Minor patch to the Matlab interface

resources/MatlabInterface/@JEInterface/setVerbose.m

@@ -2,12 +2,15 @@ function int=setVerbose(int, bOn, varargin)
 % Activate debug output for the MatlabProblem.
 %      setVerbose(JI, bOn [, dbgfile])
 % It is written to a file with given name or to matlabproblem-debug.log 
-% if none is given.
+% if none is given. To switch file names, first deactivate logging.
 %   JI: the interface instance
 %   bOn: 1 activates debug output, 0 deactivates it
 %   dbgfile: optional filename
 %
 
+if (nargin<=1)
+    error('Missing argument!');
+end
 if (nargin > 2)
     if ischar(varargin{1})
         fname=varargin{1};
@@ -17,7 +20,7 @@ if (nargin > 2)
         disp('Invalid third argument, expected char. Using default output file name');
     end
 else
-    fname=null;
+    fname='';
 end
         
 int.mp.setDebugOut( bOn==1, fname);