diff --git a/+mgen/MgGeoArea4LineEllipsoidalVoid.m b/+mgen/MgGeoArea4LineEllipsoidalVoid.m
index 5074d416e13016c8f7f3526a61a43d07845c6614..09c797a73a06d4c41828034e2ebcecac0d761299 100644
--- a/+mgen/MgGeoArea4LineEllipsoidalVoid.m
+++ b/+mgen/MgGeoArea4LineEllipsoidalVoid.m
@@ -59,11 +59,22 @@ classdef MgGeoArea4LineEllipsoidalVoid < mgen.MgGeoArea4Line
             %fig = figure(1); subplot('Position',[0.05 0.05 0.90 0.90]); axis equal; hold on;
 
             gnv = gridnodes;
-
+            for kk = 1:4
+                if self.geoLines(kk).getNumTargetGridNodes() - 1 ==0
+                    warning('increase the number of nodes in the %d line',kk)
+                    
+                end
+            end
             dim0     = self.geoLines(1).getNumTargetGridNodes() - 1;
+            
+            assert(dim0>0);
             dim1     = self.geoLines(2).getNumTargetGridNodes() - 1;
+            assert(dim1>0);
+           
             dim2     = self.geoLines(3).getNumTargetGridNodes() - 1;
+            assert(dim2>0);
             dim3     = self.geoLines(4).getNumTargetGridNodes() - 1;
+            assert(dim3>0); 
             dim      = self.nrings*(dim0 + dim1 + dim2 + dim3);
             segments = self.nrings - 1;
             run_id   = 1 + length(gridnodes);
@@ -95,18 +106,28 @@ classdef MgGeoArea4LineEllipsoidalVoid < mgen.MgGeoArea4Line
             % create grid nodes
             for mm = segments:-1:1 % loop over segments from outer to inner
 
-                % set function values
-                self.normFunction.vals(1) = segments;
-                if self.normFunction.vals(2) == 0
+                % set function values if the normFunction is not set by
+                % user
+                if  self.normFunction.vals == [0,0]
                     self.normFunction.vals(1) = segments;
+                    if self.normFunction.vals(2) == 0
+                        self.normFunction.vals(1) = segments;
+                    end
+                    if self.normFunction.vals(1) == 1
+                        self.normFunction.vals(2) = segments;
+                    end
                 end
-                if self.normFunction.vals(1) == 1
-                    self.normFunction.vals(2) = segments;
+                % some bugs occurs if user sets the type of normFunction.
+                if self.normFunction.vals(1)>self.normFunction.vals(2)
+                   self.normFunction.vals=sort(self.normFunction.vals)
                 end
-
+                
                 scale = self.normFunction.eval( mm/segments );
-
-                for gline = self.geoLines % loop over the four GeoLines
+                if isnan(scale) 
+                    warning('normFunction can not eval %d/%d',mm,segments)
+                end
+                
+		for gline = self.geoLines % loop over the four GeoLines
 
                     for ii = 1:gline.getNumTargetGridNodes - 1 % loop over GridNodes - 1
 
@@ -135,10 +156,12 @@ classdef MgGeoArea4LineEllipsoidalVoid < mgen.MgGeoArea4Line
                     end
                 end
             end
-
+	    % defensive programming: check if ringNodes is filled.
+            assert(~isempty(self.ringNodes))
+ 
             % make sure the ring nodes represent a closed line in terms of node connectivity
             self.ringNodes(end+1) = self.ringNodes(1);
-
+	
             % sort in existing nodes
             for gline = self.geoLines
                 for ii = 1:gline.getNumTargetGridNodes - 1
diff --git a/extra/circleGeom/MeshHole.m b/extra/circleGeom/MeshHole.m
new file mode 100644
index 0000000000000000000000000000000000000000..2a71e87495c8c92abbdee9f6d43087df39d07582
--- /dev/null
+++ b/extra/circleGeom/MeshHole.m
@@ -0,0 +1,33 @@
+%% Describe the goemetry of the problem for the mesh generator
+% helfpul parameters (problem specific)
+n = 10;% should be >1! % d: length measure; n = number of grid nodes per d
+% create all geo points
+
+gp1 = mgen.MgGeoPoint( [-1, -1] );
+gp2 = mgen.MgGeoPoint( [1, -1] );
+gp3 = mgen.MgGeoPoint( [1, 1] );
+gp4 = mgen.MgGeoPoint( [-1, 1] );
+gcenter = mgen.MgGeoPoint([0.,0.]);
+gl1  = mgen.MgGeoLine2Point( [gp1, gp2], n );
+gl2  = mgen.MgGeoLine2Point( [gp2, gp3], n );
+gl3  = mgen.MgGeoLine2Point( [gp3, gp4], n );
+gl4  = mgen.MgGeoLine2Point( [gp4, gp1], n );
+
+%number of ring => refine near the circle
+a= 0.5%
+b= 0.5%
+c=0; %ellipse rotation angle in rad
+normFunc = mgen.MgNormFunction( mgen.MgNormFunctionType.Quadratic);
+
+ga1  = mgen.MgGeoArea4LineEllipsoidalVoid([gl1,gl2,gl3,gl4],20,a,b,c,normFunc)
+
+% create geo object and generate the mesh
+geo = mgen.MgGeo( [gp1, gp2, gp3, gp4], ...
+                  [gl1, gl2, gl3, gl4], ...
+                  [ga1] );
+% print geo and mesh data info
+fprintf(geo.print());
+% plot mesh
+cla; clf;
+fig = figure(1); subplot('Position',[0.05 0.05 0.90 0.90]); axis equal; hold on;
+geo.plot();
\ No newline at end of file