//倒单摆(Inverted pendulum)c++
#include<stdio.h>
#include<iomanip>
#include <iostream>
#include <cmath>
//#define PI 3.1415926
#define PI 0x3.243F6A8885A3p+0
#define PI16 0x3.243F6A8885A308D313198A2E03707344A4093822299F31D0082EFA98EC4E6C89p+0
long double fPi0x=atan(1)*4.0;
using namespace std;
class pendulum
{
public:
double m; //摆杆的质量
double l; //摆杆的长度
double g; //重力加速度
double t; //时间
double theta;//摆杆的角度
pendulum();
pendulum(double m, double l, double g, double t, double theta);
double get_theta();
double get_theta_dot();
void set_theta_dot(double theta_dot);
void calculate_theta(double t);
private:
double theta_dot;//摆杆的角速度
};
pendulum::pendulum()
{
m = 1.0;
l = 1.0;
g = 9.8;
t = 0.0;
theta = 0.0;
theta_dot = 0.0;
}
pendulum::pendulum(double m, double l, double g, double t, double theta)
{
this->m = m;
this->l = l;
this->g = g;
this->t = t;
this->theta = theta;
theta_dot = 0.0;
}
double pendulum::get_theta()
{
return theta;
}
double pendulum::get_theta_dot()
{
return theta_dot;
}
void pendulum::set_theta_dot(double theta_dot)
{
this->theta_dot = theta_dot;
}
void pendulum::calculate_theta(double t)
{
double a = g / l;
theta = theta + theta_dot * t + 0.5 * a * t * t;
theta_dot = theta_dot + a * t;
if (theta >= 2 * PI)
{
theta = theta - 2 * PI;
}
else if (theta < 0)
{
theta = theta + 2 * PI;
}
this->t = t;
}
int main()
{
std::cout << std::setprecision(100);
std::cout<< fPi0x<<std::endl;
std::cout<<PI<<std::endl;
std::cout<<PI16<<std::endl;
pendulum p(1.0, 1.0, 9.8, 0.0, 0.0);
long double theta, theta_dot;
std::cout << std::setprecision(12);
for (int i = 0; i < 10; i++)
{//220for
theta = p.get_theta();
theta_dot = p.get_theta_dot();
p.calculate_theta(0.1);
// printf("t=%ll",p.t);
cout << "t = " << p.t << ", theta = " << theta << " rad, theta_dot = " << theta_dot << " rad/s" << endl;
// printf(",theta=%ll",theta);
}//220for
return 0;
}//10main