def gaussian(x, mu, sig):
    """return normal distribution at point x.

   :math:`f(x;\\mu,\\sigma) = \\frac{1}{\\sigma\\sqrt{2\\pi}}e^{-\\frac{(x-\\mu)^2}{2\\sigma^2}}`

   :param x: x
   :type x: float
   :param mu: :math:`\\mu`
   :type mu: float
   :param sigma: :math:`\\sigma`
   :type sigma: float
   :returns: :math:`f(x;\\mu,\\sigma)`
   :rtype: float

   :Example:

   >>> from westpy import * 
   >>> gaussian(1.0,2.0,3.0)
   """
    import numpy as np
    return 1.0 / (np.sqrt(2.0 * np.pi) * sig) * np.exp(-np.power((x - mu) /
        sig, 2.0) / 2)
