task2

#include <iostream>
#include <math.h>

using namespace std;

double fun(double x);
double integral(double start, double end, double epsil, double (*f) (double));

int main()
{
    cout << "Please, enter start and end: ";
    double a, b, epsil, result;
    cin >> a >> b;
    cout << "Please, enter epsil: ";
    cin >> epsil;
    result = integral(a, b, epsil, fun);
    cout << "Integral = " << result << endl;
    return 0;
}

double fun(double s)
{
    double x;
    if ((s>=0)&&(s<=1))
        x = s;
    else if ((s>=1)&&(s<=2))
        x = 2-s;
    else x = 0;
    return cos(s)*x;
}

double integral(double start, double end, double epsil, double (*f) (double))
{
    double s = 0;
    for (double x = start; x<=end; x+=epsil)
        s += fabs(f(x));
    return s*epsil;
}