1 2 static char help[] = "Tests MatCreateSubmatrix() in parallel."; 3 4 #include <petscmat.h> 5 6 int main(int argc, char **args) { 7 Mat C, A; 8 PetscInt i, j, m = 3, n = 2, rstart, rend; 9 PetscMPIInt size, rank; 10 PetscScalar v; 11 IS isrow, iscol; 12 13 PetscFunctionBeginUser; 14 PetscCall(PetscInitialize(&argc, &args, (char *)0, help)); 15 PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank)); 16 PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size)); 17 n = 2 * size; 18 19 PetscCall(MatCreate(PETSC_COMM_WORLD, &C)); 20 PetscCall(MatSetSizes(C, PETSC_DECIDE, PETSC_DECIDE, m * n, m * n)); 21 PetscCall(MatSetFromOptions(C)); 22 PetscCall(MatSetUp(C)); 23 24 /* 25 This is JUST to generate a nice test matrix, all processors fill up 26 the entire matrix. This is not something one would ever do in practice. 27 */ 28 PetscCall(MatGetOwnershipRange(C, &rstart, &rend)); 29 for (i = rstart; i < rend; i++) { 30 for (j = 0; j < m * n; j++) { 31 v = i + j + 1; 32 PetscCall(MatSetValues(C, 1, &i, 1, &j, &v, INSERT_VALUES)); 33 } 34 } 35 36 PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY)); 37 PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY)); 38 PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD, PETSC_VIEWER_ASCII_COMMON)); 39 PetscCall(MatView(C, PETSC_VIEWER_STDOUT_WORLD)); 40 41 /* 42 Generate a new matrix consisting of every second row and column of 43 the original matrix 44 */ 45 PetscCall(MatGetOwnershipRange(C, &rstart, &rend)); 46 /* Create parallel IS with the rows we want on THIS processor */ 47 PetscCall(ISCreateStride(PETSC_COMM_WORLD, (rend - rstart) / 2, rstart, 2, &isrow)); 48 /* Create parallel IS with the rows we want on THIS processor (same as rows for now) */ 49 PetscCall(ISCreateStride(PETSC_COMM_WORLD, (rend - rstart) / 2, rstart, 2, &iscol)); 50 51 PetscCall(MatCreateSubMatrix(C, isrow, iscol, MAT_INITIAL_MATRIX, &A)); 52 PetscCall(MatCreateSubMatrix(C, isrow, iscol, MAT_REUSE_MATRIX, &A)); 53 PetscCall(MatView(A, PETSC_VIEWER_STDOUT_WORLD)); 54 55 PetscCall(ISDestroy(&isrow)); 56 PetscCall(ISDestroy(&iscol)); 57 PetscCall(MatDestroy(&A)); 58 PetscCall(MatDestroy(&C)); 59 PetscCall(PetscFinalize()); 60 return 0; 61 } 62 63 /*TEST 64 65 test: 66 67 test: 68 suffix: 2 69 nsize: 3 70 71 test: 72 suffix: 2_baij 73 nsize: 3 74 args: -mat_type baij 75 76 test: 77 suffix: 2_sbaij 78 nsize: 3 79 args: -mat_type sbaij 80 81 test: 82 suffix: baij 83 args: -mat_type baij 84 output_file: output/ex59_1_baij.out 85 86 test: 87 suffix: sbaij 88 args: -mat_type sbaij 89 output_file: output/ex59_1_sbaij.out 90 91 TEST*/ 92