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example.py
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example.py
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"""
Multiple Return
Copyright (C) 2014 Gregory S. Bell
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
An example of a multiple return function.
Sometimes you just want the greatest common denominator of the two integers
>>> extended_gcd(45, 99)
9
But sometimes you want more information (like for RSA)
>>> values(extended_gcd(45, 99))
GcdResult(gcd=9, bezout_coefficients=(-2, 1), quotients=(-5, -11))
"""
import collections
from multiplereturn import *
@multiplereturn
def extended_gcd(a, b):
"""Returns the greatest common denominator of its arguments, the Bezout coefficients, and the quotients
:param a: an integer
:param b: an integer
"""
gcd_result = collections.namedtuple('GcdResult', ['gcd', 'bezout_coefficients', 'quotients'])
s, old_s = 0, 1
t, old_t = 1, 0
r, old_r = b, a
while r != 0:
quotient = old_r // r
(old_r, r) = (r, old_r - quotient * r)
(old_s, s) = (s, old_s - quotient * s)
(old_t, t) = (t, old_t - quotient * t)
return gcd_result(old_r, (old_s, old_t), (t, -s))