Index: /trunk/psLib/src/math/psEllipse.c
===================================================================
--- /trunk/psLib/src/math/psEllipse.c	(revision 13075)
+++ /trunk/psLib/src/math/psEllipse.c	(revision 13076)
@@ -35,5 +35,6 @@
     pol.e0 = r*(PS_SQR(shape.sx) + PS_SQR(shape.sy));
     pol.e1 = r*(PS_SQR(shape.sx) - PS_SQR(shape.sy));
-    pol.e2 = r*(2.0*PS_SQR(shape.sx)*PS_SQR(shape.sy)*shape.sxy);
+    // XXX I do not understand this negative sign
+    pol.e2 = -r*(2.0*PS_SQR(shape.sx)*PS_SQR(shape.sy)*shape.sxy);
 
     assert (isfinite(pol.e0));