Actual source code: ex24.c
petsc-3.12.0 2019-09-29
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>
7: int main(int argc,char **argv)
8: {
10: PetscMPIInt size,rank;
11: PetscInt n = 5,i,*blks,bs = 1,m = 2;
12: PetscScalar value;
13: Vec x,y;
14: IS is1,is2;
15: VecScatter ctx = 0;
16: PetscViewer sviewer;
18: PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
20: PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
21: PetscOptionsGetInt(NULL,NULL,"-bs",&bs,NULL);
23: MPI_Comm_size(PETSC_COMM_WORLD,&size);
24: MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
26: /* create two vectors */
27: VecCreate(PETSC_COMM_WORLD,&x);
28: VecSetSizes(x,PETSC_DECIDE,size*bs*n);
29: VecSetFromOptions(x);
31: /* create two index sets */
32: if (rank < size-1) m = n + 2;
33: else m = n;
35: PetscMalloc1(m,&blks);
36: blks[0] = n*rank;
37: for (i=1; i<m; i++) blks[i] = blks[i-1] + 1;
38: ISCreateBlock(PETSC_COMM_SELF,bs,m,blks,PETSC_COPY_VALUES,&is1);
39: PetscFree(blks);
41: VecCreateSeq(PETSC_COMM_SELF,bs*m,&y);
42: ISCreateStride(PETSC_COMM_SELF,bs*m,0,1,&is2);
44: /* each processor inserts the entire vector */
45: /* this is redundant but tests assembly */
46: for (i=0; i<bs*n*size; i++) {
47: value = (PetscScalar) i;
48: VecSetValues(x,1,&i,&value,INSERT_VALUES);
49: }
50: VecAssemblyBegin(x);
51: VecAssemblyEnd(x);
52: VecView(x,PETSC_VIEWER_STDOUT_WORLD);
54: VecScatterCreate(x,is1,y,is2,&ctx);
55: VecScatterBegin(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
56: VecScatterEnd(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
58: PetscViewerASCIIPushSynchronized(PETSC_VIEWER_STDOUT_WORLD);
59: PetscViewerASCIISynchronizedPrintf(PETSC_VIEWER_STDOUT_WORLD,"----\n");
60: PetscViewerGetSubViewer(PETSC_VIEWER_STDOUT_WORLD,PETSC_COMM_SELF,&sviewer);
61: VecView(y,sviewer); fflush(stdout);
62: PetscViewerRestoreSubViewer(PETSC_VIEWER_STDOUT_WORLD,PETSC_COMM_SELF,&sviewer);
63: PetscViewerFlush(PETSC_VIEWER_STDOUT_WORLD);
64: PetscViewerASCIIPopSynchronized(PETSC_VIEWER_STDOUT_WORLD);
66: VecScatterDestroy(&ctx);
68: VecDestroy(&x);
69: VecDestroy(&y);
70: ISDestroy(&is1);
71: ISDestroy(&is2);
73: PetscFinalize();
74: return ierr;
75: }
79: /*TEST
81: testset:
82: nsize: 3
83: output_file: output/ex24_1.out
84: filter: grep -v " type:"
85: test:
86: suffix: standard
87: args: -vec_type standard
88: test:
89: requires: cuda
90: suffix: cuda
91: args: -vec_type cuda
92: test:
93: requires: viennacl
94: suffix: viennacl
95: args: -vec_type viennacl
97: TEST*/