xref: /petsc/src/dm/dt/tests/ex2.c (revision 732aec7a18f2199fb53bb9a2f3aef439a834ce31)
1 static char help[] = "Tests 1D cell-based discretization tools.\n\n";
2 
3 #include <petscdt.h>
4 #include <petscviewer.h>
5 
main(int argc,char ** argv)6 int main(int argc, char **argv)
7 {
8   PetscInt  i, j, degrees[1000], ndegrees, nsrc_points, ntarget_points;
9   PetscReal src_points[1000], target_points[1000], *R;
10   PetscBool flg;
11 
12   PetscFunctionBeginUser;
13   PetscCall(PetscInitialize(&argc, &argv, NULL, help));
14   PetscOptionsBegin(PETSC_COMM_WORLD, NULL, "Discretization tools test options", NULL);
15   {
16     ndegrees   = 1000;
17     degrees[0] = 1;
18     degrees[1] = 2;
19     degrees[2] = 3;
20     PetscCall(PetscOptionsIntArray("-degrees", "list of max degrees to evaluate", "", degrees, &ndegrees, &flg));
21     if (!flg) ndegrees = 3;
22 
23     nsrc_points   = 1000;
24     src_points[0] = -1.;
25     src_points[1] = 0.;
26     src_points[2] = 1.;
27     PetscCall(PetscOptionsRealArray("-src_points", "list of points defining intervals on which to integrate", "", src_points, &nsrc_points, &flg));
28     if (!flg) nsrc_points = 3;
29 
30     ntarget_points   = 1000;
31     target_points[0] = -1.;
32     target_points[1] = 0.;
33     target_points[2] = 1.;
34     PetscCall(PetscOptionsRealArray("-target_points", "list of points defining intervals on which to integrate", "", target_points, &ntarget_points, &flg));
35     if (!flg) ntarget_points = 3;
36   }
37   PetscOptionsEnd();
38 
39   PetscCall(PetscMalloc1((nsrc_points - 1) * (ntarget_points - 1), &R));
40   for (i = 0; i < ndegrees; i++) {
41     PetscCall(PetscDTReconstructPoly(degrees[i], nsrc_points - 1, src_points, ntarget_points - 1, target_points, R));
42     for (j = 0; j < (ntarget_points - 1) * (nsrc_points - 1); j++) { /* Truncate to zero for nicer output */
43       if (PetscAbs(R[j]) < 10 * PETSC_MACHINE_EPSILON) R[j] = 0;
44     }
45     for (j = 0; j < ntarget_points - 1; j++) {
46       PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Degree %" PetscInt_FMT " target interval (%g,%g)\n", degrees[i], (double)target_points[j], (double)target_points[j + 1]));
47       PetscCall(PetscRealView(nsrc_points - 1, R + j * (nsrc_points - 1), PETSC_VIEWER_STDOUT_WORLD));
48     }
49   }
50   PetscCall(PetscFree(R));
51   PetscCall(PetscFinalize());
52   return 0;
53 }
54 
55 /*TEST
56   test:
57     suffix: 1
58     args: -degrees 1,2,3 -target_points -0.3,0,.2 -src_points -1,-.3,0,.2,1
59 TEST*/
60