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;

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

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

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

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

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

 81: /*TEST

 83:    test:
 84:       args: -mat_type seqaij

 86: TEST*/