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Length of element as L variable, not dx

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Уж больно это сильно мешало при чтении
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ParkSuMin
2025-09-21 22:46:12 +03:00
parent babcf0b877
commit 181e0874a6
2 changed files with 34 additions and 39 deletions
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70
Solver.cpp
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@@ -5,8 +5,7 @@ using namespace Eigen;
Solver::Solver(double _A, double _B, double _C, double _D, int _N, int _l, int _u) { Solver::Solver(double _A, double _B, double _C, double _D, int _N, int _l, int _u) {
A = _A, B = _B, C = _C, D = _D, N = _N; A = _A, B = _B, C = _C, D = _D, N = _N;
upper = _u, lower = _l; upper = _u, lower = _l;
L = upper - lower; L = (double)(upper - lower) / N;
dx = L / N;
} }
void Solver::Execute_Linear(double val1, double val2) { void Solver::Execute_Linear(double val1, double val2) {
@@ -14,13 +13,13 @@ void Solver::Execute_Linear(double val1, double val2) {
MatrixXd local = MatrixXd::Zero(2, 2); MatrixXd local = MatrixXd::Zero(2, 2);
VectorXd local_load(2); VectorXd local_load(2);
local(0, 0) = -A / dx - B / 2. + C * dx / 3.; local(0, 0) = -A / L - B / 2. + C * L / 3.;
local(0, 1) = A / dx + B / 2. + C * dx / 6.; local(0, 1) = A / L + B / 2. + C * L / 6.;
local(1, 0) = A / dx - B / 2. + C * dx / 6.; local(1, 0) = A / L - B / 2. + C * L / 6.;
local(1, 1) = -A / dx + B / 2. + C * dx / 3.; local(1, 1) = -A / L + B / 2. + C * L / 3.;
local_load(0) = -D * dx / 2.; local_load(0) = -D * L / 2.;
local_load(1) = -D * dx / 2.; local_load(1) = -D * L / 2.;
MatrixXd ansamb = MatrixXd::Zero(N + 1, N + 1); MatrixXd ansamb = MatrixXd::Zero(N + 1, N + 1);
VectorXd global_load = VectorXd::Zero(N + 1); VectorXd global_load = VectorXd::Zero(N + 1);
@@ -46,17 +45,13 @@ void Solver::Execute_Linear(double val1, double val2) {
#endif #endif
double u_right = val2; double u_right = val2;
// Clear first and last rows
ansamb.row(0).setZero(); ansamb.row(0).setZero();
ansamb.row(N).setZero(); ansamb.row(N).setZero();
// u'(0) = u(0) ansamb(0, 0) = L + 1;
ansamb(0, 0) = dx + 1;
ansamb(0, 1) = -1; ansamb(0, 1) = -1;
global_load(0) = 0; global_load(0) = 0;
// u(10) = u_right = 5
ansamb(N, N) = 1; ansamb(N, N) = 1;
global_load(N) = u_right; global_load(N) = u_right;
@@ -71,7 +66,7 @@ void Solver::Execute_Linear(double val1, double val2) {
std::cout << solution << std::endl; std::cout << solution << std::endl;
std::ofstream file("matrix_linear.txt"); std::ofstream file("matrix_linear.txt");
for (int i = 0; i < N; i++) { for (int i = 0; i < solution.size(); i++) {
file << solution(i) << ' '; file << solution(i) << ' ';
} }
file << std::endl; file << std::endl;
@@ -87,22 +82,22 @@ void Solver::Execute_Cubic(double val1, double val2) {
// Assemble matrix // Assemble matrix
for (int i = 0; i < mat_dim - 3; i += 3) { for (int i = 0; i < mat_dim - 3; i += 3) {
Amat(i, i + 0) -= A * 37.0 / 10.0 / dx; Amat(i, i + 0) -= A * 37.0 / 10.0 / L;
Amat(i, i + 1) -= A * (-189.0) / 40.0 / dx; Amat(i, i + 1) -= A * (-189.0) / 40.0 / L;
Amat(i, i + 2) -= A * 27.0 / 20.0 / dx; Amat(i, i + 2) -= A * 27.0 / 20.0 / L;
Amat(i, i + 3) -= A * (-13.0) / 40.0 / dx; Amat(i, i + 3) -= A * (-13.0) / 40.0 / L;
Amat(i + 1, i + 0) -= A * (-189.0) / 40.0 / dx; Amat(i + 1, i + 0) -= A * (-189.0) / 40.0 / L;
Amat(i + 1, i + 1) -= A * 54.0 / 5.0 / dx; Amat(i + 1, i + 1) -= A * 54.0 / 5.0 / L;
Amat(i + 1, i + 2) -= A * (-297.0) / 40.0 / dx; Amat(i + 1, i + 2) -= A * (-297.0) / 40.0 / L;
Amat(i + 1, i + 3) -= A * 27.0 / 20.0 / dx; Amat(i + 1, i + 3) -= A * 27.0 / 20.0 / L;
Amat(i + 2, i + 0) -= A * 27.0 / 20.0 / dx; Amat(i + 2, i + 0) -= A * 27.0 / 20.0 / L;
Amat(i + 2, i + 1) -= A * (-297.0) / 40.0 / dx; Amat(i + 2, i + 1) -= A * (-297.0) / 40.0 / L;
Amat(i + 2, i + 2) -= A * 54.0 / 5.0 / dx; Amat(i + 2, i + 2) -= A * 54.0 / 5.0 / L;
Amat(i + 2, i + 3) -= A * (-189.0) / 40.0 / dx; Amat(i + 2, i + 3) -= A * (-189.0) / 40.0 / L;
Amat(i + 3, i + 0) -= A * (-13.0) / 40.0 / dx; Amat(i + 3, i + 0) -= A * (-13.0) / 40.0 / L;
Amat(i + 3, i + 1) -= A * 27.0 / 20.0 / dx; Amat(i + 3, i + 1) -= A * 27.0 / 20.0 / L;
Amat(i + 3, i + 2) -= A * (-189.0) / 40.0 / dx; Amat(i + 3, i + 2) -= A * (-189.0) / 40.0 / L;
Amat(i + 3, i + 3) -= A * 37.0 / 10.0 / dx; Amat(i + 3, i + 3) -= A * 37.0 / 10.0 / L;
Amat(i + 0, i + 0) += B * (-1.0) / 2.0; Amat(i + 0, i + 0) += B * (-1.0) / 2.0;
Amat(i + 0, i + 1) += B * 57.0 / 80.0; Amat(i + 0, i + 1) += B * 57.0 / 80.0;
@@ -122,17 +117,16 @@ void Solver::Execute_Cubic(double val1, double val2) {
Amat(i + 3, i + 3) += B * 1.0 / 2.0; Amat(i + 3, i + 3) += B * 1.0 / 2.0;
} }
// Assembdxe vector // AssembLe vector
for (int i = 0; i < mat_dim - 3; i += 3) { for (int i = 0; i < mat_dim - 3; i += 3) {
b(i) -= D * dx / 8.0; b(i) -= D * L / 8.0;
b(i + 1) -= D * 3.0 * dx / 8.0; b(i + 1) -= D * 3.0 * L / 8.0;
b(i + 2) -= D * 3.0 * dx / 8.0; b(i + 2) -= D * 3.0 * L / 8.0;
b(i + 3) -= D * dx / 8.0; b(i + 3) -= D * L / 8.0;
} }
Amat.row(0).setZero(); Amat.row(0).setZero();
Amat(0, 0) = dx / 3.0 + 1; Amat(0, 0) = L / 3.0 + 1;
Amat(0, 1) = -1; Amat(0, 1) = -1;
b(0) = 0; b(0) = 0;
@@ -141,7 +135,7 @@ void Solver::Execute_Cubic(double val1, double val2) {
b(mat_dim - 1) = val2; b(mat_dim - 1) = val2;
// Решение системы // Решение системы
VectorXd solution = Amat.colPivHouseholderQr().solve(b); VectorXd solution = Amat.fullPivLu().solve(b);
std::cout << "\nSolution:" << std::endl; std::cout << "\nSolution:" << std::endl;
std::cout << solution << std::endl; std::cout << solution << std::endl;

3
Solver.h
View File

@@ -2,7 +2,8 @@
class Solver { class Solver {
private: private:
double A, B, C, D, L, dx; double A, B, C, D;
double L;
int N, upper, lower; int N, upper, lower;
public: public:
Solver(double _A, double _B, double _C, double _D, int _N, int _l, int _u); Solver(double _A, double _B, double _C, double _D, int _N, int _l, int _u);