#!/usr/bin/python3
# Integration with the trapezium rule

def int_trapez(f, a, b, N):
    h = (b - a) / N            # step width
    result = f(a)/2 + f(b)/2   # contributions of the boundary points
    for k in range(1, N):      # add to this the contributions of the interior points
        xk = a + k*h
        result += f(xk)
    result *= h
    return result