lib/distribution/lognormal/ruby.rb
module Distribution
module LogNormal
module Ruby_
class << self
def pdf(x, u, s)
fail 'x should be > 0 ' if x < 0
(1.0 / (x * s * Math.sqrt(2 * Math::PI))) * Math.exp(-((Math.log(x) - u)**2 / (2 * s**2)))
end
def cdf(x, u, s)
Distribution::Normal.cdf((Math.log(x) - u) / s)
end
end
end
end
end