1 2 static char help[] = "Tests relaxation for dense matrices.\n\n"; 3 4 #include <petscmat.h> 5 6 int main(int argc, char **args) 7 { 8 Mat C; 9 Vec u, x, b, e; 10 PetscInt i, n = 10, midx[3]; 11 PetscScalar v[3]; 12 PetscReal omega = 1.0, norm; 13 14 PetscFunctionBeginUser; 15 PetscCall(PetscInitialize(&argc, &args, (char *)0, help)); 16 PetscCall(PetscOptionsGetReal(NULL, NULL, "-omega", &omega, NULL)); 17 PetscCall(PetscOptionsGetInt(NULL, NULL, "-n", &n, NULL)); 18 19 PetscCall(MatCreate(PETSC_COMM_SELF, &C)); 20 PetscCall(MatSetSizes(C, n, n, n, n)); 21 PetscCall(MatSetType(C, MATSEQDENSE)); 22 PetscCall(MatSetUp(C)); 23 PetscCall(VecCreateSeq(PETSC_COMM_SELF, n, &b)); 24 PetscCall(VecCreateSeq(PETSC_COMM_SELF, n, &x)); 25 PetscCall(VecCreateSeq(PETSC_COMM_SELF, n, &u)); 26 PetscCall(VecCreateSeq(PETSC_COMM_SELF, n, &e)); 27 PetscCall(VecSet(u, 1.0)); 28 PetscCall(VecSet(x, 0.0)); 29 30 v[0] = -1.; 31 v[1] = 2.; 32 v[2] = -1.; 33 for (i = 1; i < n - 1; i++) { 34 midx[0] = i - 1; 35 midx[1] = i; 36 midx[2] = i + 1; 37 PetscCall(MatSetValues(C, 1, &i, 3, midx, v, INSERT_VALUES)); 38 } 39 i = 0; 40 midx[0] = 0; 41 midx[1] = 1; 42 v[0] = 2.0; 43 v[1] = -1.; 44 PetscCall(MatSetValues(C, 1, &i, 2, midx, v, INSERT_VALUES)); 45 i = n - 1; 46 midx[0] = n - 2; 47 midx[1] = n - 1; 48 v[0] = -1.0; 49 v[1] = 2.; 50 PetscCall(MatSetValues(C, 1, &i, 2, midx, v, INSERT_VALUES)); 51 52 PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY)); 53 PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY)); 54 55 PetscCall(MatMult(C, u, b)); 56 57 for (i = 0; i < n; i++) { 58 PetscCall(MatSOR(C, b, omega, SOR_FORWARD_SWEEP, 0.0, 1, 1, x)); 59 PetscCall(VecWAXPY(e, -1.0, x, u)); 60 PetscCall(VecNorm(e, NORM_2, &norm)); 61 PetscCall(PetscPrintf(PETSC_COMM_SELF, "2-norm of error %g\n", (double)norm)); 62 } 63 PetscCall(MatDestroy(&C)); 64 PetscCall(VecDestroy(&x)); 65 PetscCall(VecDestroy(&b)); 66 PetscCall(VecDestroy(&u)); 67 PetscCall(VecDestroy(&e)); 68 PetscCall(PetscFinalize()); 69 return 0; 70 } 71 72 /*TEST 73 74 test: 75 76 TEST*/ 77