gareth

# Code adapted from http://bytes.com/topic/c-sharp/answers/240995-normal-distribution#post980230
module Normdist
  def self.normdist x, mean, std, cumulative
    if cumulative
      phi_around x, mean, std
    else
      tmp = 1/((Math.sqrt(2*Math::PI)*std))
      tmp * Math.exp(-0.5 * ((x-mean)/std ** 2))
    end
  end