#!/usr/bin/env python3
import numpy as np
import timeit


def fact_rec(n):
    # y = fact_rec(n) berechnet die Fakultät von n als
    # fact_rec(n) = n * fact_rec(n - 1) mit fact_rec(0) = 1
    # Fehler, falls n <0 oder nicht ganzzahlig
    if n < 0 or np.trunc(n) != n:
        raise Exception('The factorial is defined only for positive integers')
    if n <= 1:
        return 1
    else:
        return n*fact_rec(n-1)


def fact_for(n):
    fak = 1
    for num in range(n):
        fak *= n
        n -= 1
    return fak


if __name__ == "__main__":
    t1 = timeit.repeat(
        "fact_rec(500)",
        "from __main__ import fact_rec",
        number=100)
    print(t1)

    t2 = timeit.repeat(
        "fact_for(500)",
        "from __main__ import fact_for",
        number=100)
    print(t2)