#include <../src/mat/impls/baij/mpi/mpibaij.h> /*I "petscmat.h" I*/
#include <../src/mat/impls/aij/mpi/mpiaij.h>
#include <petsc/private/matimpl.h>
#include <petscmat.h>

PETSC_INTERN PetscErrorCode MatConvert_MPIAIJ_MPIBAIJ(Mat A, MatType newtype,MatReuse reuse,Mat *newmat)
{
  Mat               M;
  Mat_MPIAIJ        *mpimat = (Mat_MPIAIJ*)A->data;
  Mat_SeqAIJ        *Aa     = (Mat_SeqAIJ*)mpimat->A->data,*Ba = (Mat_SeqAIJ*)mpimat->B->data;
  PetscInt          *d_nnz,*o_nnz;
  PetscInt          i,m,n,lm,ln,bs=PetscAbs(A->rmap->bs);

  PetscFunctionBegin;
  if (reuse != MAT_REUSE_MATRIX) {
    PetscCall(MatGetSize(A,&m,&n));
    PetscCall(MatGetLocalSize(A,&lm,&ln));
    PetscCall(PetscMalloc2(lm/bs,&d_nnz,lm/bs,&o_nnz));

    for (i=0; i<lm/bs; i++) {
      d_nnz[i] = (Aa->i[i*bs+1] - Aa->i[i*bs])/bs;
      o_nnz[i] = (Ba->i[i*bs+1] - Ba->i[i*bs])/bs;
    }

    PetscCall(MatCreate(PetscObjectComm((PetscObject)A),&M));
    PetscCall(MatSetSizes(M,lm,ln,m,n));
    PetscCall(MatSetType(M,MATMPIBAIJ));
    PetscCall(MatSeqBAIJSetPreallocation(M,bs,0,d_nnz));
    PetscCall(MatMPIBAIJSetPreallocation(M,bs,0,d_nnz,0,o_nnz));
    PetscCall(PetscFree2(d_nnz,o_nnz));
  } else M = *newmat;

  /* reuse may not be equal to MAT_REUSE_MATRIX, but the basic converter will reallocate or replace newmat if this value is not used */
  /* if reuse is equal to MAT_INITIAL_MATRIX, it has been appropriately preallocated before                                          */
  /*                      MAT_INPLACE_MATRIX, it will be replaced with MatHeaderReplace below                                        */
  PetscCall(MatConvert_Basic(A,newtype,MAT_REUSE_MATRIX,&M));

  if (reuse == MAT_INPLACE_MATRIX) {
    PetscCall(MatHeaderReplace(A,&M));
  } else *newmat = M;
  PetscFunctionReturn(0);
}