2: #include <petsc-private/matimpl.h>

  6: /* 
  7:   MatConvert_Basic - Converts from any input format to another format. For
  8:   parallel formats, the new matrix distribution is determined by PETSc.

 10:   Does not do preallocation so in general will be slow
 11:  */
 12: PetscErrorCode MatConvert_Basic(Mat mat, const MatType newtype,MatReuse reuse,Mat *newmat)
 13: {
 14:   Mat                M;
 15:   const PetscScalar  *vwork;
 16:   PetscErrorCode     ierr;
 17:   PetscInt           i,nz,m,n,rstart,rend,lm,ln;
 18:   const PetscInt     *cwork;
 19:   PetscBool          isseqsbaij,ismpisbaij;

 22:   MatGetSize(mat,&m,&n);
 23:   MatGetLocalSize(mat,&lm,&ln);

 25:   if (ln == n) ln = PETSC_DECIDE; /* try to preserve column ownership */
 26: 
 27:   MatCreate(((PetscObject)mat)->comm,&M);
 28:   MatSetSizes(M,lm,ln,m,n);
 29:   MatSetBlockSize(M,mat->rmap->bs);
 30:   MatSetType(M,newtype);
 31:   PetscObjectTypeCompare((PetscObject)M,MATSEQSBAIJ,&isseqsbaij);
 32:   PetscObjectTypeCompare((PetscObject)M,MATMPISBAIJ,&ismpisbaij);
 33:   MatSetUp(M);
 34:   if (isseqsbaij || ismpisbaij) {MatSetOption(M,MAT_IGNORE_LOWER_TRIANGULAR,PETSC_TRUE);}

 36:   MatGetOwnershipRange(mat,&rstart,&rend);
 37:   for (i=rstart; i<rend; i++) {
 38:     MatGetRow(mat,i,&nz,&cwork,&vwork);
 39:     MatSetValues(M,1,&i,nz,cwork,vwork,INSERT_VALUES);
 40:     MatRestoreRow(mat,i,&nz,&cwork,&vwork);
 41:   }
 42:   MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY);
 43:   MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY);

 45:   if (reuse == MAT_REUSE_MATRIX) {
 46:     MatHeaderReplace(mat,M);
 47:   } else {
 48:     *newmat = M;
 49:   }
 50:   return(0);
 51: }