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Contents
module Statistics
module Distribution
class Beta
attr_accessor :alpha, :beta
def initialize(alp, bet)
self.alpha = alp.to_f
self.beta = bet.to_f
end
def cumulative_function(value)
Math.incomplete_beta_function(value, alpha, beta)
end
def density_function(value)
return 0 if value < 0 || value > 1 # Density function defined in the [0,1] interval
num = (value**(alpha - 1)) * ((1 - value)**(beta - 1))
den = Math.beta_function(alpha, beta)
num/den
end
def mode
return unless alpha > 1 && beta > 1
(alpha - 1)/(alpha + beta - 2)
end
def mean
return if alpha + beta == 0
alpha / (alpha + beta)
end
end
end
end
Version data entries
9 entries across 9 versions & 1 rubygems