Date: 2025-03-28T21:11:20+00:00

Actual source code: ex3f90.F90

      1: !
      2: !    Description:  Creates an index set based on blocks of integers. Views that index set
      3: !    and then destroys it.
      4: !
      5: !
      6:       program main
      7: #include <petsc/finclude/petscis.h>
      8:       use petscis
      9:       implicit none

     11:       PetscErrorCode ierr
     12:       PetscInt n,bs,issize
     13:       PetscInt inputindices(4)
     14:       PetscInt, pointer :: indices(:)
     15:       IS       set
     16:       PetscBool  isablock;

     18:       n               = 4
     19:       bs              = 3
     20:       inputindices(1) = 0
     21:       inputindices(2) = 1
     22:       inputindices(3) = 3
     23:       inputindices(4) = 4

     25:       PetscCallA(PetscInitialize(ierr))
     26: !
     27: !    Create a block index set. The index set has 4 blocks each of size 3.
     28: !    The indices are {0,1,2,3,4,5,9,10,11,12,13,14}
     29: !    Note each processor is generating its own index set
     30: !    (in this case they are all identical)
     31: !
     32:       PetscCallA(ISCreateBlock(PETSC_COMM_SELF,bs,n,inputindices,PETSC_COPY_VALUES,set,ierr))
     33:       PetscCallA(ISView(set,PETSC_VIEWER_STDOUT_SELF,ierr))

     35: !
     36: !    Extract indices from set.
     37: !
     38:       PetscCallA(ISGetLocalSize(set,issize,ierr))
     39:       PetscCallA(ISGetIndicesF90(set,indices,ierr))
     40:       write(6,100)indices
     41:  100  format(12I3)
     42:       PetscCallA(ISRestoreIndicesF90(set,indices,ierr))

     44: !
     45: !    Extract the block indices. This returns one index per block.
     46: !
     47:       PetscCallA(ISBlockGetIndicesF90(set,indices,ierr))
     48:       write(6,200)indices
     49:  200  format(4I3)
     50:       PetscCallA(ISBlockRestoreIndicesF90(set,indices,ierr))

     52: !
     53: !    Check if this is really a block index set
     54: !
     55:       PetscCallA(PetscObjectTypeCompare(set,ISBLOCK,isablock,ierr))
     56:       if (.not. isablock) then
     57:         write(6,*) 'Index set is not blocked!'
     58:       endif

     60: !
     61: !    Determine the block size of the index set
     62: !
     63:       PetscCallA(ISGetBlockSize(set,bs,ierr))
     64:       if (bs .ne. 3) then
     65:         write(6,*) 'Blocksize != 3'
     66:       endif

     68: !
     69: !    Get the number of blocks
     70: !
     71:       PetscCallA(ISBlockGetLocalSize(set,n,ierr))
     72:       if (n .ne. 4) then
     73:         write(6,*) 'Number of blocks != 4'
     74:       endif

     76:       PetscCallA(ISDestroy(set,ierr))
     77:       PetscCallA(PetscFinalize(ierr))
     78:       end

     80: !/*TEST
     81: !
     82: !   test:
     83: !      filter: sort -b
     84: !      filter_output: sort -b
     85: !
     86: !TEST*/