%EXIST  Check if variables or functions are defined.
%   EXIST('A') returns:
%     0 if A does not exist
%     1 if A is a variable in the workspace
%     2 if A is an M-file on MATLAB's search path or a file of unknown type 
%     3 if A is a MEX-file on MATLAB's search path
%     4 if A is a MDL-file on MATLAB's search path
%     5 if A is a built-in MATLAB function
%     6 if A is a P-file on MATLAB's search path
%     7 if A is a directory
%
%   EXIST('A') or EXIST('A.EXT') returns 2 if a file named 'A' or 'A.EXT'
%   is on MATLAB's search path and the extension isn't a P or MEX 
%   function extension.
%
%   EXIST('A','var') checks only for variables.
%   EXIST('A','builtin') checks only for built-in functions.
%   EXIST('A','file') checks for files or directories on MATLAB's search path.
%   EXIST('A','dir') checks only for directories.
%
%   EXIST returns 0 if the specified instance isn't found.
%
%   See also DIR, WHAT, ISEMPTY.

%   Copyright (c) 1984-98 by The MathWorks, Inc.
%   $Revision: 5.15 $  $Date: 1997/11/21 23:37:18 $
%   Built-in function.
