Mapytex/pymath/calculus/arithmetic.py

46 lines
812 B
Python

#!/usr/bin/env python
# encoding: utf-8
__all__ = ['gcd']
def gcd(a, b):
"""Compute gcd(a,b)
:param a: first number
:param b: second number
:returns: the gcd
"""
pos_a, _a = (a >= 0), abs(a)
pos_b, _b = (b >= 0), abs(b)
gcd_sgn = (-1 + 2 * (pos_a or pos_b))
if _a > _b:
c = _a % _b
else:
c = _b % _a
if c == 0:
return gcd_sgn * min(_a, _b)
elif _a == 1:
return gcd_sgn * _b
elif _b == 1:
return gcd_sgn * _a
else:
return gcd_sgn * gcd(min(_a, _b), c)
if __name__ == '__main__':
print(gcd(3, 15))
print(gcd(3, 15))
print(gcd(-15, -3))
print(gcd(-3, -12))
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