Actual source code: ex4.c

      2: static char help[] = "Demonstrates using ISLocalToGlobalMappings.\n\n";

      4: /*T
      5:     Concepts: local to global mappings
      6:     Concepts: global to local mappings

      8:     Description:  Creates an index set based on blocks of integers. Views that index set
      9:     and then destroys it.
     10: T*/

     14: #include <petscis.h>
     15: #include <petscviewer.h>

     17: int main(int argc,char **argv)
     18: {
     19:   PetscErrorCode         ierr;
     20:   PetscInt               i,n = 4,indices[] = {0,3,9,12},m = 2,input[] = {0,2};
     21:   PetscInt               output[2],inglobals[13],outlocals[13];
     22:   ISLocalToGlobalMapping mapping;

     24:   PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;

     26:   /*
     27:       Create a local to global mapping. Each processor independently
     28:      creates a mapping
     29:   */
     30:   ISLocalToGlobalMappingCreate(PETSC_COMM_WORLD,1,n,indices,PETSC_COPY_VALUES,&mapping);
     31:   ISLocalToGlobalMappingSetFromOptions(mapping);

     33:   /*
     34:      Map a set of local indices to their global values
     35:   */
     36:   ISLocalToGlobalMappingApply(mapping,m,input,output);
     37:   PetscIntView(m,output,PETSC_VIEWER_STDOUT_WORLD);

     39:   /*
     40:      Map some global indices to local, retaining the ones without a local index by -1
     41:   */
     42:   for (i=0; i<13; i++) inglobals[i] = i;
     43:   ISGlobalToLocalMappingApply(mapping,IS_GTOLM_MASK,13,inglobals,NULL,outlocals);
     44:   PetscIntView(13,outlocals,PETSC_VIEWER_STDOUT_WORLD);

     46:   /*
     47:      Map some global indices to local, dropping the ones without a local index.
     48:   */
     49:   ISGlobalToLocalMappingApply(mapping,IS_GTOLM_DROP,13,inglobals,&m,outlocals);
     50:   PetscIntView(m,outlocals,PETSC_VIEWER_STDOUT_WORLD);

     52:   ISLocalToGlobalMappingView(mapping,PETSC_VIEWER_STDOUT_WORLD);
     53:   /*
     54:      Free the space used by the local to global mapping
     55:   */
     56:   ISLocalToGlobalMappingDestroy(&mapping);

     59:   PetscFinalize();
     60:   return ierr;
     61: }

     63: /*TEST

     65:    test:

     67:    test:
     68:       suffix: 2
     69:       args: -islocaltoglobalmapping_type hash

     71: TEST*/