require File.expand_path(File.dirname(__FILE__)+"/spec_helper.rb")
include ExampleWithGSL
describe Distribution::Beta do

 shared_examples_for "Beta engine" do
   it_only_with_gsl "should return correct pdf" do
      if @engine.respond_to? :pdf
        1.upto(101) do |x|
          a=rand * x
          b=1 + rand * 5
          g=GSL::Ran.beta_pdf(x,a,b)
          @engine.pdf(x,a,b).should be_within(1e-10).of(g)
        end
      else
        pending("No #{@engine}.pdf")
      end
    end

  it_only_with_gsl "should return correct cdf" do
    if @engine.respond_to? :cdf
      # From GSL-1.9.
      tol = 1048576.0*Float::EPSILON
      @engine.cdf(0.0, 1.2, 1.3).should eq(0.0)
      @engine.cdf(1e-100, 1.2, 1.3).should be_within(tol).of(1.34434944656489596e-120)
      @engine.cdf(0.001, 1.2, 1.3).should be_within(tol).of(3.37630042504535813e-4)
      @engine.cdf(0.01, 1.2, 1.3).should be_within(tol).of(5.34317264038929473e-3)
      @engine.cdf(0.1, 1.2, 1.3).should be_within(tol).of(8.33997828306748346e-2)
      @engine.cdf(0.325, 1.2, 1.3).should be_within(tol).of(3.28698654180583916e-1)
      @engine.cdf(0.5, 1.2, 1.3).should be_within(tol).of(5.29781429451299081e-1)
      @engine.cdf(0.9, 1.2, 1.3).should be_within(tol).of(9.38529397224430659e-1)
      @engine.cdf(0.99, 1.2, 1.3).should be_within(tol).of(9.96886438341254380e-1)
      @engine.cdf(0.999, 1.2, 1.3).should be_within(tol).of(9.99843792833067634e-1)
      @engine.cdf(1.0, 1.2, 1.3).should be_within(tol).of(1.0)
    else
      pending("No #{@engine}.cdf")
    end
  end
  it "should return correct p_value" do
    if @engine.respond_to? :p_value
      2.upto(99) do |x|
        a=rand() * x
        b=1 + rand() * 5
        pr=@engine.cdf(x/100.0,a,b)
        @engine.p_value(pr,a, b).should be_within(1e-10).of(x/100.0)
       end
    else
      pending("No #{@engine}.p_value")
    end
  end
end

  describe "singleton" do
    before do
      @engine=Distribution::Beta
    end
    it_should_behave_like "Beta engine"
  end
  
  describe Distribution::Beta::Ruby_ do
    before do
      @engine=Distribution::Beta::Ruby_
    end
    it_should_behave_like "Beta engine"
  end
  if Distribution.has_gsl?
    describe Distribution::Beta::GSL_ do
      before do
        @engine=Distribution::Beta::GSL_
      end
    it_should_behave_like "Beta engine"
    end
  end
  if Distribution.has_java?
    describe Distribution::Beta::Java_ do
      before do
        @engine=Distribution::Beta::Java_
      end
    it_should_behave_like "Beta engine"
    end  
  end
  
end
