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require File.expand_path(File.dirname(__FILE__) + '/spec_helper.rb')
include ExampleWithGSL
describe Distribution::Poisson do
shared_examples_for 'poisson engine(with rng)' do
it 'should return correct rng' do
# The expected rng output when 1 is set as the seed value
exp_means = [1, 2, 2, 3, 4, 5, 6, 7, 8, 9]
lambda_val = rand(10) + 1
exp_mean = exp_means[lambda_val - 1]
seed = 1
rng = @engine.rng(lambda_val, seed)
samples = 100
sum = 0
samples.times do
v = rng.call
sum += v
end
mean = sum / samples
expect(mean.to_i).to be_within(1e-10).of(exp_mean)
end
end
shared_examples_for 'poisson engine(with rng)' do
it 'rng with a specified seed should be reproducible' do
seed = 1
rng1 = @engine.rng(3, seed)
rng2 = @engine.rng(3, seed)
expect((rng1.call)).to eq(rng2.call)
end
end
shared_examples_for 'poisson engine' do
it 'should return correct pdf' do
if @engine.respond_to? :pdf
[0.5, 1, 1.5].each {|l|
1.upto(5) {|k|
expect(@engine.pdf(k, l)).to be_within(1e-10).of((l**k * Math.exp(-l)).quo(Math.factorial(k)))
}
}
else
pending("No #{@engine}.pdf")
end
end
it_only_with_gsl 'should return correct cdf' do
if @engine.respond_to? :cdf
[0.5, 1, 1.5, 4, 10].each {|l|
1.upto(5) {|k|
expect(@engine.cdf(k, l)).to be_within(1e-10).of(GSL::Cdf.poisson_P(k, l))
}
}
else
pending("No #{@engine}.cdf")
end
end
it 'should return correct p_value' do
pending('No exact p_value')
if @engine.respond_to? :p_value
[0.1, 1, 5, 10].each {|l|
1.upto(20) {|k|
pr = @engine.cdf(k, l)
expect(@engine.p_value(pr, l)).to eq(k)
}
}
else
skip("No #{@engine}.p_value")
end
end
end
describe 'singleton' do
before do
@engine = Distribution::Poisson
end
it_should_behave_like 'poisson engine'
end
describe Distribution::Poisson::Ruby_ do
before do
@engine = Distribution::Poisson::Ruby_
end
it_should_behave_like 'poisson engine'
end
if Distribution.has_gsl?
describe Distribution::Poisson::GSL_ do
before do
@engine = Distribution::Poisson::GSL_
end
it_should_behave_like 'poisson engine'
end
end
if Distribution.has_java?
describe Distribution::Poisson::Java_ do
before do
@engine = Distribution::Poisson::Java_
end
it_should_behave_like 'poisson engine'
it 'should return correct cdf' do
[0.5, 1, 1.5, 4, 10].each {|l|
1.upto(5) {|k|
expect(@engine.cdf(k, l)).to be_within(1e-10).of(Distribution::Poisson::Ruby_.cdf(k, l))
}
}
end
end
end
end
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