copied the templates

mgrid_2/main.cpp

@@ -0,0 +1,141 @@
+#include "geom.h"
+#include "getmatrix.h"
+#include "jacsolve.h"
+#include "userset.h"
+#include "vdop.h"
+
+#include <cassert>
+#include <chrono>           // timing
+#include <cmath>
+#include <iostream>
+#include <omp.h>
+using namespace std;
+using namespace std::chrono;  // timing
+
+
+void Test_solver(int lev, vector<int> const &nthreads, Multigrid &ggm);
+
+int main(int argc, char **argv )
+{
+#undef MG
+#ifndef MG
+    // Jacobi iteration
+    int nrefine = 0;
+    if (argc > 1)  nrefine = atoi(argv[1]);
+
+    //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;
+
+    gMesh_Hierarchy ggm(mesh_c, nrefine);
+    const Mesh &mesh = ggm.finest();
+    //mesh.Debug();
+    //mesh.DebugEdgeBased();
+
+    FEM_Matrix SK(mesh);                   // CRS matrix
+    //SK.writeBinary("sparseMatrix.bin");
+    //SK.Debug();
+
+    vector<double> uv(SK.Nrows(), 0.0);    // temperature
+    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();
+    //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);
+    } );
+
+    SK.ApplyDirichletBC(uv, fv);
+
+    auto exact_sol(uv);
+    //SK.Mult(fv,uv);
+
+    auto t3 = system_clock::now(); // start timer
+
+    JacobiSolve(SK, fv, uv );          // solve the system of equations
+
+    auto t4 = system_clock::now();  // stop timer
+    auto duration = duration_cast<microseconds>(t4 - t3);        // duration in microseconds
+    double t_diff = static_cast<double>(duration.count()) / 1e6; // overall duration in seconds
+    cout << "JacobiSolve: timing in sec. : " << t_diff << endl;
+
+    auto [val, idx] = findLargestAbsError(exact_sol, uv, 1e+6, 100);
+
+    //mesh.Visualize(getAbsError(exact_sol, uv));
+    mesh.Visualize(uv);
+
+#else
+    // multigrid iteration
+    int nrefine = 3;
+    if (argc > 1)  nrefine = atoi(argv[1]);
+
+    //Multigrid ggm(Mesh("square_tiny.txt"),nrefine);
+    Multigrid ggm(Mesh("square_100.txt"), nrefine);
+
+    ggm.DefineOperators();
+
+    cout << "\n#############  SOLVE   ###############\n";
+
+    double tstart = omp_get_wtime();                  // OpenMP
+
+    //ggm.JacobiSolve(my_level);
+    //ggm.MG_Step(my_level, 1, true, 1);
+    ggm.MG_Solve(2, 1e-6, 1);
+
+    double t1 = omp_get_wtime() - tstart;             // OpenMP
+    cout << "MgSolve: timing in sec. : " << t1 << "   for " << ggm.Ndofs() << " dofs" << endl;
+
+
+    Test_solver(nrefine - 1, {1, 2, 4, 8, 16, 32, 64, 128, 256}, ggm);
+
+    //int my_level=nrefine-1;
+    //const auto &ml=ggm.GetMesh(my_level);
+    //const auto &sl=ggm.GetSolution(my_level);
+    //ml.Visualize(sl);
+    //////ml.Visualize_paraview(sl);
+    ////ml.Export_scicomp("level_"+to_string(my_level));
+
+    //int my_level=nrefine-1;
+    //const auto &mesh=ggm.GetMesh(my_level);
+    //const auto &uv=ggm.GetSolution(my_level);
+    //vector<double> exact_sol(size(uv));
+    //mesh.SetValues(exact_sol, [](double x, double y) -> double {
+    //return x * x * std::sin(2.5 * M_PI * y);
+    //} );
+    //mesh.Visualize(getAbsError(exact_sol, uv));
+
+#endif
+    return 0;
+}
+
+
+void Test_solver(int /*lev*/, vector<int> const &nthreads, Multigrid &ggm)
+{
+    cout << endl << endl << "-------------------------------------" << endl;
+    cout << "MgSolve: timing in sec. for " << ggm.Ndofs() << " dofs" << endl;
+    cout << "sec         threads" << endl;
+    vector<double> mg_time(size(nthreads), -1.0);
+
+    for (size_t k = 0; k < size(nthreads); ++k) {
+        omp_set_num_threads(nthreads.at(k));
+        double tstart = omp_get_wtime();
+        ggm.MG_Solve(2, 1e-6, 1);
+        double t1 = omp_get_wtime() - tstart;
+        mg_time.at(k) = t1;
+        cout << t1 << " : " << nthreads.at(k) << endl;
+    }
+}