Python script to compute factorials.

calc_factorial.py

#! /usr/local/bin/python3.6
"""
Computation of factorials
"""
import sys
import traceback


class CalcFactorial:
    L  = 64                 # Digits of computation
    L2 = int((L + 7 ) / 8)  # Length of list
    N  = 49                 # Number of computation

    def compute(self):
        """ Computation of factorials """
        try:
            s = [0 for _ in range(self.L2)]
            s[-1] = 1
            for k in range(1, self.N + 1):
                s = self.__long_mul(s, k)
                self.__display(k, s)
        except Exception as e:
            raise

    def __long_mul(self, a, b):
        """ Computation of long * short

        :param  list a
        :param  list b
        :return list z
        """
        try:
            z = [0 for _ in range(self.L2)]
            carry = 0
            for i in reversed(range(self.L2)):
                w = a[i]
                z[i] = (w * b + carry) % 100000000
                carry = int((w * b + carry) / 100000000)
            return z
        except Exception as e:
            raise

    def __display(self, k, s):
        """ Display

        :param int  k
        :param list s
        """
        try:
            print("{:2d}!=".format(k), end="")
            for i in range(0, self.L2):
                print("{:08d}".format(s[i]), end="")
            print()
        except Exception as e:
            raise


if __name__ == '__main__':
    try:
        obj = CalcFactorial()
        obj.compute()
    except Exception as e:
        traceback.print_exc()
        sys.exit(1)