Actual source code: ex10.c
petsc-3.3-p6 2013-02-11
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>
9: int main(int argc,char **argv)
10: {
12: 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};
13: PetscMPIInt size,rank;
14: PetscScalar value;
15: Vec x,y;
16: IS isx,isy;
17: VecScatter ctx = 0,newctx;
19: PetscInitialize(&argc,&argv,(char*)0,help);
20: MPI_Comm_size(PETSC_COMM_WORLD,&size);
21: MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
23: if (size != 2) SETERRQ(PETSC_COMM_SELF,1,"Must run with 2 processors");
25: PetscOptionsGetInt(PETSC_NULL,"-bs",&bs,PETSC_NULL);
26: n = bs*n;
28: /* create two vectors */
29: VecCreate(PETSC_COMM_WORLD,&x);
30: VecSetSizes(x,PETSC_DECIDE,size*n);
31: VecSetFromOptions(x);
32: VecCreateSeq(PETSC_COMM_SELF,n,&y);
34: /* create two index sets */
35: if (!rank) {
36: ISCreateBlock(PETSC_COMM_SELF,bs,3,ix0,PETSC_COPY_VALUES,&isx);
37: ISCreateBlock(PETSC_COMM_SELF,bs,3,iy0,PETSC_COPY_VALUES,&isy);
38: } else {
39: ISCreateBlock(PETSC_COMM_SELF,bs,3,ix1,PETSC_COPY_VALUES,&isx);
40: ISCreateBlock(PETSC_COMM_SELF,bs,3,iy1,PETSC_COPY_VALUES,&isy);
41: }
43: /* fill local part of parallel vector */
44: for (i=n*rank; i<n*(rank+1); i++) {
45: value = (PetscScalar) i;
46: VecSetValues(x,1,&i,&value,INSERT_VALUES);
47: }
48: VecAssemblyBegin(x);
49: VecAssemblyEnd(x);
51: VecView(x,PETSC_VIEWER_STDOUT_WORLD);
53: /* fill local part of parallel vector */
54: for (i=0; i<n; i++) {
55: value = -(PetscScalar) (i + 100*rank);
56: VecSetValues(y,1,&i,&value,INSERT_VALUES);
57: }
58: VecAssemblyBegin(y);
59: VecAssemblyEnd(y);
62: VecScatterCreate(x,isx,y,isy,&ctx);
63: VecScatterCopy(ctx,&newctx);
64: VecScatterDestroy(&ctx);
66: VecScatterBegin(newctx,y,x,INSERT_VALUES,SCATTER_REVERSE);
67: VecScatterEnd(newctx,y,x,INSERT_VALUES,SCATTER_REVERSE);
68: VecScatterDestroy(&newctx);
70: VecView(x,PETSC_VIEWER_STDOUT_WORLD);
72: ISDestroy(&isx);
73: ISDestroy(&isy);
74: VecDestroy(&x);
75: VecDestroy(&y);
77: PetscFinalize();
78: return 0;
79: }
80: