code: def log_normal_cdf(x, median=1, sigma=1):
      
      return normal_cdf(numpy.log(x), mu=numpy.log(median), sigma=sigma)
docs: Cumulative Log Normal Distribution Function.
  
      :param x: scalar or array of real numbers.
      :type x: numpy.ndarray, float
  
      :param median: Median (exp(mean of log(x)). Default 1.
      :type median: float
  
      :param sigma: Log normal standard deviation. Default 1.
      :type sigma: float
  
      :returns: An approximation of the cdf of the normal.
      :rtype: numpy.ndarray
  
      .. note::
          CDF of the normal distribution is defined as
          \frac12 [1 + erf(\frac{x - \mu}{\sigma \sqrt{2}})], x \in \R
  
          Source: http://en.wikipedia.org/wiki/Normal_distribution