 ## Calculating Standard Deviation – the function

Posted by: | December 20, 2016 Comments Off on Calculating Standard Deviation – the function |

Last time I showed how to calculate the standard deviation of a set of numbers and said the code could easily be turned into a function
``` function Measure-StandardDeviation { [CmdletBinding()] param ( [double[]]\$numbers ) \$mean = \$numbers | Measure-Object -Average | select -ExpandProperty Average \$sqdiffs = \$numbers | foreach {[math]::Pow((\$psitem - \$mean), 2)} ```
``` \$sigma = [math]::Sqrt( (\$sqdiffs | Measure-Object -Average | select -ExpandProperty Average) ) [math]::Round(\$sigma, 3) } ```

I’ve called the function Measure-StandardDeviation based on Measure-Object producing the mean.

The parameter is set to accept an array of doubles – floating point numbers – integers will be automatically converted to doubles.

To use the function
``` \$numbers = 1..10 Measure-StandardDeviation -numbers \$numbers ```

or create the input array directly
``` Measure-StandardDeviation -numbers (1..10) ```

under: PowerShell Basics