FUNCTION Add new function.
New functions may be added to MATLAB's vocabulary if they
are expressed in terms of other existing functions. The
commands and functions that comprise the new function must
be put in a file whose name defines the name of the new
function, with a filename extension of '.m'. At the top of
the file must be a line that contains the syntax definition
for the new function. For example, the existence of a file
on disk called STAT.M with: