1 static char help[]= " Test VecScatter with x, y on different communicators\n\n"; 2 3 #include <petscvec.h> 4 5 int main(int argc,char **argv) 6 { 7 PetscErrorCode ierr; 8 PetscInt i,n=5,rstart; 9 PetscScalar *val; 10 const PetscScalar *dat; 11 Vec x,y1,y2; 12 MPI_Comm newcomm; 13 PetscMPIInt nproc,rank; 14 IS ix; 15 VecScatter vscat1,vscat2; 16 17 PetscFunctionBegin; 18 ierr = PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr; 19 CHKERRMPI(MPI_Comm_size(PETSC_COMM_WORLD,&nproc)); 20 CHKERRMPI(MPI_Comm_rank(PETSC_COMM_WORLD,&rank)); 21 22 PetscCheckFalse(nproc != 2,PETSC_COMM_WORLD,PETSC_ERR_WRONG_MPI_SIZE,"This test must run with exactly two MPI ranks"); 23 24 /* Create MPI vectors x and y, which are on the same comm (i.e., MPI_IDENT) */ 25 CHKERRQ(VecCreateMPI(PETSC_COMM_WORLD,n,PETSC_DECIDE,&x)); 26 CHKERRQ(VecDuplicate(x,&y1)); 27 CHKERRQ(VecGetOwnershipRange(x,&rstart,NULL)); 28 29 /* Set x's value locally. x would be {0., 1., 2., ..., 9.} */ 30 CHKERRQ(VecGetArray(x,&val)); 31 for (i=0; i<n; i++) val[i] = rstart + i; 32 CHKERRQ(VecRestoreArray(x,&val)); 33 34 /* Create index set ix = {0, 1, 2, ..., 9} */ 35 CHKERRQ(ISCreateStride(PETSC_COMM_WORLD,n,rstart,1,&ix)); 36 37 /* Create newcomm that reverses processes in x's comm, and then create y2 on it*/ 38 CHKERRMPI(MPI_Comm_split(PETSC_COMM_WORLD,0/*color*/,-rank/*key*/,&newcomm)); 39 CHKERRQ(VecCreateMPI(newcomm,n,PETSC_DECIDE,&y2)); 40 41 /* It looks vscat1/2 are the same, but actually not. y2 is on a different communicator than x */ 42 CHKERRQ(VecScatterCreate(x,ix,y1,ix,&vscat1)); 43 CHKERRQ(VecScatterCreate(x,ix,y2,ix,&vscat2)); 44 45 CHKERRQ(VecScatterBegin(vscat1,x,y1,INSERT_VALUES,SCATTER_FORWARD)); 46 CHKERRQ(VecScatterBegin(vscat2,x,y2,INSERT_VALUES,SCATTER_FORWARD)); 47 CHKERRQ(VecScatterEnd (vscat1,x,y1,INSERT_VALUES,SCATTER_FORWARD)); 48 CHKERRQ(VecScatterEnd (vscat2,x,y2,INSERT_VALUES,SCATTER_FORWARD)); 49 50 /* View on rank 0 of x's comm, which is PETSC_COMM_WORLD */ 51 if (rank == 0) { 52 /* Print the part of x on rank 0, which is 0 1 2 3 4 */ 53 CHKERRQ(PetscPrintf(PETSC_COMM_SELF,"\nOn rank 0 of PETSC_COMM_WORLD, x = ")); 54 CHKERRQ(VecGetArrayRead(x,&dat)); 55 for (i=0; i<n; i++) CHKERRQ(PetscPrintf(PETSC_COMM_SELF," %.0g",(double)PetscRealPart(dat[i]))); 56 CHKERRQ(VecRestoreArrayRead(x,&dat)); 57 58 /* Print the part of y1 on rank 0, which is 0 1 2 3 4 */ 59 CHKERRQ(PetscPrintf(PETSC_COMM_SELF,"\nOn rank 0 of PETSC_COMM_WORLD, y1 = ")); 60 CHKERRQ(VecGetArrayRead(y1,&dat)); 61 for (i=0; i<n; i++) CHKERRQ(PetscPrintf(PETSC_COMM_SELF," %.0g",(double)PetscRealPart(dat[i]))); 62 CHKERRQ(VecRestoreArrayRead(y1,&dat)); 63 64 /* Print the part of y2 on rank 0, which is 5 6 7 8 9 since y2 swapped the processes of PETSC_COMM_WORLD */ 65 CHKERRQ(PetscPrintf(PETSC_COMM_SELF,"\nOn rank 0 of PETSC_COMM_WORLD, y2 = ")); 66 CHKERRQ(VecGetArrayRead(y2,&dat)); 67 for (i=0; i<n; i++) CHKERRQ(PetscPrintf(PETSC_COMM_SELF," %.0g",(double)PetscRealPart(dat[i]))); 68 CHKERRQ(VecRestoreArrayRead(y2,&dat)); 69 CHKERRQ(PetscPrintf(PETSC_COMM_SELF,"\n")); 70 } 71 72 CHKERRQ(ISDestroy(&ix)); 73 CHKERRQ(VecDestroy(&x)); 74 CHKERRQ(VecDestroy(&y1)); 75 CHKERRQ(VecDestroy(&y2)); 76 CHKERRQ(VecScatterDestroy(&vscat1)); 77 CHKERRQ(VecScatterDestroy(&vscat2)); 78 CHKERRMPI(MPI_Comm_free(&newcomm)); 79 ierr = PetscFinalize(); 80 return ierr; 81 } 82 83 /*TEST 84 85 test: 86 nsize: 2 87 requires: double 88 TEST*/ 89