Initial commit for project 3..... A lot happend

src/project3/two_particles.cpp

@@ -0,0 +1,126 @@
+#include <armadillo>
+#include "classes.hpp"
+#include "solvers.hpp"
+#include "constants.hpp"
+#include "argparse/argparse.hpp"
+
+#include <iostream>
+
+using namespace std;
+
+int main(int argc, char* argv[]) {
+    argparse::ArgumentParser program("two_particles");
+    program.add_argument("-N", "--steps")
+        .help("Number of time steps")
+        .default_value(4000)
+        .scan<'i', int>();
+    program.add_argument("-n", "--num_particles")
+        .help("Number of particles (either 1 or 2)")
+        .default_value(2)
+        .scan<'i', int>();
+    program.add_argument("-i", "--disable-interactions")
+        .help("Disable Coulomb interactions")
+        .default_value(true)
+        .implicit_value(false);
+    program.add_argument("-E", "--euler")
+        .help("Use Euler solver instead of RK4")
+        .flag();
+    program.add_argument("-A", "--analytical")
+        .help("Use Analytical solver instead of RK4 (only valid for particles without interactions and specific initial conditions)")
+        .flag();
+    program.add_argument("-V", "--velocity-verlet")
+        .help("Use Velocity Verlet solver instead of RK4")
+        .flag();
+
+    try {
+        program.parse_args(argc, argv);
+    } catch (const runtime_error& err) {
+        cerr << err.what() << endl;
+        cerr << program.help().str() << endl;
+        exit(1);
+    }
+
+    double N = program.get<int>("--steps");
+    int n_particles = program.get<int>("--num_particles");
+    bool interactions = program.get<bool>("--disable-interactions");
+    bool use_euler = program.get<bool>("--euler");
+    bool use_analytical = program.get<bool>("--analytical");
+    bool use_velocity_verlet = program.get<bool>("--velocity-verlet");
+
+    double B_0 = 1.0; // Tesla
+    double V_0 = 0.025; // Volt
+    double d = 500e-6; // meter
+
+    PenningTrap trap(B_0, V_0, d);
+    if (interactions) {
+        trap.enable_interactions();
+    }
+    else {
+        trap.disable_interactions();
+    }
+    cout << trap << endl;
+
+
+    Particle p1(arma::vec({20e-6, 0, 20e-6}), arma::vec({0, 25, 0}), 40.078 * constants::amu, 1 * constants::elementary_charge);
+    Particle p2(arma::vec({25e-6, 25e-6, 0}), arma::vec({0, 40, 5}), 40.078 * constants::amu, 1 * constants::elementary_charge);
+
+    trap.add_particle(p1);
+    if (n_particles > 1) {
+        trap.add_particle(p2);
+    }
+
+    double dt = 50e-6 / N; // seconds
+
+    if (use_euler) {
+        EulerSolver solver(trap, dt);
+        solver.simulate(N);
+        solver.save("results/two_particles_" + std::to_string(n_particles) + (interactions ? "_with_interactions_" : "_no_interactions_") + std::to_string(N) + "_steps_euler");
+        vector<arma::mat> positions = solver.get_positions();
+        cout << "Final position of particle 1: " << endl;
+        cout << positions.back().col(0) << endl;
+        if (n_particles > 1) {
+            cout << "Final position of particle 2: " << endl;
+            cout << positions.back().col(1) << endl;
+        }
+        return 0;
+    }
+
+    if (use_analytical) {
+        AnalyticalSolver solver(trap, dt);
+        solver.simulate(N);
+        solver.save("results/two_particles_" + std::to_string(n_particles) + (interactions ? "_with_interactions_" : "_no_interactions_") + std::to_string(N) + "_steps_analytical");
+        vector<arma::mat> positions = solver.get_positions();
+        cout << "Final position of particle 1: " << endl;
+        cout << positions.back().col(0) << endl;
+        if (n_particles > 1) {
+            cout << "Final position of particle 2: " << endl;
+            cout << positions.back().col(1) << endl;
+        }
+        return 0;
+    }
+
+    if (use_velocity_verlet) {
+        VelocityVerletSolver solver(trap, dt);
+        solver.simulate(N);
+        solver.save("results/two_particles_" + std::to_string(n_particles) + (interactions ? "_with_interactions_" : "_no_interactions_") + std::to_string(N) + "_steps_velocity_verlet");
+        vector<arma::mat> positions = solver.get_positions();
+        cout << "Final position of particle 1: " << endl;
+        cout << positions.back().col(0) << endl;
+        if (n_particles > 1) {
+            cout << "Final position of particle 2: " << endl;
+            cout << positions.back().col(1) << endl;
+        }
+        return 0;
+    }
+
+    RK4Solver solver(trap, dt);
+    solver.simulate(N);
+    solver.save("results/two_particles_" + std::to_string(n_particles) + (interactions ? "_with_interactions_" : "_no_interactions_") + std::to_string(N) + "_steps_rk4");
+    vector<arma::mat> positions = solver.get_positions();
+    cout << "Final position of particle 1: " << endl;
+    cout << positions.back().col(0) << endl;
+    if (n_particles > 1) {
+        cout << "Final position of particle 2: " << endl;
+        cout << positions.back().col(1) << endl;
+    }
+}