#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
 
double trapez(double(*f)(double), double a, double b, double eps)
{
    double old_i = 0, new_i = old_i+2*eps;
    for(unsigned int n = 1; abs(new_i-old_i) > eps; n *= 2)
    {
        old_i = new_i;
        double h = (b-a)/n, s = -(f(a) + f(b))/2;
        for(int i = 0; i <= n; ++i)
            s += f(a + i*h);
        new_i = s*h;
    }
    return new_i;
}
 
double y(double x) { return sin(x)*cos(x*x); }
 
int main(int argc, char * argv[])
{
    cout << setprecision(10) << trapez(y,0,5,1e-10) << endl;
}
 

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