WHICH WHICH Get Information on Function

Usage

Returns information on a function (if defined).  The usage is

   which(fname)

where fname is a string argument that contains the name of the 
function.  For functions and scripts defined
via .m files, the which command returns the location of the source
file:

   y = which(fname)

will return the filename for the .m file corresponding to the given
function, and an empty string otherwise.
