Actual source code: ex17.c
2: static char help[] = "Scatters from a parallel vector to a sequential vector. In\n\
3: this case each local vector is as long as the entire parallel vector.\n\n";
5: #include petscvec.h
6: #include petscsys.h
10: int main(int argc,char **argv)
11: {
13: PetscInt n = 5,N,low,high,iglobal,i;
14: PetscMPIInt size,rank;
15: PetscScalar value,zero = 0.0;
16: Vec x,y;
17: IS is1,is2;
18: VecScatter ctx;
20: PetscInitialize(&argc,&argv,(char*)0,help);
21: MPI_Comm_size(PETSC_COMM_WORLD,&size);
22: MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
24: /* create two vectors */
25: N = size*n;
26: VecCreate(PETSC_COMM_WORLD,&y);
27: VecSetSizes(y,PETSC_DECIDE,N);
28: VecSetFromOptions(y);
29: VecCreateSeq(PETSC_COMM_SELF,N,&x);
31: /* create two index sets */
32: ISCreateStride(PETSC_COMM_SELF,N,0,1,&is1);
33: ISCreateStride(PETSC_COMM_SELF,N,0,1,&is2);
35: VecSet(x,zero);
36: VecGetOwnershipRange(y,&low,&high);
37: for (i=0; i<n; i++) {
38: iglobal = i + low; value = (PetscScalar) (i + 10*rank);
39: VecSetValues(y,1,&iglobal,&value,INSERT_VALUES);
40: }
41: VecAssemblyBegin(y);
42: VecAssemblyEnd(y);
43: VecView(y,PETSC_VIEWER_STDOUT_WORLD);
45: VecScatterCreate(y,is2,x,is1,&ctx);
46: VecScatterBegin(ctx,y,x,ADD_VALUES,SCATTER_FORWARD);
47: VecScatterEnd(ctx,y,x,ADD_VALUES,SCATTER_FORWARD);
48: VecScatterDestroy(ctx);
49:
50: if (!rank)
51: {printf("----\n"); VecView(x,PETSC_VIEWER_STDOUT_SELF);}
53: VecDestroy(x);
54: VecDestroy(y);
55: ISDestroy(is1);
56: ISDestroy(is2);
58: PetscFinalize();
59: return 0;
60: }
61: