diff --git a/dune/tectonic/samplefunctional.hh b/dune/tectonic/samplefunctional.hh
index 04d097797fe891c7118fad427fd2742af8b9ee50..ea9dfceb1b82f988ddfaf5df9fccf11447cc5009 100644
--- a/dune/tectonic/samplefunctional.hh
+++ b/dune/tectonic/samplefunctional.hh
@@ -31,6 +31,7 @@ template <int dim> class SampleFunctional {
     return y * v + (*phi)(v); // <1/2 Av - b,v> + H(|v|)
   }
 
+  // returns false if the direction is tangential
   bool descentDirection(SmallVector const x, SmallVector &ret) const {
     // Check the squared norm rather than each component because
     // complementaryProjection() divides by it
@@ -91,7 +92,9 @@ template <int dim> class SampleFunctional {
   SmallMatrix const &A;
   SmallVector const &b;
   shared_ptr<NonlinearityType const> const phi;
-  int const ignore;
+  int const ignore; // Dimension that should be ignored; goes from 0
+                    // to dim-1; the special value dim means that no
+                    // dimension should be ignored
 
 private:
   // Gradient of the smooth part