Actual source code: ex20.c


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

  4: #include <petscmat.h>

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

 14:   PetscFunctionBeginUser;
 15:   PetscCall(PetscInitialize(&argc, &args, (char *)0, help));
 16:   PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));

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

 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(MatSetUp(C));
 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:   }

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

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

 73:   PetscCall(PetscFinalize());
 74:   return 0;
 75: }

 77: /*TEST

 79:    test:
 80:       args: -conv_mat_type seqaij

 82: TEST*/