Actual source code: ex6.c

  1: static char help[] = "Tests 1D Gauss-Lobatto-Legendre discretization on [-1, 1].\n\n";

  3: #include <petscdt.h>
  4: #include <petscviewer.h>

  6: int main(int argc, char **argv)
  7: {
  8:   PetscInt   n = 3, i;
  9:   PetscReal *la_nodes, *la_weights, *n_nodes, *n_weights;

 12:   PetscInitialize(&argc, &argv, (char *)0, help);
 13:   PetscOptionsGetInt(NULL, NULL, "-n", &n, NULL);

 15:   PetscMalloc1(n, &la_nodes);
 16:   PetscMalloc1(n, &la_weights);
 17:   PetscMalloc1(n, &n_nodes);
 18:   PetscMalloc1(n, &n_weights);
 19:   PetscDTGaussLobattoLegendreQuadrature(n, PETSCGAUSSLOBATTOLEGENDRE_VIA_LINEAR_ALGEBRA, la_nodes, la_weights);

 21:   PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_SELF, "Gauss-Lobatto-Legendre nodes and weights computed via linear algebra: \n");
 22:   PetscRealView(n, la_nodes, PETSC_VIEWER_STDOUT_SELF);
 23:   PetscRealView(n, la_weights, PETSC_VIEWER_STDOUT_SELF);
 24:   PetscDTGaussLobattoLegendreQuadrature(n, PETSCGAUSSLOBATTOLEGENDRE_VIA_NEWTON, n_nodes, n_weights);
 25:   PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_SELF, "Gauss-Lobatto-Legendre nodes and weights computed via Newton: \n");
 26:   PetscRealView(n, n_nodes, PETSC_VIEWER_STDOUT_SELF);
 27:   PetscRealView(n, n_weights, PETSC_VIEWER_STDOUT_SELF);

 29:   for (i = 0; i < n; i++) {
 30:     la_nodes[i] -= n_nodes[i];
 31:     la_weights[i] -= n_weights[i];
 32:   }
 33:   PetscViewerASCIIPrintf(PETSC_VIEWER_STDOUT_SELF, "Difference: \n");
 34:   PetscRealView(n, la_nodes, PETSC_VIEWER_STDOUT_SELF);
 35:   PetscRealView(n, la_weights, PETSC_VIEWER_STDOUT_SELF);

 37:   PetscFree(la_nodes);
 38:   PetscFree(la_weights);
 39:   PetscFree(n_nodes);
 40:   PetscFree(n_weights);

 42:   PetscFinalize();
 43:   return 0;
 44: }

 46: /*TEST

 48:    test:

 50: TEST*/