1 static char help[]= "Test vecscatter of different block sizes across processes\n\n"; 2 3 #include <petscvec.h> 4 int main(int argc,char **argv) 5 { 6 PetscInt i,bs,n,low,high; 7 PetscMPIInt nproc,rank; 8 Vec x,y,z; 9 IS ix,iy; 10 VecScatter vscat; 11 const PetscScalar *yv; 12 13 PetscCall(PetscInitialize(&argc,&argv,(char*)0,help)); 14 PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD,&nproc)); 15 PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD,&rank)); 16 PetscCheck(nproc == 2,PETSC_COMM_WORLD,PETSC_ERR_WRONG_MPI_SIZE,"This test can only run on two MPI ranks"); 17 18 /* Create an MPI vector x of size 12 on two processes, and set x = {0, 1, 2, .., 11} */ 19 PetscCall(VecCreateMPI(PETSC_COMM_WORLD,6,PETSC_DECIDE,&x)); 20 PetscCall(VecGetOwnershipRange(x,&low,&high)); 21 for (i=low; i<high; i++) PetscCall(VecSetValue(x,i,(PetscScalar)i,INSERT_VALUES)); 22 PetscCall(VecAssemblyBegin(x)); 23 PetscCall(VecAssemblyEnd(x)); 24 25 /* Create a seq vector y, and a parallel to sequential (PtoS) vecscatter to scatter x to y */ 26 if (rank == 0) { 27 /* On rank 0, seq y is of size 6. We will scatter x[0,1,2,6,7,8] to y[0,1,2,3,4,5] using IS with bs=3 */ 28 PetscInt idx[2]={0,2}; 29 PetscInt idy[2]={0,1}; 30 n = 6; 31 bs = 3; 32 PetscCall(VecCreateSeq(PETSC_COMM_SELF,n,&y)); 33 PetscCall(ISCreateBlock(PETSC_COMM_SELF,bs,2,idx,PETSC_COPY_VALUES,&ix)); 34 PetscCall(ISCreateBlock(PETSC_COMM_SELF,bs,2,idy,PETSC_COPY_VALUES,&iy)); 35 } else { 36 /* On rank 1, seq y is of size 4. We will scatter x[4,5,10,11] to y[0,1,2,3] using IS with bs=2 */ 37 PetscInt idx[2]= {2,5}; 38 PetscInt idy[2]= {0,1}; 39 n = 4; 40 bs = 2; 41 PetscCall(VecCreateSeq(PETSC_COMM_SELF,n,&y)); 42 PetscCall(ISCreateBlock(PETSC_COMM_SELF,bs,2,idx,PETSC_COPY_VALUES,&ix)); 43 PetscCall(ISCreateBlock(PETSC_COMM_SELF,bs,2,idy,PETSC_COPY_VALUES,&iy)); 44 } 45 PetscCall(VecScatterCreate(x,ix,y,iy,&vscat)); 46 47 /* Do the vecscatter */ 48 PetscCall(VecScatterBegin(vscat,x,y,INSERT_VALUES,SCATTER_FORWARD)); 49 PetscCall(VecScatterEnd(vscat,x,y,INSERT_VALUES,SCATTER_FORWARD)); 50 51 /* Print y. Since y is sequential, we put y in a parallel z to print its value on both ranks */ 52 PetscCall(VecGetArrayRead(y,&yv)); 53 PetscCall(VecCreateMPIWithArray(PETSC_COMM_WORLD,1,n,PETSC_DECIDE,yv,&z)); 54 PetscCall(VecView(z,PETSC_VIEWER_STDOUT_WORLD)); 55 PetscCall(VecRestoreArrayRead(y,&yv)); 56 57 PetscCall(ISDestroy(&ix)); 58 PetscCall(ISDestroy(&iy)); 59 PetscCall(VecDestroy(&x)); 60 PetscCall(VecDestroy(&y)); 61 PetscCall(VecDestroy(&z)); 62 PetscCall(VecScatterDestroy(&vscat)); 63 64 PetscCall(PetscFinalize()); 65 return 0; 66 } 67 68 /*TEST 69 70 test: 71 nsize: 2 72 args: 73 requires: 74 TEST*/ 75