Actual source code: ex14.c
1: /*$Id: ex14.c,v 1.49 2001/09/11 16:32:10 bsmith Exp $*/
3: static char help[] = "Scatters from a sequential vector to a parallel vector.\n\
4: This does the tricky case.\n\n";
6: #include petscvec.h
7: #include petscsys.h
11: int main(int argc,char **argv)
12: {
13: int n = 5,ierr;
14: int size,rank,N;
15: PetscScalar value,zero = 0.0;
16: Vec x,y;
17: IS is1,is2;
18: VecScatter ctx = 0;
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,rank,1,&is2);
35: value = rank+1;
36: VecSet(&value,x);
37: VecSet(&zero,y);
39: VecScatterCreate(x,is1,y,is2,&ctx);
40: VecScatterBegin(x,y,ADD_VALUES,SCATTER_FORWARD,ctx);
41: VecScatterEnd(x,y,ADD_VALUES,SCATTER_FORWARD,ctx);
42: VecScatterDestroy(ctx);
43:
44: VecView(y,PETSC_VIEWER_STDOUT_WORLD);
46: VecDestroy(x);
47: VecDestroy(y);
48: ISDestroy(is1);
49: ISDestroy(is2);
51: PetscFinalize();
52: return 0;
53: }
54: