1 static char help[] = "Tests automatic allocation of matrix storage space.\n\n"; 2 3 #include <petscmat.h> 4 5 int main(int argc, char **args) 6 { 7 Mat C; 8 PetscInt i, j, m = 3, n = 3, Ii, J; 9 PetscScalar v; 10 MatInfo info; 11 12 PetscFunctionBeginUser; 13 PetscCall(PetscInitialize(&argc, &args, NULL, help)); 14 PetscCall(PetscOptionsGetInt(NULL, NULL, "-m", &m, NULL)); 15 PetscCall(PetscOptionsGetInt(NULL, NULL, "-n", &n, NULL)); 16 17 /* create the matrix for the five point stencil, YET AGAIN */ 18 PetscCall(MatCreate(PETSC_COMM_SELF, &C)); 19 PetscCall(MatSetSizes(C, PETSC_DECIDE, PETSC_DECIDE, m * n, m * n)); 20 PetscCall(MatSetFromOptions(C)); 21 PetscCall(MatSetUp(C)); 22 for (i = 0; i < m; i++) { 23 for (j = 0; j < n; j++) { 24 v = -1.0; 25 Ii = j + n * i; 26 if (i > 0) { 27 J = Ii - n; 28 PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES)); 29 } 30 if (i < m - 1) { 31 J = Ii + n; 32 PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES)); 33 } 34 if (j > 0) { 35 J = Ii - 1; 36 PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES)); 37 } 38 if (j < n - 1) { 39 J = Ii + 1; 40 PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES)); 41 } 42 v = 4.0; 43 PetscCall(MatSetValues(C, 1, &Ii, 1, &Ii, &v, INSERT_VALUES)); 44 } 45 } 46 PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY)); 47 PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY)); 48 PetscCall(MatView(C, PETSC_VIEWER_STDOUT_SELF)); 49 50 PetscCall(MatGetInfo(C, MAT_LOCAL, &info)); 51 PetscCall(PetscPrintf(PETSC_COMM_SELF, "matrix nonzeros = %" PetscInt_FMT ", allocated nonzeros = %" PetscInt_FMT "\n", (PetscInt)info.nz_used, (PetscInt)info.nz_allocated)); 52 53 PetscCall(MatDestroy(&C)); 54 PetscCall(PetscFinalize()); 55 return 0; 56 } 57 58 /*TEST 59 60 test: 61 62 TEST*/ 63