   
   n is the total number of values.
 
-  Example
+  Example:
 
       let x = [1, 2, 3.5, 3.7, 8, 12]
       let y = [0.5, 1, 2.1, 3.4, 3.4, 4]

  
  n is the population size.

  Example

      Sigma.standardDeviationPopulation([1, 12, 19.5, -5, 3, 8]) // 8.67419544780187



  n is the sample size.

  Example:

      Sigma.standardDeviationSample([1, 12, 19.5, -5, 3, 8]) // 8.674195447801869

