AMSTDDEV()

  Short:
  ------
  AMSTDDEV() Standard Deviation on a given element of
  multi-dim array

  Returns:
  --------
  <nVariance> => average of array element

  Syntax:
  -------
  AMSTDDEV(aMult,nElem,[bCondition])

  Description:
  ------------
  Returns Standard Deviation of array <aMult> element
  <nElem>.  [bCondition] is an optional codeblock used to select a
  subset of the array. This could be used to filter out 0's or
  non-numeric elements.

  The block must accept a subarray as a parameter, and
  return true or false <expL> to determine if this element is
  part of the desired subset. Please note that the codeblock
  accepts the whole subarray, not  just subarray element <nElem>

  Examples:
  ---------
   ?"Total file size here is "
   ??AMSUM(DIRECTORY(),2)

   ?"Total .EXE file size here is "
   ??AMSUM(DIRECTORY(),2,{|e|".EXE"$e[1]}  )

   ?"Standard Deviation:"
   ??AMSTDDEV(DIRECTORY(),2,{|e|".EXE"$e[1]}  )

  Notes:
  -------
  Coded by Matthew Maier.

  Presumes all sub-arrays are of equal length

  Source:
  -------
  S_AMSTAT.PRG