averageDifference

The average for the pair of data names given by the strings. If the data names don't exist or the difference "

$s1 - $

s2" does not exist, an exception will be thrown.

Return

average for the pair of data names given by the "

$s1 - $

s2"

Parameters

s1

the name of data set number 1

s2

the name of data set number 2