Sample_program_ODE/Sample012/main_sim.cpp at master · mino2357/Sample_program_ODE · GitHub

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* RKF78法で二階の常微分方程式を解く．

* テーマ：アレンストーフ軌道．

* 線形代数ライブラリのEigenを使用．

* Boostも使用．

* by みーくん．

#include "ERK.hpp"

#include <iostream>

#include <cmath>

#include <limits>

#include <iomanip>

#include <string>

#include <Eigen/Core>

#include <Eigen/Sparse>

#include <Eigen/Dense>

#include <boost/multiprecision/cpp_dec_float.hpp>

namespace mp = boost::multiprecision;

using multiFloat = mp::cpp_dec_float_100;

//時刻に関するパラメータ

multiFloat dt("1.0e-8");

const multiFloat t_limit("100.0");

const multiFloat RTol("10e-20");

const multiFloat ATol("10e-20");

const multiFloat t_min("10e-40");

const multiFloat t_max("0.1");

//インターバル

constexpr int INTV = 1;

//movie

constexpr int sim = 0;

int main(){

Eigen::Matrix<multiFloat, 4, 1> x(0.994, 0, 0, -2.00158510637908252240537862224);

std::cout << std::fixed << std::setprecision(35);

std::cerr << std::fixed << std::setprecision(35);

multiFloat t{};

mino2357::RKF78<multiFloat> rkf78(ATol, RTol);

for(int i=0; t<t_limit; i++){

if(i%INTV == 0){

//std::cerr << t << " " << mp::log10(dt) << std::endl;

std::cout << t << " " << mp::log10(dt) << " " << x(0,0) << " " << x(1,0) << " " << x(2,0) << " " << x(3,0) << std::endl;

}

rkf78.Integrate(t, dt, x);

}

Sample_program_ODE/Sample012/main_sim.cpp at master · mino2357/Sample_program_ODE · GitHub

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