1 2 static char help[] = "Partition tiny grid.\n\n"; 3 4 /*T 5 Concepts: partitioning 6 Processors: 4 7 T*/ 8 9 /* 10 Include "petscmat.h" so that we can use matrices. Note that this file 11 automatically includes: 12 petscsys.h - base PETSc routines petscvec.h - vectors 13 petscmat.h - matrices 14 petscis.h - index sets 15 petscviewer.h - viewers 16 */ 17 #include <petscmat.h> 18 19 int main(int argc,char **args) 20 { 21 Mat A; 22 PetscMPIInt rank,size; 23 PetscInt *ia,*ja; 24 MatPartitioning part; 25 IS is,isn; 26 27 PetscCall(PetscInitialize(&argc,&args,(char*)0,help)); 28 PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD,&size)); 29 PetscCheckFalse(size != 4,PETSC_COMM_WORLD,PETSC_ERR_WRONG_MPI_SIZE,"Must run with 4 processors"); 30 PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD,&rank)); 31 32 PetscCall(PetscMalloc1(5,&ia)); 33 PetscCall(PetscMalloc1(16,&ja)); 34 if (rank == 0) { 35 ja[0] = 1; ja[1] = 4; ja[2] = 0; ja[3] = 2; ja[4] = 5; ja[5] = 1; ja[6] = 3; ja[7] = 6; 36 ja[8] = 2; ja[9] = 7; 37 ia[0] = 0; ia[1] = 2; ia[2] = 5; ia[3] = 8; ia[4] = 10; 38 } else if (rank == 1) { 39 ja[0] = 0; ja[1] = 5; ja[2] = 8; ja[3] = 1; ja[4] = 4; ja[5] = 6; ja[6] = 9; ja[7] = 2; 40 ja[8] = 5; ja[9] = 7; ja[10] = 10; ja[11] = 3; ja[12] = 6; ja[13] = 11; 41 ia[0] = 0; ia[1] = 3; ia[2] = 7; ia[3] = 11; ia[4] = 14; 42 } else if (rank == 2) { 43 ja[0] = 4; ja[1] = 9; ja[2] = 12; ja[3] = 5; ja[4] = 8; ja[5] = 10; ja[6] = 13; ja[7] = 6; 44 ja[8] = 9; ja[9] = 11; ja[10] = 14; ja[11] = 7; ja[12] = 10; ja[13] = 15; 45 ia[0] = 0; ia[1] = 3; ia[2] = 7; ia[3] = 11; ia[4] = 14; 46 } else { 47 ja[0] = 8; ja[1] = 13; ja[2] = 9; ja[3] = 12; ja[4] = 14; ja[5] = 10; ja[6] = 13; ja[7] = 15; 48 ja[8] = 11; ja[9] = 14; 49 ia[0] = 0; ia[1] = 2; ia[2] = 5; ia[3] = 8; ia[4] = 10; 50 } 51 52 PetscCall(MatCreateMPIAdj(PETSC_COMM_WORLD,4,16,ia,ja,NULL,&A)); 53 PetscCall(MatView(A,PETSC_VIEWER_STDOUT_WORLD)); 54 55 /* 56 Partition the graph of the matrix 57 */ 58 PetscCall(MatPartitioningCreate(PETSC_COMM_WORLD,&part)); 59 PetscCall(MatPartitioningSetAdjacency(part,A)); 60 PetscCall(MatPartitioningSetFromOptions(part)); 61 /* get new processor owner number of each vertex */ 62 PetscCall(MatPartitioningApply(part,&is)); 63 /* get new global number of each old global number */ 64 PetscCall(ISPartitioningToNumbering(is,&isn)); 65 PetscCall(ISView(isn,PETSC_VIEWER_STDOUT_WORLD)); 66 PetscCall(ISDestroy(&is)); 67 68 PetscCall(ISDestroy(&isn)); 69 PetscCall(MatPartitioningDestroy(&part)); 70 71 /* 72 Free work space. All PETSc objects should be destroyed when they 73 are no longer needed. 74 */ 75 PetscCall(MatDestroy(&A)); 76 77 PetscCall(PetscFinalize()); 78 return 0; 79 } 80