Actual source code: ex12.c
2: static char help[] = "Scatters from a sequential vector to a parallel vector.\n\
3: This does case when we are merely selecting the local part of the\n\
4: parallel vector.\n";
6: #include petscvec.h
7: #include petscsys.h
11: int main(int argc,char **argv)
12: {
14: PetscMPIInt size,rank;
15: PetscInt n = 5,i;
16: PetscScalar value;
17: Vec x,y;
18: IS is1,is2;
19: VecScatter ctx = 0;
21: PetscInitialize(&argc,&argv,(char*)0,help);
23: MPI_Comm_size(PETSC_COMM_WORLD,&size);
24: MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
26: /* create two vectors */
27: VecCreate(PETSC_COMM_WORLD,&x);
28: VecSetSizes(x,PETSC_DECIDE,size*n);
29: VecSetFromOptions(x);
30: VecCreateSeq(PETSC_COMM_SELF,n,&y);
32: /* create two index sets */
33: ISCreateStride(PETSC_COMM_SELF,n,n*rank,1,&is1);
34: ISCreateStride(PETSC_COMM_SELF,n,0,1,&is2);
36: /* each processor inserts the entire vector */
37: /* this is redundant but tests assembly */
38: for (i=0; i<n; i++) {
39: value = (PetscScalar) (i + 10*rank);
40: VecSetValues(y,1,&i,&value,INSERT_VALUES);
41: }
42: VecAssemblyBegin(y);
43: VecAssemblyEnd(y);
45: VecScatterCreate(y,is2,x,is1,&ctx);
46: VecScatterBegin(ctx,y,x,INSERT_VALUES,SCATTER_FORWARD);
47: VecScatterEnd(ctx,y,x,INSERT_VALUES,SCATTER_FORWARD);
48: VecScatterDestroy(ctx);
49:
50: VecView(x,PETSC_VIEWER_STDOUT_WORLD);
52: VecDestroy(x);
53: VecDestroy(y);
54: ISDestroy(is1);
55: ISDestroy(is2);
57: PetscFinalize();
58: return 0;
59: }
60: