Actual source code: ex14.c
2: static char help[] = "Scatters from a sequential vector to a parallel vector.\n\
3: This does the tricky case.\n\n";
5: #include petscvec.h
9: int main(int argc,char **argv)
10: {
12: PetscInt n = 5,N;
13: PetscMPIInt size,rank;
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: VecCreateSeq(PETSC_COMM_SELF,N,&x);
30: /* create two index sets */
31: ISCreateStride(PETSC_COMM_SELF,n,0,1,&is1);
32: ISCreateStride(PETSC_COMM_SELF,n,rank,1,&is2);
34: value = rank+1;
35: VecSet(x,value);
36: VecSet(y,zero);
38: VecScatterCreate(x,is1,y,is2,&ctx);
39: VecScatterBegin(ctx,x,y,ADD_VALUES,SCATTER_FORWARD);
40: VecScatterEnd(ctx,x,y,ADD_VALUES,SCATTER_FORWARD);
41: VecScatterDestroy(ctx);
42:
43: VecView(y,PETSC_VIEWER_STDOUT_WORLD);
45: VecDestroy(x);
46: VecDestroy(y);
47: ISDestroy(is1);
48: ISDestroy(is2);
50: PetscFinalize();
51: return 0;
52: }
53: