Actual source code: ex11.c
2: static char help[] = "Scatters from a parallel vector to a sequential vector.\n\n";
4: #include petscvec.h
8: int main(int argc,char **argv)
9: {
11: PetscMPIInt size,rank;
12: PetscInt i,N;
13: PetscScalar value;
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: VecCreate(PETSC_COMM_WORLD,&x);
24: VecSetSizes(x,rank+1,PETSC_DECIDE);
25: VecSetFromOptions(x);
26: VecGetSize(x,&N);
27: VecCreateSeq(PETSC_COMM_SELF,N-rank,&y);
29: /* create two index sets */
30: ISCreateStride(PETSC_COMM_SELF,N-rank,rank,1,&is1);
31: ISCreateStride(PETSC_COMM_SELF,N-rank,0,1,&is2);
33: /* fill parallel vector: note this is not efficient way*/
34: for (i=0; i<N; i++) {
35: value = (PetscScalar) i;
36: VecSetValues(x,1,&i,&value,INSERT_VALUES);
37: }
38: VecAssemblyBegin(x);
39: VecAssemblyEnd(x);
40: VecSet(y,-1.0);
42: VecView(x,PETSC_VIEWER_STDOUT_WORLD);
44: VecScatterCreate(x,is1,y,is2,&ctx);
45: VecScatterBegin(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
46: VecScatterEnd(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
47: VecScatterDestroy(ctx);
49: if (!rank)
50: {printf("----\n"); VecView(y,PETSC_VIEWER_STDOUT_SELF);}
52: ISDestroy(is1);
53: ISDestroy(is2);
54: VecDestroy(x);
55: VecDestroy(y);
57: PetscFinalize();
58: return 0;
59: }
60: