import math


def gauss(x, mu=0.0, sigma=1.0):
    """
    Return the value of the Gaussian probability function with mean mu
    and standard deviation sigma at the given x value.
    """
    # aus https://introcs.cs.princeton.edu/python/22module/gaussian.py.html
    x = float(x - mu) / sigma
    return math.exp(-x*x/2.0) / math.sqrt(2.0*math.pi) / sigma