Improve treatment of constructor arguments.

+mafe/Node2D.m

@@ -8,14 +8,14 @@ classdef Node2D < mafe.Node
     methods
         %% constructor
         function obj = Node2D(ref_coords)
-            if nargin >= 1
-                obj.ref = ref_coords;
-            end
+          if exist('ref_coords','var')
+            obj.ref = ref_coords;
+          end
         end
         %% print nodal data
         function str = print(self)
-            str = sprintf('[% 7.3f,% 7.3f]', self.ref(1), self.ref(2));
-            str = strcat( str, print@mafe.Node(self) );
+          str = sprintf('[% 7.3f,% 7.3f]', self.ref(1), self.ref(2));
+          str = strcat( str, print@mafe.Node(self) );
         end
     end