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Implement simulate method

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This commit is contained in:
Cory Balaton 2023-10-08 17:14:46 +02:00
parent a624173870
commit 5173a9e6f8
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GPG Key ID: 3E5FCEBFD80F432B
2 changed files with 86 additions and 38 deletions
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12
include/PenningTrap.hpp
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@ -18,8 +18,12 @@
#include "Particle.hpp" #include "Particle.hpp"
#include "constants.hpp" #include "constants.hpp"
#pragma omp declare reduction( + : arma::vec : omp_out += omp_in ) \ typedef std::vector<arma::vec::fixed<3>> sim_cols;
initializer( omp_priv = omp_orig ) typedef std::vector<arma::vec::fixed<3>> sim_rows;
typedef std::vector<sim_cols> sim_arr;
#pragma omp declare reduction(+ : arma::vec : omp_out += omp_in) \
initializer(omp_priv = omp_orig)
/** @brief A class that simulates a Penning trap. /** @brief A class that simulates a Penning trap.
* *
@ -36,7 +40,7 @@ private:
public: public:
/** @brief Set B_0, V_0 and d. /** @brief Set B_0, V_0 and d.
* */ * */
PenningTrap(double B_0 = T, double V_0 = 25.*V/1000., double d = 500.); PenningTrap(double B_0 = T, double V_0 = 25. * V / 1000., double d = 500.);
/** @brief Add a particle to the system /** @brief Add a particle to the system
* */ * */
@ -80,6 +84,8 @@ public:
* */ * */
void evolve_forward_euler(double dt); void evolve_forward_euler(double dt);
sim_arr simulate(double time, int steps, std::string method = "rk4");
arma::vec get_particle(int i); arma::vec get_particle(int i);
double get_d(); double get_d();

100
src/PenningTrap.cpp
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@ -16,6 +16,7 @@
#include "PenningTrap.hpp" #include "PenningTrap.hpp"
#include "constants.hpp" #include "constants.hpp"
#include "utils.hpp" #include "utils.hpp"
#include <cstdlib>
PenningTrap::PenningTrap(double B_0, double V_0, double d) PenningTrap::PenningTrap(double B_0, double V_0, double d)
{ {
@ -105,63 +106,71 @@ void PenningTrap::evolve_RK4(double dt)
{ {
std::vector<Particle> tmp_particles = this->particles; std::vector<Particle> tmp_particles = this->particles;
arma::vec::fixed<3> *k_v = new arma::vec::fixed<3>[this->particles.size()*4]; arma::vec::fixed<3> *k_v =
arma::vec::fixed<3> *k_r = new arma::vec::fixed<3>[this->particles.size()*4]; new arma::vec::fixed<3>[this->particles.size() * 4];
arma::vec::fixed<3> *k_r =
new arma::vec::fixed<3>[this->particles.size() * 4];
int size = this->particles.size(); int size = this->particles.size();
for (int i=0; i<size; i++) { for (int i = 0; i < size; i++) {
k_v[i] = this->total_force(i)/this->particles.at(i).m; k_v[i] = this->total_force(i) / this->particles.at(i).m;
k_r[i] = this->particles.at(i).v_vec; k_r[i] = this->particles.at(i).v_vec;
} }
for (int i=0; i<size; i++) { for (int i = 0; i < size; i++) {
Particle *p = &this->particles.at(i); Particle *p = &this->particles.at(i);
p->v_vec = tmp_particles.at(i).v_vec + (dt/2)*k_v[i]; p->v_vec = tmp_particles.at(i).v_vec + (dt / 2) * k_v[i];
p->r_vec = tmp_particles.at(i).r_vec + (dt/2)*k_r[i]; p->r_vec = tmp_particles.at(i).r_vec + (dt / 2) * k_r[i];
} }
for (int i = 0; i < size; i++) {
for (int i=0; i<size; i++) { k_v[1 * size + i] = this->total_force(i) / this->particles.at(i).m;
k_v[1*size + i] = this->total_force(i)/this->particles.at(i).m; k_r[1 * size + i] = this->particles.at(i).v_vec;
k_r[1*size + i] = this->particles.at(i).v_vec;
} }
for (int i=0; i<size; i++) { for (int i = 0; i < size; i++) {
Particle *p = &this->particles.at(i); Particle *p = &this->particles.at(i);
p->v_vec = tmp_particles.at(i).v_vec + (dt/2)*k_v[1*size + i]; p->v_vec = tmp_particles.at(i).v_vec + (dt / 2) * k_v[1 * size + i];
p->r_vec = tmp_particles.at(i).r_vec + (dt/2)*k_r[1*size + i]; p->r_vec = tmp_particles.at(i).r_vec + (dt / 2) * k_r[1 * size + i];
} }
for (int i=0; i<size; i++) { for (int i = 0; i < size; i++) {
k_v[2*size + i] = this->total_force(i)/this->particles.at(i).m; k_v[2 * size + i] = this->total_force(i) / this->particles.at(i).m;
k_r[2*size + i] = this->particles.at(i).v_vec; k_r[2 * size + i] = this->particles.at(i).v_vec;
} }
for (int i=0; i<size; i++) { for (int i = 0; i < size; i++) {
Particle *p = &this->particles.at(i); Particle *p = &this->particles.at(i);
p->v_vec = tmp_particles.at(i).v_vec + dt*k_v[2*size + i]; p->v_vec = tmp_particles.at(i).v_vec + dt * k_v[2 * size + i];
p->r_vec = tmp_particles.at(i).r_vec + dt*k_r[2*size + i]; p->r_vec = tmp_particles.at(i).r_vec + dt * k_r[2 * size + i];
} }
for (int i = 0; i < size; i++) {
for (int i=0; i<size; i++) { k_v[3 * size + i] = this->total_force(i) / this->particles.at(i).m;
k_v[3*size + i] = this->total_force(i)/this->particles.at(i).m; k_r[3 * size + i] = this->particles.at(i).v_vec;
k_r[3*size + i] = this->particles.at(i).v_vec;
} }
for (int i=0; i<size; i++) { for (int i = 0; i < size; i++) {
Particle *p = &this->particles.at(i); Particle *p = &this->particles.at(i);
p->v_vec = tmp_particles.at(i).v_vec + dt*(k_v[i] + k_v[size + i] + k_v[2*size + i] + k_v[3*size + i])/6; p->v_vec = tmp_particles.at(i).v_vec +
p->r_vec = tmp_particles.at(i).r_vec + dt*(k_r[i] + k_r[size + i] + k_r[2*size + i] + k_r[3*size + i])/6; dt *
(k_v[i] + k_v[size + i] + k_v[2 * size + i] +
k_v[3 * size + i]) /
6;
p->r_vec = tmp_particles.at(i).r_vec +
dt *
(k_r[i] + k_r[size + i] + k_r[2 * size + i] +
k_r[3 * size + i]) /
6;
} }
delete [] k_v; delete[] k_v;
delete [] k_r; delete[] k_r;
} }
void PenningTrap::evolve_forward_euler(double dt) void PenningTrap::evolve_forward_euler(double dt)
@ -180,6 +189,39 @@ void PenningTrap::evolve_forward_euler(double dt)
this->particles = new_state; this->particles = new_state;
} }
sim_arr PenningTrap::simulate(double time, int steps, std::string method)
{
double dt = time / (double)steps;
sim_arr res(this->particles.size(), sim_cols(steps));
std::function<void(double)> func;
if (method == "rk4") {
func = [this](double dt) {
this->evolve_RK4(dt);
};
}
else if(method == "euler") {
func = [this](double dt) {
this->evolve_forward_euler(dt);
};
}
else {
std::cout << "Not a valid method!" << std::endl;
abort();
}
int size = this->particles.size();
for (int j=0; j<steps; j++) {
for (int i=0;i<size;i++) {
res[i][j] = this->particles[i].r_vec;
}
func(dt);
}
return res;
}
arma::vec PenningTrap::get_particle(int i) arma::vec PenningTrap::get_particle(int i)
{ {
return this->particles.at(i).r_vec; return this->particles.at(i).r_vec;