1: !
  2: !  "$Id: ex1f90.F,v 1.18 2001/01/15 21:44:33 bsmith Exp $";
  3: !
  4: !  Description: Creates an index set based on a set of integers. Views that index set
  5: !  and then destroys it.
  6: !
  7: !/*T
  8: !    Concepts: index sets^manipulating a general index set;
  9: !    Concepts: Fortran90^accessing indices of index set;
 10: !T*/
 11: !
 12: !  The following include statements are required for Fortran programs
 13: !  that use PETSc index sets:
 14: !     petsc.h  - base PETSc routines
 15: !     petscis.h     - index sets (IS objects)
 16: !     petscis.h90   - to allow access to Fortran90 features of index sets
 17: !
 18:       program main
 19:       implicit none

 21:  #include finclude/petsc.h
 22:  #include finclude/petscis.h
 23: #include "finclude/petscis.h90"

 25:       integer ierr,indices(5),rank,n
 26:       integer, pointer :: idx(:)
 27:       IS      is

 29:       call PetscInitialize(PETSC_NULL_CHARACTER,ierr)
 30:       call MPI_Comm_rank(PETSC_COMM_WORLD,rank,ierr)

 32: !  Create an index set with 5 entries. Each processor creates
 33: !  its own index set with its own list of integers.
 34: 
 35:       indices(1) = rank + 1
 36:       indices(2) = rank + 2
 37:       indices(3) = rank + 3
 38:       indices(4) = rank + 4
 39:       indices(5) = rank + 5
 40:       call ISCreateGeneral(PETSC_COMM_SELF,5,indices,is,ierr)

 42: !  Print the index set to stdout

 44:       call ISView(is,PETSC_VIEWER_STDOUT_SELF,ierr)

 46: !  Get the number of indices in the set

 48:       call ISGetLocalSize(is,n,ierr)

 50: !   Get the indices in the index set

 52:       call ISGetIndicesF90(is,idx,ierr)

 54:       if (associated(idx)) then
 55:          write (*,*) 'Association check passed'
 56:       else
 57:          write (*,*) 'Association check failed'
 58:       endif

 60: !   Now any code that needs access to the list of integers
 61: !   has access to it here

 63:       write(6,50) idx
 64:  50   format(5I3)

 66:       write(6,100) rank,idx(1),idx(5)
 67:  100  format('[',i5,'] First index = ',i5,' fifth index = ',i5)
 68: 
 69: !   Once we no longer need access to the indices they should
 70: !   returned to the system

 72:       call ISRestoreIndicesF90(is,idx,ierr)
 73: 
 74: !   All PETSc objects should be destroyed once they are
 75: !   no longer needed

 77:       call ISDestroy(is,ierr)
 78:       call PetscFinalize(ierr)
 79:       end

 81: