Insane Decimal Math -- 624 digits of Phi

phi.py

""" Really exercise the Decimal Math processor.

Calculates two weird identities of the irrational number Phi using an insane number of digits.
Phi**2 + Phi**-2 == 3
8 * Phi**2 - Phi**6 == 3
"""
from __future__ import print_function

digits = ("1.61803398874989484820458683436563811772030917980576286213544862270526046281890" 
"244970720720418939113748475408807538689175212663386222353693179318006076672635" 
"443338908659593958290563832266131992829026788067520876689250171169620703222104" 
"321626954862629631361443814975870122034080588795445474924618569536486444924104" 
"432077134494704956584678850987433944221254487706647809158846074998871240076521" 
"705751797883416625624940758906970400028121042762177111777805315317141011704666" 
"599146697987317613560067087480710131795236894275219484353056783002287856997829" 
"778347845878228911097625003026961561700250464338243776486102838312683303724292")

import decimal

def compress_print(d):
    s = str(d)
    reps = 0
    digit = s[2]
    i = 3
    while s[i] == digit:
        i += 1
        reps += 1
    return '{} and {} more "{}"s then {}'.format(s[:3], reps, digit, s[i:])

with decimal.localcontext() as context:
    context.prec = len(digits)-1
    phi = decimal.Decimal(digits)
    id1 = phi**2 + phi**-2    # Identity 1 (== 3)
    id2 = 8 * phi**2 - phi**6 # Identity 2 (== 3)
    print('Phi is {} digits long, {}...{}'.format(len(digits) - 1, digits[:5], digits[-5:]))
    print('The 1st identity is', compress_print(id1))
    print('The 2nd identity is', compress_print(id2))
    print('Equal?', id1 == id2)
    print('The difference is=', id2 - id1)