class Array
Public Instance Methods
covariance()
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# File lib/array.rb, line 3 def covariance sx, sy, sp = 0.0, 0.0, 0.0 return sx if empty? target = first.respond_to?(:to_ary) ? self : self.class.new(size) { |i| [i + 1, at(i)] } target.each { |x, y| sx += x sy += y sp += x * y } (sp - sx * sy / size) / size end