Actual source code: ex10.c
2: static char help[]= "Scatters from a parallel vector to a sequential vector.\n\
3: uses block index sets\n\n";
5: #include <petscvec.h>
7: int main(int argc,char **argv)
8: {
9: PetscInt bs = 1,n = 5,ix0[3] = {5,7,9},ix1[3] = {2,3,4},i,iy0[3] = {1,2,4},iy1[3] = {0,1,3};
10: PetscMPIInt size,rank;
11: PetscScalar value;
12: Vec x,y;
13: IS isx,isy;
14: VecScatter ctx = 0,newctx;
16: PetscInitialize(&argc,&argv,(char*)0,help);
17: MPI_Comm_size(PETSC_COMM_WORLD,&size);
18: MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
22: PetscOptionsGetInt(NULL,NULL,"-bs",&bs,NULL);
23: n = bs*n;
25: /* create two vectors */
26: VecCreate(PETSC_COMM_WORLD,&x);
27: VecSetSizes(x,PETSC_DECIDE,size*n);
28: VecSetFromOptions(x);
29: VecCreateSeq(PETSC_COMM_SELF,n,&y);
31: /* create two index sets */
32: if (rank == 0) {
33: ISCreateBlock(PETSC_COMM_SELF,bs,3,ix0,PETSC_COPY_VALUES,&isx);
34: ISCreateBlock(PETSC_COMM_SELF,bs,3,iy0,PETSC_COPY_VALUES,&isy);
35: } else {
36: ISCreateBlock(PETSC_COMM_SELF,bs,3,ix1,PETSC_COPY_VALUES,&isx);
37: ISCreateBlock(PETSC_COMM_SELF,bs,3,iy1,PETSC_COPY_VALUES,&isy);
38: }
40: /* fill local part of parallel vector */
41: for (i=n*rank; i<n*(rank+1); i++) {
42: value = (PetscScalar) i;
43: VecSetValues(x,1,&i,&value,INSERT_VALUES);
44: }
45: VecAssemblyBegin(x);
46: VecAssemblyEnd(x);
48: VecView(x,PETSC_VIEWER_STDOUT_WORLD);
50: /* fill local part of parallel vector */
51: for (i=0; i<n; i++) {
52: value = -(PetscScalar) (i + 100*rank);
53: VecSetValues(y,1,&i,&value,INSERT_VALUES);
54: }
55: VecAssemblyBegin(y);
56: VecAssemblyEnd(y);
58: VecScatterCreate(x,isx,y,isy,&ctx);
59: VecScatterCopy(ctx,&newctx);
60: VecScatterDestroy(&ctx);
62: VecScatterBegin(newctx,y,x,INSERT_VALUES,SCATTER_REVERSE);
63: VecScatterEnd(newctx,y,x,INSERT_VALUES,SCATTER_REVERSE);
64: VecScatterDestroy(&newctx);
66: VecView(x,PETSC_VIEWER_STDOUT_WORLD);
68: ISDestroy(&isx);
69: ISDestroy(&isy);
70: VecDestroy(&x);
71: VecDestroy(&y);
73: PetscFinalize();
74: return 0;
75: }
77: /*TEST
79: test:
80: nsize: 2
82: TEST*/