function r=edit(fn1, fn2, fn3)
%EDIT Call the selected editor to edit the file.
%       
%       EDIT [FNAME] [FNAME] [FNAME]  
%
%       If the extension is not specified, .m will be
%       add to the filename.
%       EDIT accept until 3 file names but this depends
%       on the capability of the selected editor.
%       The default Editor is emacs.
%       You can use another editor setting the enviromental
%       variable MATLAB_EDITOR in your .cshrc
%       
%	Return 0 is if the command was correctly executed.
%	Returns a nonzero value in s to indicate failure
%	of the command.
%
%       See also KEDIT, SETENV (Unix command).
%
%       Claudio 16 August 1994
%

%
% Copyright (c) 1995 by Claudio Rivetti and Mark Young
% claudio@alice.uoregon.edu,    mark@alice.uoregon.edu
%

Editor = getenv('MATLAB_EDITOR');
sp=' ';

% Set the default editor in case MATLAB_EDITOR is not defined.
if isempty(Editor)
  Editor = 'emacs';
end

if nargin > 3
  error('Too many input arguments.');
end

if nargin > 0;
  if isempty(find(fn1 == '.'))
    fn1=[fn1, '.m'];
  end
else
  fn1=[];
end

if nargin > 1
  if isempty(find(fn2 == '.'))
    fn2=[fn2, '.m'];
  end
else
  fn2=[];
end

if nargin > 2
  if isempty(find(fn3 == '.'))
    fn3=[fn3, '.m'];
  end
else
  fn3=[];
end

filenames = [fn1,sp,fn2,sp,fn3];  

command=[Editor, sp, filenames, sp, '&'];
rr=unix(command);

if nargout==1
  r=rr
end

return