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require File.expand_path(File.dirname(__FILE__) + '/spec_helper.rb')
include ExampleWithGSL
describe Distribution::Binomial do
shared_examples_for 'binomial engine' do
it 'should return correct pdf' do
if @engine.respond_to? :pdf
[10, 100, 1000].each do |n|
[1.quo(4), 1.quo(2), 3.quo(4)].each do |pr|
[0, 1, n / 2, n - 1].each do |x|
exp = Math.binomial_coefficient(n, x) * pr**x * (1 - pr)**(n - x)
obs = @engine.pdf(x, n, pr)
expect(obs).to be_within(1e-5).of(exp), "For pdf(#{x},#{n},#{pr}) expected #{exp}, obtained #{obs}"
end
end
end
else
skip("No #{@engine}.pdf")
end
end
it_only_with_gsl 'should return correct cdf for n<=100' do
if @engine.respond_to? :pdf
[10, 100].each do |n|
[0.25, 0.5, 0.75].each do |pr|
[1, n / 2, n - 1].each do |x|
exp = GSL::Cdf.binomial_P(x, pr, n)
obs = @engine.cdf(x, n, pr)
expect(exp).to be_within(1e-5).of(obs), "For cdf(#{x},#{n},#{pr}) expected #{exp}, obtained #{obs}"
end
end
end
else
skip("No #{@engine}.cdf")
end
end
end
describe 'singleton' do
before do
@engine = Distribution::Binomial
end
it_should_behave_like 'binomial engine'
it { expect(@engine).to respond_to(:exact_pdf) }
it {
pending('No exact_p_value')
expect(@engine).to respond_to(:exact_p_value)
}
it 'exact_cdf should return same values as cdf for n=50' do
pr = rand * 0.8 + 0.1
n = rand(10) + 10
[1, (n / 2).to_i, n - 1].each do |k|
expect(@engine.exact_cdf(k, n, pr)).to be_within(1e-10).of(@engine.cdf(k, n, pr))
end
end
it 'exact_pdf should not return a Float if not float is used as parameter' do
expect(@engine.exact_pdf(1, 1, 1)).to_not be_a(Float)
expect(@engine.exact_pdf(16, 80, 1.quo(2))).to_not be_a(Float)
end
end
describe Distribution::Binomial::Ruby_ do
before do
@engine = Distribution::Binomial::Ruby_
end
it_should_behave_like 'binomial engine'
it 'should return correct cdf for n>100' do
[500, 1000].each do |n|
[0.5, 0.6].each do |pr|
[n / 2].each do |x|
cdf = @engine.exact_cdf(x, n, pr)
p_value = @engine.p_value(cdf, n, pr)
msg = "For p_value(#{cdf},#{n},#{pr}) expected #{x}, obtained #{p_value}"
expect(p_value).to eq(x), msg
end
end
end
end
it 'should return correct p_value for n<=100' do
pending("Can't calculate with precision x using p")
[10, 100].each do |n|
[0.25, 0.5, 0.75].each do |pr|
[n / 2].each do |x|
cdf = @engine.cdf(x, n, pr)
p_value = @engine.p_value(cdf, n, pr)
msg = "For p_value(#{cdf},#{n},#{pr}) expected #{x}, obtained #{p_value}"
expect(p_value).to eq(x), msg
end
end
end
end
end
if Distribution.has_gsl?
describe Distribution::Binomial::GSL_ do
before do
@engine = Distribution::Binomial::GSL_
end
it_should_behave_like 'binomial engine'
end
end
if Distribution.has_java?
describe Distribution::Binomial::Java_ do
before do
@engine = Distribution::Binomial::Java_
end
it_should_behave_like 'binomial engine'
end
end
end
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