Ira 4m lab2

// Ira_4m_lab2.cpp: определ¤ет точку входа дл¤ консольного приложени¤.
//

#include "stdafx.h"
#include <iostream>
#include <string>
#include <vector>
#include <map>
#include <queue>
#include <stack>
#include <deque>
#include <set>
#include <sstream>
#include <fstream>
#include <cmath>
#include <algorithm>
#include <cstdlib>
#include <cstdio>
#include <ctime>
#include "gnuplot_i.hpp"
#include <conio.h>
#include <windows.h>

using namespace std;

typedef vector<pair<double , pair<double , double> > > vpdd;

#define cyrillic setlocale(LC_CTYPE, "rus")

string path1 = "C:\\Users\\Admin\\Documents\\Visual Studio 2010\\Projects\\Ira_4m_lab2\\Ira_4m_lab2\\1.txt";
string path2 = "C:\\Users\\Admin\\Documents\\Visual Studio 2010\\Projects\\Ira_4m_lab2\\Ira_4m_lab2\\2.txt";

inline string DoubleToString(double d){ostringstream strs; strs << d; return strs.str();}

double f(double x , double y);
double g(double x , double y);
void wait();

class Runge_Kutta{
private:
    double h , a , b , x , y;
    int n;

public:
    Runge_Kutta(double N , double mx , double x0 , double y0){
        n = N;
        h = mx / n;
        x = x0;
        y = y0;
    }

    vpdd Order_1(){
        vpdd ans;
        double a = x , b = y;

        ans.push_back(make_pair(0 , make_pair(x , y)));

        for(int i = 1 ; i <= n ; ++i){
            x += h * f(x , y);
            y += h * g(x , y);

            double t = h * i;

            ans.push_back(make_pair(t , make_pair(x , y)));
        }

        x = a , y = b;

        return ans;
    }

    vpdd Order_4(){
        vpdd ans;
        double a = x , b = y;

        ans.push_back(make_pair(0 , make_pair(x , y)));

        vector<double> k(5) , m(5);

        for(int i = 1 ; i <= n ; ++i){
            k[1] = h * f(x , y);
            m[1] = h * g(x , y);

            k[2] = h * f(x + k[1] / 2 , y + m[1] / 2);
            m[2] = h * g(x + k[1] / 2 , y + m[1] / 2);

            k[3] = h * f(x + k[2] / 2 , y + m[2] / 2);
            m[3] = h * g(x + k[2] / 2 , y + m[2] / 2);

            k[4] = h * f(x + k[3] , y + m[3]);
            m[4] = h * g(x + k[3] , y + m[3]);

            x += (k[1] + 2 * (k[2] + k[3]) + k[4]) / 6.0;
            y += (m[1] + 2 * (m[2] + m[3]) + m[4]) / 6.0;

            double t = h * i;

            ans.push_back(make_pair(t , make_pair(x , y)));
        }

        x = a , y = b;

        return ans;
    }
};

double f(double x , double y){
    return (4.0 - 2.5 * y) * x - 0.1 * x * x;
//  return 2 * x - 0.02 * x * y;
}

double g(double x , double y){
    return (1.0 * x - 2.0) * y - 0.1 * y * y;
//  return 0.0002 * x * y - 0.8 * y;
}

int main(){
    double t , n , x , y;
    int ord;
    cout << "T:\n";
    cin >> t;
    cout << "n:\n";
    cin >> n;
    cout << "x(0):\n";
    cin >> x;
    cout << "y(0):\n";
    cin >> y;
    cout << "Order (1 or 4):\n";
    cin >> ord;

    Runge_Kutta rk(n , t , x , y);

    vpdd ans = (ord == 1 ? rk.Order_1() : rk.Order_4());

    FILE * file1 = fopen(&path1[0] , "w");
    FILE * file2 = fopen(&path2[0] , "w");

    pair<double , double> mx1 , mx2;
    mx1 = mx2 = make_pair(DBL_MAX , DBL_MIN);

    for(int i = 0 ; i < ans.size() ; ++i){
        fprintf(file1 , "  %lf   %lf\n" , ans[i].first , ans[i].second.first);
        fprintf(file2 , "  %lf   %lf\n" , ans[i].first , ans[i].second.second);

        mx1.first = min(mx1.first , ans[i].second.first);
        mx1.second = max(mx1.second , ans[i].second.first);

        mx2.first = min(mx2.first , ans[i].second.second);
        mx2.second = max(mx2.second , ans[i].second.second);
    }

    fclose(file1);
    fclose(file2);

    Gnuplot gnu("lines");

    gnu.set_grid();

    int offset = 5;

    string aa = "";
    aa += "set yrange [" + DoubleToString(mx1.first - offset) + ":" + DoubleToString(mx1.second + offset) + "]\n";
    aa += "set y2range [" + DoubleToString(mx2.first - offset) + ":" + DoubleToString(mx2.second + offset) + "]\n";
    aa += "set xrange [0:" + DoubleToString(t) + "]\n";
    aa += "set y2tics\n";
    aa += "set ylabel \"Жертви \"\n";
    aa += "set y2label \"Хижаки \"\n";
    aa += "Жертви = '" + path1 + "'\n";
    aa += "Хижаки = '" + path2 + "'\n";
    string bb = "plot Жертви axes x1y1 with lines , Хижаки axes x1y2 with lines";

    gnu.plot_points(bb , aa);

    wait();

    remove(&path1[0]);
    remove(&path2[0]);

    gnu.remove_tmpfiles();
    return 0;
}

void wait(){
    FlushConsoleInputBuffer(GetStdHandle(STD_INPUT_HANDLE));
    #ifndef FOUT
        cout << endl << "Press any key to continue..." << endl;
    #endif
    _getch();
}