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 15 def exact_cdf(k,n,pr) out=(0..k).inject(0) {|ac,i| ac+pdf(i,n,pr)} out=1 if out>1.0 return out end |
.p_value(prob, n, pr) ⇒ Object
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# File 'lib/distribution/binomial/ruby.rb', line 20 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) raise "k>n" if k>n Math.binomial_coefficient(n,k)*(pr**k)*(1-pr)**(n-k) end |