Actual source code: ex14.c
1: /*$Id: ex14.c,v 1.49 2001/09/11 16:32:10 bsmith Exp $*/
3: static char help[] = "Scatters from a sequential vector to a parallel vector.n
4: This does the tricky case.nn";
6: #include petscvec.h
7: #include petscsys.h
9: int main(int argc,char **argv)
10: {
11: int n = 5,ierr;
12: int size,rank,N;
13: PetscScalar value,zero = 0.0;
14: Vec x,y;
15: IS is1,is2;
16: VecScatter ctx = 0;
18: PetscInitialize(&argc,&argv,(char*)0,help);
19: MPI_Comm_size(PETSC_COMM_WORLD,&size);
20: MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
22: /* create two vectors */
23: N = size*n;
24: VecCreate(PETSC_COMM_WORLD,&y);
25: VecSetSizes(y,PETSC_DECIDE,N);
26: VecSetFromOptions(y);
27: VecCreateSeq(PETSC_COMM_SELF,N,&x);
29: /* create two index sets */
30: ISCreateStride(PETSC_COMM_SELF,n,0,1,&is1);
31: ISCreateStride(PETSC_COMM_SELF,n,rank,1,&is2);
33: value = rank+1;
34: VecSet(&value,x);
35: VecSet(&zero,y);
37: VecScatterCreate(x,is1,y,is2,&ctx);
38: VecScatterBegin(x,y,ADD_VALUES,SCATTER_FORWARD,ctx);
39: VecScatterEnd(x,y,ADD_VALUES,SCATTER_FORWARD,ctx);
40: VecScatterDestroy(ctx);
41:
42: VecView(y,PETSC_VIEWER_STDOUT_WORLD);
44: VecDestroy(x);
45: VecDestroy(y);
46: ISDestroy(is1);
47: ISDestroy(is2);
49: PetscFinalize();
50: return 0;
51: }
52: