added subdomain support in Mesh class, CalculateLaplaceMult implementation

mgrid_2/main.cpp

@@ -23,9 +23,10 @@ int main(int argc, char **argv )
     int nrefine = 0;
     if (argc > 1)  nrefine = atoi(argv[1]);
 
+
+    // generating the mesh
+    Mesh const mesh_c("../generate_mesh/coffee_cup.txt", "../generate_mesh/coffee_cup_sd.txt");
     //Mesh const mesh_c("square_tiny.txt");
-    Mesh const mesh_c("square_100.txt");
-    //Mesh const mesh_c("square.txt");
     bool ba = mesh_c.checkObtuseAngles();
     if (ba) cout << "mesh corrected" << endl;
 
@@ -34,33 +35,36 @@ int main(int argc, char **argv )
     //mesh.Debug();
     //mesh.DebugEdgeBased();
 
+
+    // Initializing FEM matrix !pattern! (only zero entries now)
     FEM_Matrix SK(mesh);                   // CRS matrix
     //SK.writeBinary("sparseMatrix.bin");
     //SK.Debug();
 
-    vector<double> uv(SK.Nrows(), 0.0);    // temperature
+
+    // Initialize RHS
     vector<double> fv(SK.Nrows(), 0.0);    // r.h.s.
 
-    SK.CalculateLaplace(fv);                       // matrix
-    SK.CalculateRHS(fv, [](double x, double y) {   // rhs
-        return std::sin(M_PI * 2.5 * y) * (M_PI * M_PI * 2.5 * 2.5 * x * x - 2);
-    }
-                   );
-    //SK.CheckRowSum();
-    SK.CheckMatrix();
+    // Calculate Matrix entries
+    SK.CalculateLaplaceMult(fv);                       // matrix
     //SK.Debug();
 
-    // Two ways to initialize the vector
-    //mesh.SetValues(uv,f_zero);             // user function
-    //mesh.SetValues(uv, [](double x, double y) -> double {return 0.0*x*y;} );  // lambda function
-    //mesh.SetValues(uv, [](double x, double y) -> double {return 5e-3*(x+1)*(y+1);} );  // lambda function
-    //
-    mesh.SetValues(uv, [](double x, double y) -> double {
-        return x *x * std::sin(2.5 * M_PI * y);
-    } );
+    // Calculate RHS
+     SK.CalculateRHS(fv, [](double x, double y) {   // rhs
+         return std::sin(M_PI * 2.5 * y) * (M_PI * M_PI * 2.5 * 2.5 * x * x - 2); });
+    //SK.CheckRowSum();
+    SK.CheckMatrix();
 
+    // Initialize temperature
+    vector<double> uv(SK.Nrows(), 0.0);    // temperature
+    mesh.SetValues(uv, [](double x, double y) -> double { return 18; } ); // initial temperature of every domain 
+
+
+    // Apply BC
     SK.ApplyDirichletBC(uv, fv);
 
+
+    // Solve
     auto exact_sol(uv);
     //SK.Mult(fv,uv);
 
@@ -73,6 +77,8 @@ int main(int argc, char **argv )
     double t_diff = static_cast<double>(duration.count()) / 1e6; // overall duration in seconds
     cout << "JacobiSolve: timing in sec. : " << t_diff << endl;
 
+
+    // Calculate error and visualize
     auto [val, idx] = findLargestAbsError(exact_sol, uv, 1e+6, 100);
 
     //mesh.Visualize(getAbsError(exact_sol, uv));