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:   
 10:   PetscInt       n = 3,i;
 11:   PetscReal      *la_nodes,*la_weights,*n_nodes,*n_weights;

 13:   PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
 14:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);

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

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

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

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

 43:   PetscFinalize();
 44:   return ierr;
 45: }

 47: /*TEST

 49:    test:

 51: TEST*/