We have the correct coordinate system

dune/tectonic/globalnonlinearity.hh

@@ -53,7 +53,6 @@ class GlobalNonlinearity {
     for (size_t i = 0; i < u.size(); ++i) {
       Interval<double> D;
       auto const res = restriction(i);
-      // TODO: is the coordinate system the right one here?
       res->directionalSubDiff(u[i], v[i], D);
       subdifferential[0] += D[0];
       subdifferential[1] += D[1];

dune/tectonic/localnonlinearity.hh

@@ -43,7 +43,6 @@ template <int dimension> class LocalNonlinearity {
     }
     double const un = u.two_norm();
     double const ndotp = (u * v) / un;
-    // Our coordinate system is now such that v is a unit vector!
     if (ndotp > 0) {
       D[1] = ndotp * func_->rightDifferential(un);
       D[0] = ndotp * func_->leftDifferential(un);

src/TODO.org

 * check if v should be normalised by default
-* the subdifferentials for the nonlinearity are probably taken w.r.t a different coordinate system
 * use nested iteration to obtain better iteration to start with
 * fix up octave bindings (low-pri)