kvadratnie formuli

#include <iostream>

using namespace std;

double f2(double x) {
    return x*x;
}
double f3(double x){
    return x*x*x;

}


double integro_l(double (*func) (double), double a, double b, double dx) {
    double S = 0;
    int N = (b - a) / dx;
    for(int i = 0; i < N; i++) {
        S += func(a + i * dx) * dx;
    }

    return S;
}
double integro_m(double (*func) (double), double a, double b, double dx) {
    double S = 0;
    int N = (b - a) / dx;
    for(int i = 0; i < N; i++) {
        S += func(a + (i+0.5) * dx) * dx;
    }

    return S;
}
double integro_r(double (*func) (double), double a, double b, double dx) {
    double S = 0;
    int N = (b - a) / dx;
    for(int i = 0; i < N; i++) {
        S += func(a + (i+1) * dx) * dx;
    }

    return S;
}


int main()
{
    cout << integro_l(f3, -1, 1, 0.1) << endl;
    cout << integro_m(f3, -1, 1, 0.1) << endl;
    cout << integro_r(f3, -1, 1, 0.1) << endl;

}