Module: Distribution::Binomial::Ruby_
- Defined in:
- lib/distribution/binomial/ruby.rb
Class Method Summary collapse
-
.cdf(k, n, pr) ⇒ Object
TODO: Use exact_regularized_beta for small values and regularized_beta for bigger ones.
- .exact_cdf(k, n, pr) ⇒ Object
- .p_value(prob, n, pr) ⇒ Object
- .pdf(k, n, pr) ⇒ Object (also: exact_pdf)
Class Method Details
.cdf(k, n, pr) ⇒ Object
TODO: Use exact_regularized_beta for small values and regularized_beta for bigger ones.
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# File 'lib/distribution/binomial/ruby.rb', line 11 def cdf(k, n, pr) # (0..x.floor).inject(0) {|ac,i| ac+pdf(i,n,pr)} Math.regularized_beta(1 - pr, n - k, k + 1) end |
.exact_cdf(k, n, pr) ⇒ Object
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# File 'lib/distribution/binomial/ruby.rb', line 16 def exact_cdf(k, n, pr) out = (0..k).inject(0) { |ac, i| ac + pdf(i, n, pr) } out = 1 if out > 1.0 out end |
.p_value(prob, n, pr) ⇒ Object
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# File 'lib/distribution/binomial/ruby.rb', line 22 def p_value(prob, n, pr) ac = 0 (0..n).each do |i| ac += pdf(i, n, pr) return i if prob <= ac end end |
.pdf(k, n, pr) ⇒ Object Also known as: exact_pdf
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# File 'lib/distribution/binomial/ruby.rb', line 5 def pdf(k, n, pr) fail 'k>n' if k > n Math.binomial_coefficient(n, k) * (pr**k) * (1 - pr)**(n - k) end |