1 2 static char help[] = "Tests MatCreateSubMatrices().\n\n"; 3 4 #include <petscmat.h> 5 6 int main(int argc, char **args) 7 { 8 Mat A, B, *Bsub; 9 PetscInt i, j, m = 6, n = 6, N = 36, Ii, J; 10 PetscScalar v; 11 IS isrow; 12 13 PetscFunctionBeginUser; 14 PetscCall(PetscInitialize(&argc, &args, (char *)0, help)); 15 PetscCall(MatCreateSeqAIJ(PETSC_COMM_WORLD, N, N, 5, NULL, &A)); 16 for (i = 0; i < m; i++) { 17 for (j = 0; j < n; j++) { 18 v = -1.0; 19 Ii = j + n * i; 20 if (i > 0) { 21 J = Ii - n; 22 PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES)); 23 } 24 if (i < m - 1) { 25 J = Ii + n; 26 PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES)); 27 } 28 if (j > 0) { 29 J = Ii - 1; 30 PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES)); 31 } 32 if (j < n - 1) { 33 J = Ii + 1; 34 PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES)); 35 } 36 v = 4.0; 37 PetscCall(MatSetValues(A, 1, &Ii, 1, &Ii, &v, INSERT_VALUES)); 38 } 39 } 40 PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY)); 41 PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY)); 42 PetscCall(MatView(A, PETSC_VIEWER_STDOUT_SELF)); 43 44 /* take the first diagonal block */ 45 PetscCall(ISCreateStride(PETSC_COMM_WORLD, m, 0, 1, &isrow)); 46 PetscCall(MatCreateSubMatrices(A, 1, &isrow, &isrow, MAT_INITIAL_MATRIX, &Bsub)); 47 B = *Bsub; 48 PetscCall(ISDestroy(&isrow)); 49 PetscCall(MatView(B, PETSC_VIEWER_STDOUT_SELF)); 50 PetscCall(MatDestroySubMatrices(1, &Bsub)); 51 52 /* take a strided block */ 53 PetscCall(ISCreateStride(PETSC_COMM_WORLD, m, 0, 2, &isrow)); 54 PetscCall(MatCreateSubMatrices(A, 1, &isrow, &isrow, MAT_INITIAL_MATRIX, &Bsub)); 55 B = *Bsub; 56 PetscCall(ISDestroy(&isrow)); 57 PetscCall(MatView(B, PETSC_VIEWER_STDOUT_SELF)); 58 PetscCall(MatDestroySubMatrices(1, &Bsub)); 59 60 /* take the last block */ 61 PetscCall(ISCreateStride(PETSC_COMM_WORLD, m, N - m - 1, 1, &isrow)); 62 PetscCall(MatCreateSubMatrices(A, 1, &isrow, &isrow, MAT_INITIAL_MATRIX, &Bsub)); 63 B = *Bsub; 64 PetscCall(ISDestroy(&isrow)); 65 PetscCall(MatView(B, PETSC_VIEWER_STDOUT_SELF)); 66 67 PetscCall(MatDestroySubMatrices(1, &Bsub)); 68 PetscCall(MatDestroy(&A)); 69 70 PetscCall(PetscFinalize()); 71 return 0; 72 } 73 74 /*TEST 75 76 test: 77 78 TEST*/ 79