%PERSISTENT Define persistent variable.
%   PERSISTENT X Y Z defines X, Y, and Z as persistent in scope so that X,
%   Y and Z maintain their values from one call to the next.  PERSISTENT
%   can only be used within a function.  
%
%   Persistent variables are cleared when the M-file is cleared from
%   memory or when the M-file is changed.  To keep an M-file in memory
%   until MATLAB quits, use MLOCK.
%
%   If the persistent variable does not exist the first time you issue
%   the PERSISTENT statement, it will be initialized to the empty matrix.
%   Also it is an error to declare a variable persistent if a variable
%   with the same name exists in the current workspace.
%
%   Stylistically, persistent variables often have long names with all
%   capital letters, but this is not required.
%
%   See also GLOBAL, CLEAR, MLOCK, MUNLOCK, MISLOCKED.

%   Copyright (c) 1984-98 by The MathWorks, Inc.
%   $Revision: 1.3 $  $Date: 1998/06/26 19:05:10 $
%   Built-in function.
