Actual source code: ex11.c
2: static char help[] = "Scatters from a parallel vector to a sequential vector.\n\n";
4: #include petscvec.h
5: #include petscsys.h
9: int main(int argc,char **argv)
10: {
12: PetscMPIInt size,rank;
13: PetscInt i,N;
14: PetscScalar value;
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: VecCreate(PETSC_COMM_WORLD,&x);
25: VecSetSizes(x,rank+1,PETSC_DECIDE);
26: VecSetFromOptions(x);
27: VecGetSize(x,&N);
28: VecCreateSeq(PETSC_COMM_SELF,N-rank,&y);
30: /* create two index sets */
31: ISCreateStride(PETSC_COMM_SELF,N-rank,rank,1,&is1);
32: ISCreateStride(PETSC_COMM_SELF,N-rank,0,1,&is2);
34: /* fill parallel vector: note this is not efficient way*/
35: for (i=0; i<N; i++) {
36: value = (PetscScalar) i;
37: VecSetValues(x,1,&i,&value,INSERT_VALUES);
38: }
39: VecAssemblyBegin(x);
40: VecAssemblyEnd(x);
41: VecSet(y,-1.0);
43: VecView(x,PETSC_VIEWER_STDOUT_WORLD);
45: VecScatterCreate(x,is1,y,is2,&ctx);
46: VecScatterBegin(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
47: VecScatterEnd(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
48: VecScatterDestroy(ctx);
50: if (!rank)
51: {printf("----\n"); VecView(y,PETSC_VIEWER_STDOUT_SELF);}
53: ISDestroy(is1);
54: ISDestroy(is2);
55: VecDestroy(x);
56: VecDestroy(y);
58: PetscFinalize();
59: return 0;
60: }
61: