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: {

  9:   PetscInt       n = 3,i;
 10:   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*/