семестровая 2

#include <iostream>
using namespace std;
const double PI = 3.14;
const int m = 6;
const double e = 0.3;
double cos(double x)
{
    double t = 1.0;
    double s = 0.0;
    int n = 1;

    do
    {
        s+= t;
        t *= -1.0 * x * x / ((2 * n - 1) * (2 * n));
        n++;
    } while (fabs(t) > 0.00001);

    return s;
}
double function1(double x)
{
    double psi;
    psi = cos(x)*cos(x);


    return(psi);
}
double function2(double x)
{
    double  fi;

    fi = (2.7*x) / (5.7 - 0.9*x + x*x);

    return(fi);
}
double F(double x, double t)
{
    return function2(x)*function1(x + t / (1 + x*x));
}
double integral(double a, double b, double t)
{
    double h, Jn, J2n;
    int i;
    int n = 1;
    do
    {
        Jn = 0;
        h = (b - a) / n;
        for(int i = 1; i < n; i++)
        {
            Jn += F(a + i*h, t);
        }
        Jn += 0.5*(F(a, t) + F(b, t));
        Jn = Jn*h;
        J2n = 0;
        h = (b - a) / (2 * n);
        for (int i = 1; i <2*n; i++)
        {
            J2n += F(a + i*h, t);
        }
        J2n += 0.5*(F(a, t) + F(b, t));
        J2n = J2n*h;
        n++;
    }
    while (fabs(J2n - Jn)>e);
    return J2n;
}
int  main()
{
    int i;
    double t[m],y[m];
    for (int i = 0; i < m; i++)
    {
        cout << "enter t -2,6 -1,8 -0,2 0,7 1,6 2,5";
        cin >> t[i];
    }
    for (i = 0; i < m; i++)
    {
        y[i] = integral(-2, 0, t[i]);
        cout << " integral = " << y[i] << endl;
    }

    system("pause");
    return 0;
}