Actual source code: ex21.c

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

  4: #include <petscmat.h>

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

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

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

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

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

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

 80: /*TEST

 82:    test:
 83:       args: -mat_type seqaij

 85: TEST*/