code: def GaussianCdfInverse(p, mu=0, sigma=1):
      
      x = ROOT2 * erfinv(2 * p - 1)
      return mu + x * sigma
docs: Evaluates the inverse CDF of the gaussian distribution.
  
      See http://en.wikipedia.org/wiki/Normal_distribution#Quantile_function  
  
      Args:
          p: float
  
          mu: mean parameter
          
          sigma: standard deviation parameter
                  
      Returns:
          float