Add bin and edit workflow

bin/gems/facets-3.1.0/lib/standard/facets/math/summed_sqdevs.rb

@@ -0,0 +1,14 @@
+require 'facets/math/sum'
+require 'facets/math/mean'
+
+module Math
+
+  # The sum of the squared deviations from the mean.
+  #
+  def self.summed_sqdevs(array)
+    return 0 if array.size < 2
+    m = mean(array)
+    sum(array.map{ |x| (x - m) ** 2 })
+  end
+
+end