Actual source code: ex14.c
petsc-3.12.1 2019-10-22
2: static char help[] = "Scatters from a sequential vector to a parallel vector.\n\
3: This does the tricky case.\n\n";
5: #include <petscvec.h>
7: int main(int argc,char **argv)
8: {
10: PetscInt n = 5,N;
11: PetscMPIInt size,rank;
12: PetscScalar value,zero = 0.0;
13: Vec x,y;
14: IS is1,is2;
15: VecScatter ctx = 0;
17: PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
18: MPI_Comm_size(PETSC_COMM_WORLD,&size);
19: MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
21: /* create two vectors */
22: N = size*n;
23: VecCreate(PETSC_COMM_WORLD,&y);
24: VecSetSizes(y,PETSC_DECIDE,N);
25: VecSetFromOptions(y);
26: VecCreateSeq(PETSC_COMM_SELF,N,&x);
28: /* create two index sets */
29: ISCreateStride(PETSC_COMM_SELF,n,0,1,&is1);
30: ISCreateStride(PETSC_COMM_SELF,n,rank,1,&is2);
32: value = rank+1;
33: VecSet(x,value);
34: VecSet(y,zero);
36: VecScatterCreate(x,is1,y,is2,&ctx);
37: VecScatterBegin(ctx,x,y,ADD_VALUES,SCATTER_FORWARD);
38: VecScatterEnd(ctx,x,y,ADD_VALUES,SCATTER_FORWARD);
39: VecScatterDestroy(&ctx);
41: VecView(y,PETSC_VIEWER_STDOUT_WORLD);
43: VecDestroy(&x);
44: VecDestroy(&y);
45: ISDestroy(&is1);
46: ISDestroy(&is2);
48: PetscFinalize();
49: return ierr;
50: }
54: /*TEST
56: test:
57: nsize: 2
59: TEST*/