e = exist('item')
exist('item'), where item is either a variable or a file, returns
0 if A is none of the following
1 if the variable A exists in the workspace
2 if either A or A.m is the name of a file on disk
3 if A is a MEX-file
4 if A is a compiled SIMULINK function
5 if A is a built-in MATLAB function
dir,help,lookfor,what,which,who
(c) Copyright 1994 by The MathWorks, Inc.