Actual source code: ex12f.F90
1: program main
3: #include <petsc/finclude/petscvec.h>
5: use petscvec
6: implicit none
8: PetscErrorCode ierr
9: Vec v,s
10: PetscInt,parameter :: n = 20
11: PetscScalar,parameter :: sone = 1.0
12: PetscBool :: flg
13: PetscInt,parameter :: zero = 0, one = 1, two = 2
15: call PetscInitialize(PETSC_NULL_CHARACTER,ierr)
16: if (ierr /= 0) then
17: print*,'PetscInitialize failed'
18: stop
19: endif
21: call PetscOptionsGetInt(PETSC_NULL_OPTIONS,PETSC_NULL_CHARACTER,"-n",n,flg,ierr);CHKERRA(ierr)
23: ! Create multi-component vector with 2 components
24: call VecCreate(PETSC_COMM_WORLD,v,ierr);CHKERRA(ierr)
25: call VecSetSizes(v,PETSC_DECIDE,n,ierr);CHKERRA(ierr)
26: call VecSetBlockSize(v,two,ierr);CHKERRA(ierr)
27: call VecSetFromOptions(v,ierr);CHKERRA(ierr)
29: ! Create single-component vector
30: call VecCreate(PETSC_COMM_WORLD,s,ierr);CHKERRA(ierr)
31: call VecSetSizes(s,PETSC_DECIDE,n/2,ierr);CHKERRA(ierr)
32: call VecSetFromOptions(s,ierr);CHKERRA(ierr)
34: !Set the vectors to entries to a constant value.
35: call VecSet(v,sone,ierr);CHKERRA(ierr)
37: !Get the first component from the multi-component vector to the single vector
38: call VecStrideGather(v,zero,s,INSERT_VALUES,ierr);CHKERRA(ierr)
40: call VecView(s,PETSC_VIEWER_STDOUT_WORLD,ierr);CHKERRA(ierr)
42: !Put the values back into the second component
43: call VecStrideScatter(s,one,v,ADD_VALUES,ierr);CHKERRA(ierr)
45: call VecView(v,PETSC_VIEWER_STDOUT_WORLD,ierr);CHKERRA(ierr)
47: ! Free work space.All PETSc objects should be destroyed when they are no longer needed.
48: call VecDestroy(v,ierr);CHKERRA(ierr)
49: call VecDestroy(s,ierr);CHKERRA(ierr)
50: call PetscFinalize(ierr);CHKERRA(ierr)
52: end program
54: !/*TEST
55: !
56: ! test:
57: ! nsize: 2
58: ! output_file: output/ex12_1.out
59: !
60: !TEST*/