Actual source code: ex22.c
1: /*$Id: ex22.c,v 1.24 2001/09/11 16:32:10 bsmith Exp $*/
3: static char help[] = "Scatters from a parallel vector to a parallel vector.\n\n";
5: #include petscvec.h
6: #include petscsys.h
10: int main(int argc,char **argv)
11: {
12: int n = 5,ierr;
13: int size,rank,N;
14: PetscScalar value,zero = 0.0;
15: Vec x,y;
16: IS is1,is2;
17: VecScatter ctx = 0;
19: PetscInitialize(&argc,&argv,(char*)0,help);
20: MPI_Comm_size(PETSC_COMM_WORLD,&size);
21: MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
23: /* create two vectors */
24: N = size*n;
25: VecCreate(PETSC_COMM_WORLD,&y);
26: VecSetSizes(y,PETSC_DECIDE,N);
27: VecSetFromOptions(y);
28: VecCreate(PETSC_COMM_WORLD,&x);
29: VecSetSizes(x,PETSC_DECIDE,N);
30: VecSetFromOptions(x);
31: /* create two index sets */
32: ISCreateStride(PETSC_COMM_WORLD,n,n*rank,1,&is1);
33: ISCreateStride(PETSC_COMM_WORLD,n,(n*(rank+1))%N,1,&is2);
35: value = (PetscScalar)(rank+1);
36: VecSet(&value,x);
37: VecSet(&zero,y);
39: VecScatterCreate(x,is1,y,is2,&ctx);
40: VecScatterBegin(x,y,ADD_VALUES,SCATTER_FORWARD,ctx);
41: VecScatterEnd(x,y,ADD_VALUES,SCATTER_FORWARD,ctx);
42: VecScatterDestroy(ctx);
43:
44: VecView(y,PETSC_VIEWER_STDOUT_WORLD);
46: VecDestroy(x);
47: VecDestroy(y);
48: ISDestroy(is1);
49: ISDestroy(is2);
51: PetscFinalize();
52: return 0;
53: }
54: