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*/