Coryab/implement rk4 #5

Merged
coryab merged 5 commits from coryab/implement-RK4 into develop 2023-10-07 22:37:35 +00:00
3 changed files with 66 additions and 72 deletions
Showing only changes of commit e17da401ec - Show all commits

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@ -21,52 +21,54 @@
#define CHARGE 1. #define CHARGE 1.
#define MASS 40. // unit: amu #define MASS 40. // unit: amu
void euler_100_particles() void simulate_100_particles()
{ {
PenningTrap trap; PenningTrap trap;
// Add particles inside trap // Add particles inside trap
for (int i=0; i < PARTICLES; i++) { for (int i = 0; i < PARTICLES; i++) {
arma::vec r = arma::vec(3).randn() * 0.1 * trap.get_d(); // random initial position arma::vec r = arma::vec(3).randn() * 0.1 *
arma::vec v = arma::vec(3).randn() * 0.1 * trap.get_d(); // random initial velocity trap.get_d(); // random initial position
arma::vec v = arma::vec(3).randn() * 0.1 *
trap.get_d(); // random initial velocity
trap.add_particle(Particle(CHARGE, MASS, r, v)); trap.add_particle(Particle(CHARGE, MASS, r, v));
} }
double time = 50.; // microseconds double time = 50.; // microseconds
double dt = time / (double) N; double dt = time / (double)N;
auto res = new arma::vec::fixed<3>[PARTICLES][N]; auto res = new arma::vec::fixed<3>[PARTICLES][N];
int counter = 0; int counter = 0;
// Get the path of all particles // Get the path of all particles
for (int j=0; j < N; j++) { for (int j = 0; j < N; j++) {
#pragma omp parallel for #pragma omp parallel for
for (int i=0; i < PARTICLES; i++) { for (int i = 0; i < PARTICLES; i++) {
res[i][j] = trap.get_particle(i); res[i][j] = trap.get_particle(i);
} }
trap.evolve_forward_euler(dt); trap.evolve_RK4(dt);
} }
std::cout << counter << std::endl; std::cout << counter << std::endl;
arma::vec::fixed<3>* cur_row; arma::vec::fixed<3> *cur_row;
arma::vec::fixed<3> cur_elem; arma::vec::fixed<3> cur_elem;
mkdir("output", 0777); mkdir("output", 0777);
mkdir("output/simulate_100_particles", 0777);
std::ofstream ofile; std::ofstream ofile;
// Write particle paths to file // Write particle paths to file
#pragma omp parallel for private(cur_row, cur_elem, ofile) #pragma omp parallel for private(cur_row, cur_elem, ofile)
for (int i=0; i < PARTICLES; i++) { for (int i = 0; i < PARTICLES; i++) {
cur_row = res[i]; cur_row = res[i];
ofile.open("output/p" + std::to_string(i) + ".txt"); ofile.open("output/simulate_100_particles/p" + std::to_string(i) + ".txt");
for (int j=0; j < N; j++) { for (int j = 0; j < N; j++) {
cur_elem = cur_row[j]; cur_elem = cur_row[j];
ofile << cur_elem(0) << "," ofile << cur_elem(0) << "," << cur_elem(1) << "," << cur_elem(2)
<< cur_elem(1) << "," << "\n";
<< cur_elem(2) << "\n";
} }
ofile.close(); ofile.close();
} }
@ -76,7 +78,7 @@ int main()
{ {
double start = omp_get_wtime(); double start = omp_get_wtime();
euler_100_particles(); simulate_100_particles();
double end = omp_get_wtime(); double end = omp_get_wtime();

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@ -26,26 +26,25 @@ public:
// Vector containing inputs and expected results // Vector containing inputs and expected results
std::vector<std::pair<arma::vec, arma::vec>> tests; std::vector<std::pair<arma::vec, arma::vec>> tests;
tests.push_back(std::make_pair(arma::vec{0.,0.,0.}, tests.push_back(
arma::vec{0.,0.,0.})); std::make_pair(arma::vec{0., 0., 0.}, arma::vec{0., 0., 0.}));
tests.push_back(std::make_pair(arma::vec{10.,0.,0.}, tests.push_back(std::make_pair(arma::vec{10., 0., 0.},
arma::vec{96.4852558,0.,0.})); arma::vec{96.4852558, 0., 0.}));
tests.push_back(std::make_pair(arma::vec{10.,0.,0.}, tests.push_back(std::make_pair(arma::vec{10., 0., 0.},
arma::vec{96.4852558,0.,0.})); arma::vec{96.4852558, 0., 0.}));
tests.push_back(std::make_pair(arma::vec{0.,10.,0.}, tests.push_back(std::make_pair(arma::vec{0., 10., 0.},
arma::vec{0.,96.4852558,0.})); arma::vec{0., 96.4852558, 0.}));
tests.push_back(std::make_pair(arma::vec{0.,0.,10.},
arma::vec{0.,0.,-192.9705116}));
tests.push_back(std::make_pair(arma::vec{0., 0., 10.},
arma::vec{0., 0., -192.9705116}));
arma::vec result; arma::vec result;
arma::vec v; arma::vec v;
std::stringstream msg; std::stringstream msg;
for (int i=0; i < tests.size(); i++) { for (int i = 0; i < tests.size(); i++) {
v = tests.at(i).first; v = tests.at(i).first;
result = trap.external_E_field(v); result = trap.external_E_field(v);
@ -57,31 +56,29 @@ public:
} }
} }
static void test_external_B_field() static void test_external_B_field()
{ {
// No point in testing at different points since it's not dependent on // No point in testing at different points since it's not dependent
// position. // on position.
PenningTrap trap; PenningTrap trap;
arma::vec expected{0.,0.,T}; arma::vec expected{0., 0., T};
arma::vec result = trap.external_B_field(arma::vec{0.,0.,0.}); arma::vec result = trap.external_B_field(arma::vec{0., 0., 0.});
ASSERT(arma_vector_close_to(expected, result), ASSERT(arma_vector_close_to(expected, result),
"Testing the external B field at (0,0,0)"); "Testing the external B field at (0,0,0)");
} }
static void test_force_on_particle() static void test_force_on_particle()
{ {
PenningTrap trap; PenningTrap trap;
arma::vec v{0.,0.,0.}; arma::vec v{0., 0., 0.};
// Add particles to test // Add particles to test
trap.add_particle(Particle(1.,40.,arma::vec{0.,0.,0.},v)); trap.add_particle(Particle(1., 40., arma::vec{0., 0., 0.}, v));
trap.add_particle(Particle(1.,40.,arma::vec{1.,0.,0.},v)); trap.add_particle(Particle(1., 40., arma::vec{1., 0., 0.}, v));
trap.add_particle(Particle(1.,40.,arma::vec{0.,3.,4.},v)); trap.add_particle(Particle(1., 40., arma::vec{0., 3., 4.}, v));
// Test p0 and p1 // Test p0 and p1
arma::vec expected{-1.,0.,0.}; arma::vec expected{-1., 0., 0.};
arma::vec result = trap.force_on_particle(0, 1); arma::vec result = trap.force_on_particle(0, 1);
ASSERT(arma_vector_close_to(expected, result), ASSERT(arma_vector_close_to(expected, result),
"Testing the force on a particle at (0,0,0) from a " "Testing the force on a particle at (0,0,0) from a "
@ -98,10 +95,10 @@ public:
static void test_total_force_external() static void test_total_force_external()
{ {
PenningTrap trap; PenningTrap trap;
trap.add_particle(Particle(1.,40.,arma::vec{1.,2.,3.}, trap.add_particle(
arma::vec{3.,4.,5.})); Particle(1., 40., arma::vec{1., 2., 3.}, arma::vec{3., 4., 5.}));
arma::vec expected{395.58954878,-270.15871624,-57.89115348}; arma::vec expected{395.58954878, -270.15871624, -57.89115348};
arma::vec result = trap.total_force_external(0); arma::vec result = trap.total_force_external(0);
ASSERT(arma_vector_close_to(expected, result), ASSERT(arma_vector_close_to(expected, result),
"Testing the total external force on a particle at " "Testing the total external force on a particle at "
@ -111,23 +108,23 @@ public:
static void test_total_force_particles() static void test_total_force_particles()
{ {
PenningTrap trap; PenningTrap trap;
trap.add_particle(Particle(1.,40.,arma::vec{0.,0.,0.}, trap.add_particle(
arma::vec{0.,0.,0.})); Particle(1., 40., arma::vec{0., 0., 0.}, arma::vec{0., 0., 0.}));
arma::vec expected{0.,0.,0.}; arma::vec expected{0., 0., 0.};
arma::vec result = trap.total_force_particles(0); arma::vec result = trap.total_force_particles(0);
ASSERT(arma_vector_close_to(expected, result), ASSERT(arma_vector_close_to(expected, result),
"Testing the total force of all particles on particle 0 " "Testing the total force of all particles on particle 0 "
"with only a single particle"); "with only a single particle");
trap.add_particle(Particle(1.,40.,arma::vec{1.,0.,0.}, trap.add_particle(
arma::vec{0.,0.,0.})); Particle(1., 40., arma::vec{1., 0., 0.}, arma::vec{0., 0., 0.}));
trap.add_particle(Particle(1.,40.,arma::vec{0.,1.,0.}, trap.add_particle(
arma::vec{0.,0.,0.})); Particle(1., 40., arma::vec{0., 1., 0.}, arma::vec{0., 0., 0.}));
trap.add_particle(Particle(1.,40.,arma::vec{0.,0.,1.}, trap.add_particle(
arma::vec{0.,0.,0.})); Particle(1., 40., arma::vec{0., 0., 1.}, arma::vec{0., 0., 0.}));
expected = arma::vec(3,arma::fill::value(-3473.383325)); expected = arma::vec(3, arma::fill::value(-3473.383325));
result = trap.total_force_particles(0); result = trap.total_force_particles(0);
ASSERT(arma_vector_close_to(expected, result), ASSERT(arma_vector_close_to(expected, result),
"Testing the total force of all particles on particle 0 " "Testing the total force of all particles on particle 0 "
@ -135,7 +132,6 @@ public:
} }
}; };
int main() int main()
{ {
PenningTrapTest::test_external_E_field(); PenningTrapTest::test_external_E_field();

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@ -18,10 +18,10 @@ std::string scientific_format(double d, int width, int prec)
return ss.str(); return ss.str();
} }
std::string scientific_format(const std::vector<double>& v, int width, int prec) std::string scientific_format(const std::vector<double> &v, int width, int prec)
{ {
std::stringstream ss; std::stringstream ss;
for(double elem : v) { for (double elem : v) {
ss << scientific_format(elem, width, prec); ss << scientific_format(elem, width, prec);
} }
return ss.str(); return ss.str();
@ -37,12 +37,8 @@ static void print_message(std::string msg)
} }
} }
void m_assert(bool expr, void m_assert(bool expr, std::string expr_str, std::string f, std::string file,
std::string expr_str, int line, std::string msg)
std::string f,
std::string file,
int line,
std::string msg)
{ {
std::string new_assert(f.size() + (expr ? 4 : 6), '-'); std::string new_assert(f.size() + (expr ? 4 : 6), '-');
std::cout << "\x1B[36m" << new_assert << "\033[0m\n"; std::cout << "\x1B[36m" << new_assert << "\033[0m\n";
@ -54,8 +50,8 @@ void m_assert(bool expr,
else { else {
std::cout << "\x1B[31mFAIL\033[0m\n"; std::cout << "\x1B[31mFAIL\033[0m\n";
print_message(msg); print_message(msg);
std::cout << file << " " << line << ": Assertion \"" std::cout << file << " " << line << ": Assertion \"" << expr_str
<< expr_str << "\" Failed\n\n"; << "\" Failed\n\n";
abort(); abort();
} }
} }
@ -66,7 +62,7 @@ bool arma_vector_close_to(arma::vec &a, arma::vec &b, double tol)
return false; return false;
} }
for (int i=0; i < a.n_elem; i++) { for (int i = 0; i < a.n_elem; i++) {
if (std::abs(a(i) - b(i)) >= tol) { if (std::abs(a(i) - b(i)) >= tol) {
return false; return false;
} }