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>
7: int main(int argc,char **argv)
8: {
9: PetscInt n = 5,N;
10: PetscMPIInt size,rank;
11: PetscScalar value,zero = 0.0;
12: Vec x,y;
13: IS is1,is2;
14: VecScatter ctx = 0;
16: PetscInitialize(&argc,&argv,(char*)0,help);
17: MPI_Comm_size(PETSC_COMM_WORLD,&size);
18: MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
20: /* create two vectors */
21: N = size*n;
22: VecCreate(PETSC_COMM_WORLD,&y);
23: VecSetSizes(y,PETSC_DECIDE,N);
24: VecSetFromOptions(y);
25: VecCreateSeq(PETSC_COMM_SELF,N,&x);
27: /* create two index sets */
28: ISCreateStride(PETSC_COMM_SELF,n,0,1,&is1);
29: ISCreateStride(PETSC_COMM_SELF,n,rank,1,&is2);
31: value = rank+1;
32: VecSet(x,value);
33: VecSet(y,zero);
35: VecScatterCreate(x,is1,y,is2,&ctx);
36: VecScatterBegin(ctx,x,y,ADD_VALUES,SCATTER_FORWARD);
37: VecScatterEnd(ctx,x,y,ADD_VALUES,SCATTER_FORWARD);
38: VecScatterDestroy(&ctx);
40: VecView(y,PETSC_VIEWER_STDOUT_WORLD);
42: VecDestroy(&x);
43: VecDestroy(&y);
44: ISDestroy(&is1);
45: ISDestroy(&is2);
47: PetscFinalize();
48: return 0;
49: }
51: /*TEST
53: test:
54: nsize: 2
56: TEST*/