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>
8: int main(int argc,char **argv)
9: {
10: PetscMPIInt size,rank;
11: PetscInt n = 5,i;
12: PetscScalar value;
13: Vec x,y;
14: IS is1,is2;
15: VecScatter ctx = 0;
17: 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,PETSC_DECIDE,size*n);
25: VecSetFromOptions(x);
26: VecCreateSeq(PETSC_COMM_SELF,n,&y);
28: /* create two index sets */
29: ISCreateStride(PETSC_COMM_SELF,n,n*rank,1,&is1);
30: ISCreateStride(PETSC_COMM_SELF,n,0,1,&is2);
32: /* each processor inserts the entire vector */
33: /* this is redundant but tests assembly */
34: for (i=0; i<n; i++) {
35: value = (PetscScalar) (i + 10*rank);
36: VecSetValues(y,1,&i,&value,INSERT_VALUES);
37: }
38: VecAssemblyBegin(y);
39: VecAssemblyEnd(y);
41: VecScatterCreate(y,is2,x,is1,&ctx);
42: VecScatterBegin(ctx,y,x,INSERT_VALUES,SCATTER_FORWARD);
43: VecScatterEnd(ctx,y,x,INSERT_VALUES,SCATTER_FORWARD);
44: VecScatterDestroy(&ctx);
46: VecView(x,PETSC_VIEWER_STDOUT_WORLD);
48: VecDestroy(&x);
49: VecDestroy(&y);
50: ISDestroy(&is1);
51: ISDestroy(&is2);
53: PetscFinalize();
54: return 0;
55: }
57: /*TEST
59: test:
60: nsize: 2
62: TEST*/