module Distribution
  module F
  module GSL_
    class << self
      def pdf(x,k1,k2)
        GSL::Ran.fdist_pdf(x.to_f,k1,k2)
      end
      # Return the P-value of the corresponding integral with 
      # k degrees of freedom
      #
      #   Distribution::F.p_value(0.95,1,2)
      def p_value(pr,k1,k2)
        GSL::Cdf.fdist_Pinv(pr.to_f,k1,k2)
      end
      # F cumulative distribution function (cdf).
      # 
      # Returns the integral of F-distribution 
      # with k1 and k2 degrees of freedom
      # over [0, x].
      #   Distribution::F.cdf(20,3,2)
      # 
      def cdf(x, k1, k2)
        GSL::Cdf.fdist_P(x.to_f.to_f,k1,k2)
      end
      end
    end
  end
end
