# Module: Distribution::Binomial::Ruby_

Defined in:
lib/distribution/binomial/ruby.rb

## Class Method Details

### .cdf(k, n, pr) ⇒ Object

TODO: Use exact_regularized_beta for small values and regularized_beta for bigger ones.

 ``` 14 15 16 17``` ```# File 'lib/distribution/binomial/ruby.rb', line 14 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

 ``` 19 20 21 22 23``` ```# File 'lib/distribution/binomial/ruby.rb', line 19 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```

### .pdf(k, n, pr) ⇒ ObjectAlso known as: exact_pdf

 ``` 5 6 7 8``` ```# 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```

### .quantile(prob, n, pr) ⇒ ObjectAlso known as: p_value

 ``` 25 26 27 28 29 30 31``` ```# File 'lib/distribution/binomial/ruby.rb', line 25 def quantile(prob, n, pr) ac = 0 (0..n).each do |i| ac += pdf(i, n, pr) return i if prob <= ac end end```