Source code for monty.fractions

# coding: utf-8
"""
Math functions.
"""
from __future__ import absolute_import, division

try:
    # New Py>=3.5 import
    from math import gcd as pygcd
except ImportError:
    # Deprecated import from Py3.5 onwards.
    from fractions import gcd as pygcd

__author__ = 'Shyue Ping Ong'
__copyright__ = 'Copyright 2013, The Materials Virtual Lab'
__version__ = '0.1'
__maintainer__ = 'Shyue Ping Ong'
__email__ = 'ongsp@ucsd.edu'
__date__ = '8/6/14'


def gcd(*numbers):
    """
    Returns the greatest common divisor for a sequence of numbers.

    Args:
        \*numbers: Sequence of numbers.

    Returns:
        (int) Greatest common divisor of numbers.
    """
    n = numbers[0]
    for i in numbers:
        n = pygcd(n, i)
    return n


def lcm(*numbers):
    """
    Return lowest common multiple of a sequence of numbers.

    Args:
        \*numbers: Sequence of numbers.

    Returns:
        (int) Lowest common multiple of numbers.
    """
    n = 1
    for i in numbers:
        n = (i * n) // gcd(i, n)
    return n


def gcd_float(numbers, tol=1e-8):
    """
    Returns the greatest common divisor for a sequence of numbers.
    Uses a numerical tolerance, so can be used on floats

    Args:
        numbers: Sequence of numbers.
        tol: Numerical tolerance

    Returns:
        (int) Greatest common divisor of numbers.
    """

    def pair_gcd_tol(a, b):
        """Calculate the Greatest Common Divisor of a and b.

        Unless b==0, the result will have the same sign as b (so that when
        b is divided by it, the result comes out positive).
        """
        while b > tol:
            a, b = b, a % b
        return a

    n = numbers[0]
    for i in numbers:
        n = pair_gcd_tol(n, i)
    return n