Produces the nth position of the Fibonacci Squence

fibonacci_squence.py

#!/usr/bin/env python

# Call this script with a number after the script name and it will produce the nth position in the Fibonacci sequence.

# http://www.math.rutgers.edu/~erowland/fibonacci.html

# function fib(n) => return the nth number in fibonacci sequence

# 0, 1, 1, 2, 3, 5, 8

# fib(1) => 0
# fib(2) => 1
# fib(3) => 2
# fib(4) => 3
# fib(5) => 5
# fib(6) => 8

import math
import sys

def calc_fib(position):
    result = (math.pow((1 + math.sqrt(5)), position) - math.pow((1 - math.sqrt(5)), position)) / (math.pow(2, position) * math.sqrt(5))
    return int(result)




def main():
    print calc_fib(int(sys.argv[1]))



if __name__ == '__main__':
    main()