FindMI.py

#!/usr/bin/env python

## FindMI.py

import sys

if len(sys.argv) != 3:  
    sys.stderr.write("Usage: %s   <integer>   <modulus>\n" % sys.argv[0]) 
    sys.exit(1) 

NUM, MOD = int(sys.argv[1]), int(sys.argv[2])

def MI(num, mod):
    '''
    This function uses ordinary integer arithmetic implementation of the
    Extended Euclid's Algorithm to find the MI of the first-arg integer
    vis-a-vis the second-arg integer.
    '''
    NUM = num; MOD = mod
    x, x_old = 0L, 1L
    y, y_old = 1L, 0L
    while mod:
        q = num // mod
        num, mod = mod, num % mod
        x, x_old = x_old - q * x, x
        y, y_old = y_old - q * y, y
    if num != 1:
        print("\nNO MI. However, the GCD of %d and %d is %u\n" % (NUM, MOD, num))
    else:
        MI = (x_old + MOD) % MOD
        print("\nMI of %d modulo %d is: %d\n" % (NUM, MOD, MI))

MI(NUM, MOD)