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cosmo-replay/scattering_experiment.cpp

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C++
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#include <array>
#include <atomic>
#include <Eigen/Geometry>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <mutex>
#include <random>
#include <string>
#include <thread>
#include <time.h> // We just want to print the timestamp
#include <unistd.h>
#include "loadtxt.h"
using double3 = Eigen::Vector3d;
using Generator = std::default_random_engine;
// Our units are {kiloparsec, solar mass, gigayear}
constexpr double G = 4.498317481097514e-06;
void integrate(const std::array<double,6> y0, const double t_max, const double stride_size, double y[]);
std::string git_version()
{
std::string result;
std::ifstream git_log(".git/logs/HEAD");
if (git_log) {
std::string prev_line, line;
getline(git_log, prev_line);
while (getline(git_log, line)) {
prev_line = line;
}
if (prev_line.length() > 51) result = prev_line.substr(41, 10);
else result = "UNKNOWN";
} else result = "UNKNOWN";
return result;
}
std::string iso_time(std::chrono::system_clock::time_point time)
{
auto time_c = std::chrono::system_clock::to_time_t(time);
auto timeinfo = gmtime(&time_c);
char time_string[256];
strftime(time_string,256,"%FT%TZ", timeinfo);
return std::string(time_string);
}
class Acceptor {
// This is a base class for functors that accept or decline the final state of the orbit
public:
virtual bool operator()(const double w[6]) const = 0;
virtual void output_information(std::ostream& stream) const = 0;
};
class In_box_cyl : public Acceptor {
public:
In_box_cyl(const double pos_tol, const double vel_tol, const double3 target_pos, const double3 target_vel)
: pos_tol(pos_tol), vel_tol(vel_tol)
{
target_d = sqrt(target_pos[0]*target_pos[0] + target_pos[1]*target_pos[1]);
target_z = target_pos[2];
target_vd = (target_pos[0]*target_vel[0] + target_pos[1]*target_vel[1])/target_d;
target_vt = (target_pos[0]*target_vel[1] - target_pos[1]*target_vel[0])/target_d;
target_vz = target_vel[2];
}
bool operator()(const double w[6]) const override
{
double d = sqrt(w[0]*w[0] + w[1]*w[1]);
double z = w[2];
double vd = (w[0]*w[3] + w[1]*w[4])/d;
double vt = (w[0]*w[4] - w[1]*w[3])/d;
double vz = w[5];
if (((z<0)&&(target_z>0)) || ((z>0)&&(target_z<0))) { // Flip up-down
z = -z;
vz = -vz;
}
if (((vt<0)&&(target_vt>0)) || ((vt>0)&&(target_vt<0))) { // Flip left-right
vt = -vt;
}
return (abs(d - target_d) < pos_tol)
&& (abs(z - target_z) < pos_tol)
&& (abs(vd - target_vd) < vel_tol)
&& (abs(vt - target_vt) < vel_tol)
&& (abs(vz - target_vz) < vel_tol);
}
void output_information(std::ostream& stream) const override
{
stream.setf(std::ios::scientific);
stream << "# Acceptor type: box in cylindrical coordinates\n";
stream << "# Acceptor parameters:\n";
stream << "# pos_tol = " << std::setw(13) << pos_tol << '\n';
stream << "# vel_tol = " << std::setw(13) << vel_tol << '\n';
stream << "# target_d = " << std::setw(13) << target_d << '\n';
stream << "# target_z = " << std::setw(13) << target_z << '\n';
stream << "# target_vd = " << std::setw(13) << target_vd << '\n';
stream << "# target_vt = " << std::setw(13) << target_vt << '\n';
stream << "# target_vz = " << std::setw(13) << target_vz << '\n';
}
private:
double pos_tol, vel_tol;
double target_d, target_z, target_vd, target_vt, target_vz;
};
class Accept_all : public Acceptor {
public:
Accept_all() = default;
bool operator()(const double w[6]) const override
{
return true;
}
void output_information(std::ostream& stream) const override
{
stream << "# Acceptor type: accept all\n";
}
};
////////////////////////////////////////////////////////////////////////////////////////////////////////////
class Match_data : public Acceptor {
public:
Match_data() :
data(Loadtxt("Peter_7D.txt.input", {2, 3, 4, 5, 6, 7}, 3).get_cols()),
n(data[0].size()),
tolerance(0.1)
{
constexpr double pc_to_kpc = 0.001;
for (unsigned i = 0; i < n; i++) {
data[0][i] *= pc_to_kpc;
data[1][i] *= pc_to_kpc;
data[2][i] *= pc_to_kpc;
}
constexpr double kms_to_kpcGyr = 1.0226911647958985;
for (unsigned i = 0; i < n; i++) {
data[3][i] *= kms_to_kpcGyr;
data[4][i] *= kms_to_kpcGyr;
data[5][i] *= kms_to_kpcGyr;
}
}
bool operator()(const double w[6]) const override
{
for (unsigned i = 0; i < n; i++) {
unsigned k;
for (k = 0; k < 6; k++) {
if (abs((w[k] - data[k][i])/w[k]) > tolerance) break;
}
if (k==6) return true;
}
return false;
}
void output_information(std::ostream& stream) const override
{
stream << "# Acceptor type: match data\n";
stream << "# tolerance = " << std::setw(13) << tolerance << '\n';
}
private:
std::vector<std::vector<double>> data;
unsigned n;
double tolerance;
};
class Initial_conditions {
public:
virtual std::array<double,6> operator()(Generator& generator) const = 0;
virtual void output_information(std::ostream& stream) const = 0;
};
class Uniform_sphere_escape_velocity_cutoff : public Initial_conditions {
public:
Uniform_sphere_escape_velocity_cutoff(const double r_max, const double rho_0, const double b)
: r_max(r_max),
rho_0(rho_0),
b(b),
uniform_distribution(std::uniform_real_distribution<double>(0, 1))
{}
std::array<double,6> operator()(Generator& generator) const override
{
std::array<double,6> result;
double r = pow(uniform_distribution(generator), 1./3.)*r_max;
double cos_theta = uniform_distribution(generator)*2-1;
double sin_theta = sqrt(1 - cos_theta*cos_theta);
double phi = uniform_distribution(generator)*2*M_PI;
result[0] = r*cos(phi)*sin_theta;
result[1] = r*sin(phi)*sin_theta;
result[2] = r*cos_theta;
double potential = nfw_potential(r);
if (potential > 0) throw std::runtime_error("Cannot deal with a positive potential");
double v_max = sqrt(-2*potential);
double v_magnitude;
do {
for (int i=3; i<6; i++) result[i] = uniform_distribution(generator);
v_magnitude = sqrt(result[3]*result[3]+result[4]*result[4]+result[5]*result[5]);
} while (v_magnitude >= v_max);
return result;
}
void output_information(std::ostream& stream) const override
{
stream.setf(std::ios::scientific);
stream << "# Initial conditions type: uniform sphere with escape velocity cutoff\n";
stream << "# Initial conditions parameters:\n";
stream << "# r_max = " << std::setw(13) << r_max << '\n';
}
private:
inline double nfw_potential(double r) const
{
return -4*M_PI*G*rho_0*b*b*b*log1p(r/b)/r;
}
double r_max, rho_0, b;
mutable std::uniform_real_distribution<double> uniform_distribution;
};
class Box_initial_conditions : public Initial_conditions {
public:
Box_initial_conditions(double x_max, double v_max)
: x_max(x_max), v_max(v_max)
{
position_distribution = std::uniform_real_distribution<double>(-x_max, x_max);
velocity_distribution = std::uniform_real_distribution<double>(-v_max, v_max);
}
std::array<double,6> operator()(Generator& generator) const override
{
std::array<double,6> result;
for (unsigned i=0; i<3; i++) result[i] = position_distribution(generator);
for (unsigned i=3; i<6; i++) result[i] = velocity_distribution(generator);
return result;
}
void output_information(std::ostream& stream) const override
{
stream.setf(std::ios::scientific);
stream << "# Initial conditions type: uniform box\n";
stream << "# Initial conditions parameters:\n";
stream << "# x_max = " << std::setw(13) << x_max << '\n';
stream << "# v_max = " << std::setw(13) << v_max << '\n';
}
private:
double x_max, v_max;
mutable std::uniform_real_distribution<double> position_distribution, velocity_distribution;
};
class Scattering_experiment {
public:
Scattering_experiment(const std::string& file_name, const double t_max, const unsigned long long n_experiments, const Initial_conditions& initial_conditions, const Acceptor& accept)
: n_experiments(n_experiments),
t_max(t_max),
accept(accept),
initial_conditions(initial_conditions),
start_time(std::chrono::system_clock::now()),
file(std::ofstream(file_name)),
n_threads(std::thread::hardware_concurrency())
{
const unsigned long time_count = start_time.time_since_epoch().count();
const unsigned long big_prime = 840580612873L;
unique_id = time_count + big_prime*getpid(); // TODO hash it
file.setf(std::ios::scientific | std::ios::right);
file.precision(16);
}
~Scattering_experiment() {
file.close();
}
void set_concurrency(int n_threads)
{
this->n_threads = n_threads;
}
void write_header()
{
file << "#############################################\n";
file << "# Cosmological replay scattering experiment #\n";
file << "#############################################\n";
file << "# Time: " << iso_time(start_time) << '\n';
file << "# Last Git commit: " << git_version() << '\n';
char hostname[256];
gethostname(hostname, 256);
file << "# Hostname: " << hostname << '\n';
file << "# PID: " << getpid() << '\n';
file << "# Unique identifier: " << unique_id << '\n';
file << "# Concurrency: " << n_threads << '\n';
initial_conditions.output_information(file);
accept.output_information(file);
file.flush();
// TODO information about galaxy model
}
void thread_task(int tid)
{
auto thread_begin_time = std::chrono::system_clock::now();
auto report_interval = std::chrono::seconds(report_interval_seconds);
auto next_report_time = thread_begin_time + report_interval;
std::default_random_engine generator(unique_id + tid);
while (counter < n_experiments) {
for (int i=0; i<bunch_size; i++) {
auto ic = initial_conditions(generator);
double y[12];
integrate(ic, t_max, t_max, y);
if (accept(y+6)) {
std::lock_guard<std::mutex> lock(mtx);
for (int j=0; j<12; j++) file << std::setw(24) << y[j];
file << std::endl;
}
}
counter += bunch_size;
if (tid == 0) {
auto now = std::chrono::system_clock::now();
if (now >= next_report_time) {
std::lock_guard<std::mutex> lock(mtx);
file << "# " << iso_time(now) << " counter = " << counter << std::endl;
next_report_time = now + report_interval;
}
}
}
}
void launch()
{
counter = 0;
for (int tid=0; tid<n_threads; tid++) {
threads.push_back(std::thread(&Scattering_experiment::thread_task, this, tid));
}
for (auto& t : threads) {
t.join();
}
std::cout << counter << '\n';
}
int n_threads = 1;
int bunch_size = 256;
int report_interval_seconds = 300;
std::chrono::system_clock::time_point start_time;
std::ofstream file;
std::mutex mtx;
std::vector<std::thread> threads;
std::atomic<unsigned long long> counter;
unsigned long long n_experiments;
unsigned long unique_id;
double t_max;
const Acceptor& accept;
const Initial_conditions& initial_conditions;
};
int main()
{
std::cout << "Hi\n";
const double t_max = 11.65551390; // Gyr
Uniform_sphere_escape_velocity_cutoff uniform_sphere_escape_velocity_cutoff(75, 1.82777387E+07, 9.86242602E+00);
auto zzzzz = Match_data();
Scattering_experiment scattering_experiment("results.dat", t_max, 1024*1024*16, uniform_sphere_escape_velocity_cutoff, std::ref(zzzzz));
scattering_experiment.set_concurrency(80);
scattering_experiment.write_header();
scattering_experiment.launch();
std::cout << "Bye\n";
return 0;
}
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