tut5-zad4

#include <iostream>
#include <algorithm>
#include <functional>
#include <cmath>

const double PI{4*atan(1)};


double TrapeznoPravilo (double f (double), double a, double b, int n)
{
    double s1{1/2*f(a)+1/2*f(b)};
    for (int k=1; k<=n-1; k++) {
            s1+=f(a+((b-a)*k)/n);
    }
    return s1*(b-a)/n;
}

int main () {


std::cout<<"Za f-ju sin(x): "<<TrapeznoPravilo(std::sin,0, PI, 1000)<<std::endl;


std::cout<<"Za f-ju x^3: "<<TrapeznoPravilo([] (double x) {return x*x*x; },0, 10, 1000)<<std::endl;

std::cout<<"Za f-ju 1/x: "<<TrapeznoPravilo([] (double x) {return 1/x; },1, 2, 10000);
return 0;

}