Average (J)
From LiteratePrograms
We want to define a function, named "avr", to find the average of a vector.
<<average.ijs>>= avr=:definition
To get the average we need to sum the elements of the vector, and divide it by the number of elements.
<<definition>>= sum%#
We get the sum by inserting the verb "+" between each pair of elements with the adverb "/"
<<sum>>= +/