Actual source code: ex5.c
2: static char help[] = "Scatters from a parallel vector to a sequential vector.\n\
3: This does case when we are merely selecting the local part of the\n\
4: parallel vector.\n\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);
18: MPI_Comm_size(PETSC_COMM_WORLD,&size);
19: MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
21: /* create two vectors */
22: VecCreate(PETSC_COMM_WORLD,&x);
23: VecSetSizes(x,PETSC_DECIDE,size*n);
24: VecSetFromOptions(x);
25: VecCreateSeq(PETSC_COMM_SELF,n,&y);
27: /* create two index sets */
28: ISCreateStride(PETSC_COMM_SELF,n,n*rank,1,&is1);
29: ISCreateStride(PETSC_COMM_SELF,n,0,1,&is2);
31: /* each processor inserts the entire vector */
32: /* this is redundant but tests assembly */
33: for (i=0; i<n*size; i++) {
34: value = (PetscScalar) i;
35: VecSetValues(x,1,&i,&value,INSERT_VALUES);
36: }
37: VecAssemblyBegin(x);
38: VecAssemblyEnd(x);
39: VecView(x,PETSC_VIEWER_STDOUT_WORLD);
41: VecScatterCreate(x,is1,y,is2,&ctx);
42: VecScatterBegin(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
43: VecScatterEnd(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
44: VecScatterDestroy(&ctx);
46: if (rank == 0) {
47: PetscPrintf(PETSC_COMM_SELF,"----\n");
48: VecView(y,PETSC_VIEWER_STDOUT_SELF);
49: }
51: VecDestroy(&x);
52: VecDestroy(&y);
53: ISDestroy(&is1);
54: ISDestroy(&is2);
56: PetscFinalize();
57: return 0;
58: }
60: /*TEST
62: test:
63: nsize: 2
65: TEST*/