Actual source code: ex21.c


  2: static char help[] = "Tests converting a parallel AIJ formatted matrix to the parallel Row format.\n\
  3:  This also tests MatGetRow() and MatRestoreRow() for the parallel case.\n\n";

  5: #include <petscmat.h>

  7: int main(int argc, char **args)
  8: {
  9:   Mat                C, A;
 10:   PetscInt           i, j, m = 3, n = 2, Ii, J, rstart, rend, nz;
 11:   PetscMPIInt        rank, size;
 12:   const PetscInt    *idx;
 13:   PetscScalar        v;
 14:   const PetscScalar *values;

 16:   PetscFunctionBeginUser;
 17:   PetscCall(PetscInitialize(&argc, &args, (char *)0, help));
 18:   PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
 19:   PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
 20:   n = 2 * size;

 22:   /* create the matrix for the five point stencil, YET AGAIN*/
 23:   PetscCall(MatCreate(PETSC_COMM_WORLD, &C));
 24:   PetscCall(MatSetSizes(C, PETSC_DECIDE, PETSC_DECIDE, m * n, m * n));
 25:   PetscCall(MatSetFromOptions(C));
 26:   PetscCall(MatMPIAIJSetPreallocation(C, 5, NULL, 5, NULL));
 27:   PetscCall(MatSeqAIJSetPreallocation(C, 5, NULL));
 28:   for (i = 0; i < m; i++) {
 29:     for (j = 2 * rank; j < 2 * rank + 2; j++) {
 30:       v  = -1.0;
 31:       Ii = j + n * i;
 32:       if (i > 0) {
 33:         J = Ii - n;
 34:         PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
 35:       }
 36:       if (i < m - 1) {
 37:         J = Ii + n;
 38:         PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
 39:       }
 40:       if (j > 0) {
 41:         J = Ii - 1;
 42:         PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
 43:       }
 44:       if (j < n - 1) {
 45:         J = Ii + 1;
 46:         PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
 47:       }
 48:       v = 4.0;
 49:       PetscCall(MatSetValues(C, 1, &Ii, 1, &Ii, &v, INSERT_VALUES));
 50:     }
 51:   }
 52:   PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
 53:   PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
 54:   PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD, PETSC_VIEWER_ASCII_INFO));
 55:   PetscCall(MatView(C, PETSC_VIEWER_STDOUT_WORLD));
 56:   PetscCall(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD));
 57:   PetscCall(MatView(C, PETSC_VIEWER_STDOUT_WORLD));

 59:   PetscCall(MatGetOwnershipRange(C, &rstart, &rend));
 60:   for (i = rstart; i < rend; i++) {
 61:     PetscCall(MatGetRow(C, i, &nz, &idx, &values));
 62:     PetscCall(PetscSynchronizedFPrintf(PETSC_COMM_WORLD, stdout, "[%d] get row %" PetscInt_FMT ": ", rank, i));
 63:     for (j = 0; j < nz; j++) PetscCall(PetscSynchronizedFPrintf(PETSC_COMM_WORLD, stdout, "%" PetscInt_FMT " %g  ", idx[j], (double)PetscRealPart(values[j])));
 64:     PetscCall(PetscSynchronizedFPrintf(PETSC_COMM_WORLD, stdout, "\n"));
 65:     PetscCall(MatRestoreRow(C, i, &nz, &idx, &values));
 66:   }
 67:   PetscCall(PetscSynchronizedFlush(PETSC_COMM_WORLD, stdout));

 69:   PetscCall(MatConvert(C, MATSAME, MAT_INITIAL_MATRIX, &A));
 70:   PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD, PETSC_VIEWER_ASCII_INFO));
 71:   PetscCall(MatView(A, PETSC_VIEWER_STDOUT_WORLD));
 72:   PetscCall(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD));
 73:   PetscCall(MatView(A, PETSC_VIEWER_STDOUT_WORLD));

 75:   PetscCall(MatDestroy(&A));
 76:   PetscCall(MatDestroy(&C));
 77:   PetscCall(PetscFinalize());
 78:   return 0;
 79: }

 81: /*TEST

 83:    test:
 84:       args: -mat_type seqaij

 86: TEST*/