Actual source code: ex20.c

  1: static char help[] = "Tests converting a matrix to another format with MatConvert().\n\n";

  3: #include <petscmat.h>

  5: int main(int argc, char **args)
  6: {
  7:   Mat         C, A;
  8:   PetscInt    i, j, m = 5, n = 4, Ii, J;
  9:   PetscMPIInt rank, size;
 10:   PetscScalar v;
 11:   char        mtype[256];

 13:   PetscFunctionBeginUser;
 14:   PetscCall(PetscInitialize(&argc, &args, NULL, help));
 15:   PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));

 17:   /* This example does not work correctly for np > 2 */
 18:   PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
 19:   PetscCheck(size <= 2, PETSC_COMM_WORLD, PETSC_ERR_WRONG_MPI_SIZE, "Use np <= 2");

 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(MatSetUp(C));
 26:   for (i = 0; i < m; i++) {
 27:     for (j = 2 * rank; j < 2 * rank + 2; j++) {
 28:       v  = -1.0;
 29:       Ii = j + n * i;
 30:       if (i > 0) {
 31:         J = Ii - n;
 32:         PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
 33:       }
 34:       if (i < m - 1) {
 35:         J = Ii + n;
 36:         PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
 37:       }
 38:       if (j > 0) {
 39:         J = Ii - 1;
 40:         PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
 41:       }
 42:       if (j < n - 1) {
 43:         J = Ii + 1;
 44:         PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
 45:       }
 46:       v = 4.0;
 47:       PetscCall(MatSetValues(C, 1, &Ii, 1, &Ii, &v, INSERT_VALUES));
 48:     }
 49:   }

 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(PetscStrncpy(mtype, MATSAME, sizeof(mtype)));
 59:   PetscCall(PetscOptionsGetString(NULL, NULL, "-conv_mat_type", mtype, sizeof(mtype), NULL));
 60:   PetscCall(MatConvert(C, mtype, MAT_INITIAL_MATRIX, &A));
 61:   PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD, PETSC_VIEWER_ASCII_INFO));
 62:   PetscCall(MatView(A, PETSC_VIEWER_STDOUT_WORLD));
 63:   PetscCall(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD));
 64:   PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD, PETSC_VIEWER_ASCII_IMPL));
 65:   PetscCall(MatView(A, PETSC_VIEWER_STDOUT_WORLD));
 66:   PetscCall(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD));

 68:   /* Free data structures */
 69:   PetscCall(MatDestroy(&A));
 70:   PetscCall(MatDestroy(&C));

 72:   PetscCall(PetscFinalize());
 73:   return 0;
 74: }

 76: /*TEST

 78:    test:
 79:       args: -conv_mat_type seqaij

 81: TEST*/