Date: 2022-03-31T04:46:33+00:00

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*/

     12: #include <petscis.h>
     13: #include <petscviewer.h>

     15: int main(int argc,char **argv)
     16: {
     17:   PetscInt               i,n = 4,indices[] = {0,3,9,12},m = 2,input[] = {0,2};
     18:   PetscInt               output[2],inglobals[13],outlocals[13];
     19:   ISLocalToGlobalMapping mapping;

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

     23:   /*
     24:       Create a local to global mapping. Each processor independently
     25:      creates a mapping
     26:   */
     27:   ISLocalToGlobalMappingCreate(PETSC_COMM_WORLD,1,n,indices,PETSC_COPY_VALUES,&mapping);
     28:   ISLocalToGlobalMappingSetFromOptions(mapping);

     30:   /*
     31:      Map a set of local indices to their global values
     32:   */
     33:   ISLocalToGlobalMappingApply(mapping,m,input,output);
     34:   PetscIntView(m,output,PETSC_VIEWER_STDOUT_WORLD);

     36:   /*
     37:      Map some global indices to local, retaining the ones without a local index by -1
     38:   */
     39:   for (i=0; i<13; i++) inglobals[i] = i;
     40:   ISGlobalToLocalMappingApply(mapping,IS_GTOLM_MASK,13,inglobals,NULL,outlocals);
     41:   PetscIntView(13,outlocals,PETSC_VIEWER_STDOUT_WORLD);

     43:   /*
     44:      Map some global indices to local, dropping the ones without a local index.
     45:   */
     46:   ISGlobalToLocalMappingApply(mapping,IS_GTOLM_DROP,13,inglobals,&m,outlocals);
     47:   PetscIntView(m,outlocals,PETSC_VIEWER_STDOUT_WORLD);

     49:   ISLocalToGlobalMappingView(mapping,PETSC_VIEWER_STDOUT_WORLD);
     50:   /*
     51:      Free the space used by the local to global mapping
     52:   */
     53:   ISLocalToGlobalMappingDestroy(&mapping);

     55:   PetscFinalize();
     56:   return 0;
     57: }

     59: /*TEST

     61:    test:

     63:    test:
     64:       suffix: 2
     65:       args: -islocaltoglobalmapping_type hash

     67: TEST*/