Actual source code: ex11.c
1: /*$Id: ex11.c,v 1.52 2001/09/11 16:32:10 bsmith Exp $*/
3: static char help[] = "Scatters from a parallel vector to a sequential vector.nn";
5: #include petscvec.h
6: #include petscsys.h
8: int main(int argc,char **argv)
9: {
10: int ierr,size,rank,i,N;
11: PetscScalar mone = -1.0,value;
12: Vec x,y;
13: IS is1,is2;
14: VecScatter ctx = 0;
16: PetscInitialize(&argc,&argv,(char*)0,help);
17: MPI_Comm_size(PETSC_COMM_WORLD,&size);
18: MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
20: /* create two vectors */
21: VecCreate(PETSC_COMM_WORLD,&x);
22: VecSetSizes(x,rank+1,PETSC_DECIDE);
23: VecSetFromOptions(x);
24: VecGetSize(x,&N);
25: VecCreateSeq(PETSC_COMM_SELF,N-rank,&y);
27: /* create two index sets */
28: ISCreateStride(PETSC_COMM_SELF,N-rank,rank,1,&is1);
29: ISCreateStride(PETSC_COMM_SELF,N-rank,0,1,&is2);
31: /* fill parallel vector: note this is not efficient way*/
32: for (i=0; i<N; i++) {
33: value = (PetscScalar) i;
34: VecSetValues(x,1,&i,&value,INSERT_VALUES);
35: }
36: VecAssemblyBegin(x);
37: VecAssemblyEnd(x);
38: VecSet(&mone,y);
40: VecView(x,PETSC_VIEWER_STDOUT_WORLD);
42: VecScatterCreate(x,is1,y,is2,&ctx);
43: VecScatterBegin(x,y,INSERT_VALUES,SCATTER_FORWARD,ctx);
44: VecScatterEnd(x,y,INSERT_VALUES,SCATTER_FORWARD,ctx);
45: VecScatterDestroy(ctx);
47: if (!rank)
48: {printf("----n"); VecView(y,PETSC_VIEWER_STDOUT_SELF);}
50: ISDestroy(is1);
51: ISDestroy(is2);
52: VecDestroy(x);
53: VecDestroy(y);
55: PetscFinalize();
56: return 0;
57: }
58: