Second example, additional commentary

examples/CMakeLists.txt

@@ -1,3 +1,5 @@
 add_executable(first_example first_example.cpp)
+add_executable(second_example second_example.cpp)
 
-target_link_libraries(first_example tug)
+target_link_libraries(first_example tug)
+target_link_libraries(second_example tug)

examples/second_example.cpp

@@ -0,0 +1,57 @@
+#include "tug/BoundaryCondition.hpp"
+#include <tug/Diffusion.hpp>
+
+#include <iostream>
+
+using namespace std;
+using namespace tug::diffusion;
+using namespace tug::bc;
+
+int main(int argc, char *argv[]) {
+
+    int dim = 2;
+    int n = 5;
+    int m = 5;
+
+    vector<double> alpha(n * m, 1e-1);
+    vector<double> field(n * m, 0);
+    field[0] = 1e-6;
+    // for (int i = 1; i<20; i++) {
+    //     for (int j = 0; j<20; j++ ) {
+    //         field[i] = 0;
+    //     }
+    // }
+
+    // print field
+    cout << "Initial field:" << endl;
+    for (int i = 0; i<n; i++) {
+        for (int j = 0; j<m; j++) {
+            cout << field[n * i + j] << " ";
+        }
+        cout << endl;
+    }
+    cout << endl;
+
+    TugInput input_param;
+    input_param.setTimestep(1.);
+    input_param.setGridCellN(n, m);
+    input_param.setDomainSize(n, m);
+    BoundaryCondition bc(n, m);
+    input_param.setBoundaryCondition(bc);
+
+    int iterations = 1000;
+    for (int t = 0; t < iterations; t++) {
+        double result = ADI_2D(input_param, &field[0], &alpha[0]);
+
+        if (t % 100 == 0) {
+            cout << "Iteration " << t << ":" << endl;
+            for (int i = 0; i<n; i++) {
+                for (int j = 0; j<m; j++) {
+                    cout << field[n * i + j] << " ";
+                }
+                cout << endl;
+            }
+            cout << endl;
+        }
+    }
+}

include/tug/Solver.hpp

@@ -23,7 +23,7 @@ auto EigenLU(const Eigen::SparseMatrix<double> &A_matrix,
 
 /**
  * Solving linear equation system with brutal implementation of the Thomas
- * algorithm.
+ * algorithm (a.k.a. Tridiagonal matrix algorithm).
  *
  * \param A_matrix The A matrix represented as a sparse matrix using Eigen
  * library.