Actual source code: ex22.c
petsc-3.12.0 2019-09-29
2: static char help[] = "Scatters from a parallel vector to a parallel vector.\n\n";
4: #include <petscvec.h>
6: int main(int argc,char **argv)
7: {
9: PetscInt n = 5,N,i;
10: PetscMPIInt size,rank;
11: PetscScalar value,zero = 0.0;
12: Vec x,y;
13: IS is1,is2;
14: VecScatter ctx = 0;
16: PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
17: MPI_Comm_size(PETSC_COMM_WORLD,&size);
18: MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
20: /* create two vectors */
21: N = size*n;
22: VecCreate(PETSC_COMM_WORLD,&y);
23: VecSetSizes(y,n,PETSC_DECIDE);
24: VecSetFromOptions(y);
26: VecCreate(PETSC_COMM_WORLD,&x);
27: VecSetSizes(x,n,PETSC_DECIDE);
28: VecSetFromOptions(x);
30: /* create two index sets */
31: ISCreateStride(PETSC_COMM_WORLD,n,n*rank,1,&is1);
32: ISCreateStride(PETSC_COMM_WORLD,n,(n*(rank+1))%N,1,&is2);
34: /* fill local part of parallel vector x */
35: value = (PetscScalar)(rank+1);
36: for (i=n*rank; i<n*(rank+1); i++) {
37: VecSetValues(x,1,&i,&value,INSERT_VALUES);
38: }
39: VecAssemblyBegin(x);
40: VecAssemblyEnd(x);
42: VecSet(y,zero);
44: VecScatterCreate(x,is1,y,is2,&ctx);
45: VecScatterBegin(ctx,x,y,ADD_VALUES,SCATTER_FORWARD);
46: VecScatterEnd(ctx,x,y,ADD_VALUES,SCATTER_FORWARD);
47: VecScatterDestroy(&ctx);
49: VecView(y,PETSC_VIEWER_STDOUT_WORLD);
51: VecDestroy(&x);
52: VecDestroy(&y);
53: ISDestroy(&is1);
54: ISDestroy(&is2);
56: PetscFinalize();
57: return ierr;
58: }
62: /*TEST
64: testset:
65: nsize: 4
66: output_file: output/ex22_1.out
67: filter: grep -v " type:"
68: test:
69: suffix: standard
70: args: -vec_type standard
71: test:
72: requires: cuda
73: suffix: cuda
74: args: -vec_type cuda
75: test:
76: requires: cuda
77: suffix: cuda_sf
78: args: -vec_type cuda -vecscatter_type sf
79: test:
80: requires: viennacl
81: suffix: viennacl
82: args: -vec_type viennacl
84: TEST*/