class StatiStica::StandardDeviation
Public Class Methods
new(sample)
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# File lib/stati_stica/standard_deviation.rb, line 5 def initialize(sample) raise ArgumentError if sample.empty? @sample = sample.map { |s| Float(s) } end
Public Instance Methods
value()
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# File lib/stati_stica/standard_deviation.rb, line 10 def value mean = StatiStica::Mean.new(@sample).value variance = @sample.inject(0) { |sum, element| sum + (element - mean) ** 2 } / (@sample.size - 1) Math.sqrt(variance) end