golden_ratio_gen.py

from decimal import *
import math

def mem_fib(n, _cache={}):
    '''efficiently memoized recursive function, returns a Fibonacci number'''
    if n in _cache:
        return _cache[n]
    elif n > 1:
        return _cache.setdefault(n, mem_fib(n-1) + mem_fib(n-2))
    return n

getcontext().prec = 200
result = Decimal(mem_fib(601)) / Decimal(mem_fib(600))

wiki_golden_ratio = "1.6180339887498948482045868343656381177203091798057628621354486227052604628189024497072072041893911374847540880753868917521266338622235369317931800607667263544333890865959395829056383226613199282902679"

print result
print wiki_golden_ratio
print str(result) == wiki_golden_ratio

This little test helps prove that the decimal library can handle precision far greater than floating point.