Метод Рунге-Кутта второго порядка

#include "stdafx.h"
#include
using namespace std;
const double eps = 1e-3;
 
double k = 0;
 
double f(double x)
{
return pow(x, 5) - pow(x, 3) - 3;
}
double runge(double X, double Y)
{
return cos(k*X + Y) + (3 * (X-Y));
}
int main()
{
double a, b, c;
double dy;
double n = 100;
double h;
double k1, k2, k3, k4;
double *X = new double[n];
double *Y = new double[n];
cout << "Delenie otrezka popolam" << endl << endl;
cout << "Vvedite a: "; cin >> a; cout << endl;
cout << "Vvedite b: "; cin >> b; cout << endl;
do
{
c = (a + b) / 2;
if (f(b) * f(c) < 0)
a = c;
else
b = c;
cout << "c = " << c << endl;
} while (abs(f(c)) > eps);
cout << "c = " << c << endl << endl;
k = c;
cout << "k = " << k << endl << endl;
{
cout << "Runge-Kutta 2 poryadka" << endl << endl;
cout << "Vvedite a: "; cin >> a; cout << endl;
cout << "Vvedite b: "; cin >> b; cout << endl;
cout << "Vvedite n: "; cin >> n; cout << endl;
 
h = 0,1;
 
cout << "Shag = " << h; cout << endl; cout << endl;
 
X[0] = a; Y[0] = 0.0;
 
for (int i = 1; i <= n; i++)
{
X = a + i*h;
}
for (int i = 1; i <= n; i++)
{
cout << "X[" << i << "]=" << X << " " << endl;
}
cout << endl; cout << endl;
 
for (int i = 1; i <= n; i++)
{
k1 = Y(i)+h/2*runge(X, Y);
cout << "k1 = " << k1 << " " << endl;
k2 = h*runge(X + h / 2, Y + k1 / 2);
cout << "k2 = " << k2 << " " << endl;
k3 = h*runge(X + h / 2, Y + k2 / 2);
cout << "k3 = " << k3 << " " << endl;
k4 = h*runge(X + h, Y + k3);
cout << "k4 = " << k4 << " " << endl;
dy = (k1 + 2 * k2 + 2 * k3 + k4) * (1.00 / 6.00);
cout << "dy = " << dy << " " << endl;
Y = Y + dy; cout << "Y[" << i << "]= " << Y << " " << endl;
}
return 0;
}
 
}

#include "stdafx.h"
#include <iostream>
#include <cmath>
 
using namespace std;
 
double f(double x)
{
    return pow(x, 5) - pow(x, 3) - 3.;
}
 
double runge(double X, double Y, double k)
{
    return cos(k*X + Y) + (3 * (X - Y));
}
 
int main()
{
    double a, b, c;
    double h = 0.1;
    double k;
    double k1, k2, k3, k4;
    cout << "Delenie otrezka popolam" << endl << endl;
    cout << "Vvedite a: "; cin >> a; cout << endl;
    cout << "Vvedite b: "; cin >> b; cout << endl;
 
    do
    {
        c = (a + b) / 2;
        if (f(b) * f(c) < 0)
            a = c;
        else
            b = c;
    } while (abs(f(c)) > 0.0001);
 
    k = c;
    cout << "k = " << k << endl << endl;
    
    double x = 0., y = 0.;
 
    do {
        std::cout << " x = " << x << "     " << " y = " << y << std::endl;
        k3 = x + h;
        k1 = runge(x, y, k);
        k4 = y + h*k1;
        k2 = runge(k3, y + h*k1, k);
        y += h / 2.*(k1 + k2);
        x += h;
    //  std::cout << " k1 = " << k1 << "  " << "x+h = " << k3 << "   " << "y+h*k1 =" << k4 << "   " << " k2 = " << k2 << std::endl;
    //  std::cout << " ------------------------------------- " << std::endl;
    } while (x < 1.);
    system("pause");
}