copied the templates

mgrid_2/main.cpp.orig

@@ -0,0 +1,165 @@
+//		MPI code in C++.
+//		See [Gropp/Lusk/Skjellum, "Using MPI", p.33/41 etc.]
+//		and  /opt/mpich/include/mpi2c++/comm.h  for details
+
+#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("square_tiny.txt");
+        //Mesh const mesh("square_100.txt");
+        //Mesh const mesh("L_shape.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;
+        //mesh_c.Debug();
+        //mesh_c.DebugEdgeBased();
+
+        //RefinedMesh mesh(mesh_c);                  // OK, works
+        //Mesh const mesh("square_tiny.txt");
+        ////mesh.Debug();
+        //mesh.RefineAllElements(nrefine);           // OK, works
+
+        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();
+        //return 0;
+        //SK.Debug();
+
+        //mesh.SetU(uv);         // deprecated
+        // 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);
+
+        //SK.Compare2Old(nnode, id, ik, sk);
+        //SK.Debug();
+        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.Write_ascii_matlab("uv.txt", 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;
+    }
+}