",&dense,PETSC_NULL);CHKERRQ(ierr);
  if (dense) {
    for (i=0; i<n; i++) {
      colors[i] = (ISColoringValue)(com->rstart + i);
    }
    maxcol = com->N;
  } else {
    struct DMCompositeLink *next = com->next;
    PetscMPIInt            rank;

    ierr = MPI_Comm_rank(((PetscObject)dm)->comm,&rank);CHKERRQ(ierr);
    cnt  = 0;
    while (next) {
      if (next->type == DMCOMPOSITE_ARRAY) {
        if (rank == next->rank) {  /* each column gets is own color */
          for (i=com->rstart+next->rstart; i<com->rstart+next->rstart+next->n; i++) {
            colors[cnt++] = maxcol++;
          }
        }
        ierr = MPI_Bcast(&maxcol,1,MPIU_COLORING_VALUE,next->rank,((PetscObject)dm)->comm);CHKERRQ(ierr);
      } else if (next->type == DMCOMPOSITE_DM) {
        ISColoring     lcoloring;

        ierr = DMGetColoring(next->dm,IS_COLORING_GLOBAL,mtype,&lcoloring);CHKERRQ(ierr);
        for (i=0; i<lcoloring->N; i++) {
          colors[cnt++] = maxcol + lcoloring->colors[i];
        }
        maxcol += lcoloring->n;
        ierr = ISColoringDestroy(lcoloring);CHKERRQ(ierr);
      } else {
        SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_SUP,"Cannot handle that object type yet");
      }
      next = next->next;
    }
  }
  ierr = ISColoringCreate(((PetscObject)dm)->comm,maxcol,n,colors,coloring);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMGlobalToLocalBegin_Composite"
PetscErrorCode PETSCDM_DLLEXPORT DMGlobalToLocalBegin_Composite(DM dm,Vec gvec,InsertMode mode,Vec lvec)
{
  PetscErrorCode         ierr;
  struct DMCompositeLink *next;
  PetscInt               cnt = 3;
  PetscMPIInt            rank;
  PetscScalar            *garray,*larray;
  DM_Composite           *com = (DM_Composite*)dm->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm,DM_CLASSID,1);
  PetscValidHeaderSpecific(gvec,VEC_CLASSID,2);
  next = com->next;
  if (!com->setup) {
    ierr = DMSetUp(dm);CHKERRQ(ierr);
  }
  ierr = MPI_Comm_rank(((PetscObject)dm)->comm,&rank);CHKERRQ(ierr);
  ierr = VecGetArray(gvec,&garray);CHKERRQ(ierr);
  ierr = VecGetArray(lvec,&larray);CHKERRQ(ierr);

  /* loop over packed objects, handling one at at time */
  while (next) {
    if (next->type == DMCOMPOSITE_ARRAY) {
      if (rank == next->rank) {
        ierr    = PetscMemcpy(larray,garray,next->n*sizeof(PetscScalar));CHKERRQ(ierr);
        garray += next->n;
      }
      /* does not handle ADD_VALUES */
      ierr = MPI_Bcast(larray,next->n,MPIU_SCALAR,next->rank,((PetscObject)dm)->comm);CHKERRQ(ierr);
      larray += next->n;
    } else if (next->type == DMCOMPOSITE_DM) {
      Vec      local,global;
      PetscInt N;

      ierr = DMGetGlobalVector(next->dm,&global);CHKERRQ(ierr);
      ierr = VecGetLocalSize(global,&N);CHKERRQ(ierr);
      ierr = VecPlaceArray(global,garray);CHKERRQ(ierr);
      ierr = DMGetLocalVector(next->dm,&local);CHKERRQ(ierr);
      ierr = VecPlaceArray(local,larray);CHKERRQ(ierr);
      ierr = DMGlobalToLocalBegin(next->dm,global,mode,local);CHKERRQ(ierr);
      ierr = DMGlobalToLocalEnd(next->dm,global,mode,local);CHKERRQ(ierr);
      ierr = VecResetArray(global);CHKERRQ(ierr);
      ierr = VecResetArray(local);CHKERRQ(ierr);
      ierr = DMRestoreGlobalVector(next->dm,&global);CHKERRQ(ierr);
      ierr = DMRestoreGlobalVector(next->dm,&local);CHKERRQ(ierr);
      larray += next->n;
    } else {
      SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_SUP,"Cannot handle that object type yet");
    }
    cnt++;
    next = next->next;
  }

  ierr = VecRestoreArray(gvec,PETSC_NULL);CHKERRQ(ierr);
  ierr = VecRestoreArray(lvec,PETSC_NULL);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

#undef __FUNCT__
#define __FUNCT__ "DMGlobalToLocalEnd_Composite"
PetscErrorCode PETSCDM_DLLEXPORT DMGlobalToLocalEnd_Composite(DM dm,Vec gvec,InsertMode mode,Vec lvec)
{
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}

EXTERN_C_BEGIN
#undef __FUNCT__
#define __FUNCT__ "DMCreate_Composite"
PetscErrorCode PETSCDM_DLLEXPORT DMCreate_Composite(DM p)
{
  PetscErrorCode ierr;
  DM_Composite   *com;

  PetscFunctionBegin;
  ierr = PetscNewLog(p,DM_Composite,&com);CHKERRQ(ierr);
  p->data = com;
  ierr = PetscObjectChangeTypeName((PetscObject)p,"DMComposite");CHKERRQ(ierr);
  com->n            = 0;
  com->next         = PETSC_NULL;
  com->nredundant   = 0;
  com->nDM          = 0;

  p->ops->createglobalvector = DMCreateGlobalVector_Composite;
  p->ops->createlocalvector  = DMCreateLocalVector_Composite;
  p->ops->refine             = DMRefine_Composite;
  p->ops->getinterpolation   = DMGetInterpolation_Composite;
  p->ops->getmatrix          = DMGetMatrix_Composite;
  p->ops->getcoloring        = DMGetColoring_Composite;
  p->ops->globaltolocalbegin = DMGlobalToLocalBegin_Composite;
  p->ops->globaltolocalend   = DMGlobalToLocalEnd_Composite;
  p->ops->destroy            = DMDestroy_Composite;
  p->ops->view               = DMView_Composite;
  p->ops->setup              = DMSetUp_Composite;
  PetscFunctionReturn(0);
}
EXTERN_C_END

#undef __FUNCT__
#define __FUNCT__ "DMCompositeCreate"
/*@C
    DMCompositeCreate - Creates a vector packer, used to generate "composite"
      vectors made up of several subvectors.

    Collective on MPI_Comm

    Input Parameter:
.   comm - the processors that will share the global vector

    Output Parameters:
.   packer - the packer object

    Level: advanced

.seealso DMDestroy(), DMCompositeAddArray(), DMCompositeAddDM(), DMCompositeScatter(),
         DMCompositeGather(), DMCreateGlobalVector(), DMCompositeGetISLocalToGlobalMappings(), DMCompositeGetAccess()
         DMCompositeGetLocalVectors(), DMCompositeRestoreLocalVectors(), DMCompositeGetEntries()

@*/
PetscErrorCode PETSCDM_DLLEXPORT DMCompositeCreate(MPI_Comm comm,DM *packer)
{
  PetscErrorCode ierr;

  PetscFunctionBegin;
  PetscValidPointer(packer,2);
  ierr = DMCreate(comm,packer);CHKERRQ(ierr);
  ierr = DMSetType(*packer,DMCOMPOSITE);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}