From 4ab15cb13b252834b1b1ec756b5639fad7dd9c93 Mon Sep 17 00:00:00 2001
From: ParkSuMin <kamalovap@paksurion.ru>
Date: Sun, 21 Sep 2025 22:28:44 +0300
Subject: [PATCH] Ready linear element eval

---
 Solver.cpp | 55 +++++++++++++++++++++++++++---------------------------
 1 file changed, 28 insertions(+), 27 deletions(-)

diff --git a/Solver.cpp b/Solver.cpp
index 63845f1..d82257d 100644
--- a/Solver.cpp
+++ b/Solver.cpp
@@ -10,67 +10,68 @@ Solver::Solver(double _A, double _B, double _C, double _D, int _N, int _l, int _
 }
 
 void Solver::Execute_Linear(double val1, double val2) {
+
     MatrixXd local = MatrixXd::Zero(2, 2);
-    local(0, 0) = A / dx - B / 2.;
-    local(0, 1) = -A / dx + B / 2.;
-    local(1, 0) = -A / dx - B / 2.;
-    local(1, 1) = A / dx + B / 2.;
-    std::cout << "Local matrix:\n" << local << std::endl;
-
     VectorXd local_load(2);
-    local_load(0) = C * dx / 2;
-    local_load(1) = C * dx / 2;
 
-    // Ансаблированные матрицы и вектор
+    local(0, 0) = -A / dx - B / 2. + C * dx / 3.;
+    local(0, 1) = A / dx + B / 2. + C * dx / 6.;
+    local(1, 0) = A / dx - B / 2. + C * dx / 6.;
+    local(1, 1) = -A / dx + B / 2. + C * dx / 3.;
+
+    local_load(0) = -D * dx / 2.;
+    local_load(1) = -D * dx / 2.;
+
     MatrixXd ansamb = MatrixXd::Zero(N + 1, N + 1);
     VectorXd global_load = VectorXd::Zero(N + 1);
 
-    // Ансамблирование для каждого конечного элемента
+    // Ансамблирование
     for (int elem = 0; elem < N; ++elem) {
         int node_i = elem;
         int node_j = elem + 1;
 
-        // Матрица жесткости
         ansamb(node_i, node_i) += local(0, 0);
         ansamb(node_i, node_j) += local(0, 1);
         ansamb(node_j, node_i) += local(1, 0);
         ansamb(node_j, node_j) += local(1, 1);
 
-        // Вектор нагрузки
         global_load(node_i) += local_load(0);
         global_load(node_j) += local_load(1);
     }
 
+#if DEBUG
     std::cout << "Before:" << std::endl;
     std::cout << "Ansamb matrix:\n" << ansamb << std::endl;
     std::cout << "Ansamb load vector:\n" << global_load << std::endl;
+#endif
 
-    // ГУ 1-го рода
-    double u_left = val1;   // u(1) = 5
-    double u_right = val2; // u(6) = 15
+    double u_right = val2;
 
-    // Обнуляем первую строку и столбец матрицы, устанавливаем диагональ = 1
+    // Clear first and last rows
     ansamb.row(0).setZero();
-    ansamb.col(0).setZero();
-    ansamb(0, 0) = 1.0;
-    global_load(0) = u_left;
-
-    // Обнуляем последнюю строку и столбец матрицы, устанавливаем диагональ = 1
     ansamb.row(N).setZero();
-    ansamb.col(N).setZero();
-    ansamb(N, N) = 1.0;
+
+    // u'(0) = u(0)
+    ansamb(0, 0) = dx + 1;
+    ansamb(0, 1) = -1;
+    global_load(0) = 0;
+
+    // u(10) = u_right = 5
+    ansamb(N, N) = 1;
     global_load(N) = u_right;
 
+#if DEBUG
     std::cout << "\nAfter:" << std::endl;
     std::cout << "Modified matrix:\n" << ansamb << std::endl;
     std::cout << "Modified load vector:\n" << global_load << std::endl;
+#endif
 
     VectorXd solution = ansamb.fullPivLu().solve(global_load);
     std::cout << "\nSolution:" << std::endl;
     std::cout << solution << std::endl;
 
-    std::ofstream file("matrix_2.txt");
-    for (int i = 0; i < N + 1; i++) {
+    std::ofstream file("matrix_linear.txt");
+    for (int i = 0; i < N; i++) {
         file << solution(i) << ' ';
     }
     file << std::endl;
@@ -119,7 +120,7 @@ void Solver::Execute_Cubic(double val1, double val2) {
         Amat(i + 3, i + 1) += B * 3.0 / 10.0;
         Amat(i + 3, i + 2) += B * (-57.0) / 80.0;
         Amat(i + 3, i + 3) += B * 1.0 / 2.0;
-        }
+    }
 
     // Assembdxe vector
     for (int i = 0; i < mat_dim - 3; i += 3) {
@@ -143,7 +144,7 @@ void Solver::Execute_Cubic(double val1, double val2) {
     VectorXd solution = Amat.colPivHouseholderQr().solve(b);
     std::cout << "\nSolution:" << std::endl;
     std::cout << solution << std::endl;
-
+    
     std::ofstream file("matrix_cubic.txt");
     for (int i = 0; i < solution.size(); i++) {
         file << solution(i) << ' ';