Actual source code: shellcnv.c
petsc-3.10.5 2019-03-28
Report Typos and Errors

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

      4: PetscErrorCode MatConvert_Shell(Mat oldmat, MatType newtype,MatReuse reuse,Mat *newmat)
      5: {
      6:   Mat            mat;
      7:   Vec            in,out;
      9:   PetscInt       i,m,n,M,N,*rows,start;
     10:   MPI_Comm       comm;
     11:   PetscScalar    *array;

     14:   PetscObjectGetComm((PetscObject)oldmat,&comm);

     16:   MatGetOwnershipRange(oldmat,&start,NULL);
     17:   MatCreateVecs(oldmat,&in,&out);
     18:   MatGetLocalSize(oldmat,&m,&n);
     19:   MatGetSize(oldmat,&M,&N);
     20:   PetscMalloc1(m,&rows);
     21:   for (i=0; i<m; i++) rows[i] = start + i;

     23:   MatCreate(comm,&mat);
     24:   MatSetSizes(mat,m,n,M,N);
     25:   MatSetType(mat,newtype);
     26:   MatSetBlockSizesFromMats(mat,oldmat,oldmat);
     27:   MatSetUp(mat);
     28:   VecSetOption(in,VEC_IGNORE_OFF_PROC_ENTRIES,PETSC_TRUE);

     30:   for (i=0; i<N; i++) {
     31:     VecZeroEntries(in);
     32:     VecSetValue(in,i,1.,INSERT_VALUES);
     33:     VecAssemblyBegin(in);
     34:     VecAssemblyEnd(in);

     36:     MatMult(oldmat,in,out);

     38:     VecGetArray(out,&array);
     39:     MatSetValues(mat,m,rows,1,&i,array,INSERT_VALUES);
     40:     VecRestoreArray(out,&array);

     42:   }
     43:   PetscFree(rows);
     44:   VecDestroy(&in);
     45:   VecDestroy(&out);
     46:   MatAssemblyBegin(mat,MAT_FINAL_ASSEMBLY);
     47:   MatAssemblyEnd(mat,MAT_FINAL_ASSEMBLY);

     49:   if (reuse == MAT_INPLACE_MATRIX) {
     50:     MatHeaderReplace(oldmat,&mat);
     51:   } else {
     52:     *newmat = mat;
     53:   }
     54:   return(0);
     55: }