Actual source code: ex2.c


  2: static char help[] = "Demonstrates creating a stride index set.\n\n";

  4: /*
  5:   Include petscis.h so we can use PETSc IS objects. Note that this automatically
  6:   includes petscsys.h.
  7: */

  9: #include <petscis.h>
 10: #include <petscviewer.h>

 12: int main(int argc,char **argv)
 13: {
 14:   PetscInt       i,n,first,step;
 15:   IS             set;
 16:   const PetscInt *indices;

 18:   PetscInitialize(&argc,&argv,(char*)0,help);

 20:   n     = 10;
 21:   first = 3;
 22:   step  = 2;

 24:   /*
 25:     Create stride index set, starting at 3 with a stride of 2
 26:     Note each processor is generating its own index set
 27:     (in this case they are all identical)
 28:   */
 29:   ISCreateStride(PETSC_COMM_SELF,n,first,step,&set);
 30:   ISView(set,PETSC_VIEWER_STDOUT_SELF);

 32:   /*
 33:     Extract indices from set.
 34:   */
 35:   ISGetIndices(set,&indices);
 36:   PetscPrintf(PETSC_COMM_WORLD,"Printing indices directly\n");
 37:   for (i=0; i<n; i++) {
 38:     PetscPrintf(PETSC_COMM_WORLD,"%" PetscInt_FMT "\n",indices[i]);
 39:   }

 41:   ISRestoreIndices(set,&indices);

 43:   /*
 44:       Determine information on stride
 45:   */
 46:   ISStrideGetInfo(set,&first,&step);
 48:   ISDestroy(&set);
 49:   PetscFinalize();
 50:   return 0;
 51: }

 53: /*TEST

 55:    test:

 57: TEST*/