--- C:/InkscapeBZR/src/live_effects/lpe-powerstroke.cpp_bzr	Sun Jul  5 19:06:52 2015
+++ C:/InkscapeBZR/src/live_effects/lpe-powerstroke.cpp	Tue Jul 14 10:58:10 2015
@@ -566,7 +566,11 @@ LPEPowerStroke::doEffect_path (Geom::PathVector co
     // for now, only regard first subpath and ignore the rest
     Geom::Piecewise<Geom::D2<Geom::SBasis> > pwd2_in = path_in[0].toPwSb();
 
+    std::cout << "doEffect pwd2_in    = " << pwd2_in[0] << std::endl;
     Piecewise<D2<SBasis> > der = derivative(pwd2_in);
+    std::cout << "doEffect derivative = " << der[0] << std::endl;
+    std::cout << "doEffect at0()      = " << der[0].at0() << std::endl;
+    std::cout << "doEffect at1()      = " << der[0].at1() << std::endl;
     Piecewise<D2<SBasis> > n = rot90(unitVector(der));
     offset_points.set_pwd2(pwd2_in, n);