Actual source code: ex24.c
2: static char help[] = "Scatters from a parallel vector to a sequential vector.\n\
3: Tests where the local part of the scatter is a copy.\n\n";
5: #include petscvec.h
6: #include petscsys.h
10: int main(int argc,char **argv)
11: {
13: PetscMPIInt size,rank;
14: PetscInt n = 5,i,*blks,bs = 1,m = 2;
15: PetscScalar value;
16: Vec x,y;
17: IS is1,is2;
18: VecScatter ctx = 0;
19: PetscViewer sviewer;
21: PetscInitialize(&argc,&argv,(char*)0,help);
23: PetscOptionsGetInt(PETSC_NULL,"-n",&n,PETSC_NULL);
24: PetscOptionsGetInt(PETSC_NULL,"-bs",&bs,PETSC_NULL);
26: MPI_Comm_size(PETSC_COMM_WORLD,&size);
27: MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
29: /* create two vectors */
30: VecCreate(PETSC_COMM_WORLD,&x);
31: VecSetSizes(x,PETSC_DECIDE,size*bs*n);
32: VecSetFromOptions(x);
34: /* create two index sets */
35: if (rank < size-1) {
36: m = n + 2;
37: } else {
38: m = n;
39: }
40: PetscMalloc((m)*sizeof(PetscInt),&blks);
41: blks[0] = n*rank*bs;
42: for (i=1; i<m; i++) {
43: blks[i] = blks[i-1] + bs;
44: }
45: ISCreateBlock(PETSC_COMM_SELF,bs,m,blks,&is1);
46: PetscFree(blks);
48: VecCreateSeq(PETSC_COMM_SELF,bs*m,&y);
49: ISCreateStride(PETSC_COMM_SELF,bs*m,0,1,&is2);
51: /* each processor inserts the entire vector */
52: /* this is redundant but tests assembly */
53: for (i=0; i<bs*n*size; i++) {
54: value = (PetscScalar) i;
55: VecSetValues(x,1,&i,&value,INSERT_VALUES);
56: }
57: VecAssemblyBegin(x);
58: VecAssemblyEnd(x);
59: VecView(x,PETSC_VIEWER_STDOUT_WORLD);
61: VecScatterCreate(x,is1,y,is2,&ctx);
62: VecScatterBegin(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
63: VecScatterEnd(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
65: PetscSynchronizedPrintf(PETSC_COMM_WORLD,"----\n");
66: PetscViewerGetSingleton(PETSC_VIEWER_STDOUT_WORLD,&sviewer);
67: VecView(y,sviewer); fflush(stdout);
68: PetscViewerRestoreSingleton(PETSC_VIEWER_STDOUT_WORLD,&sviewer);
69: PetscSynchronizedFlush(PETSC_COMM_WORLD);
71: VecScatterDestroy(ctx);
73: VecDestroy(x);
74: VecDestroy(y);
75: ISDestroy(is1);
76: ISDestroy(is2);
78: PetscFinalize();
79: return 0;
80: }
81: