Only run debugging code if NDEBUG is unset

src/bisection-example-flexible.cc

@@ -72,7 +72,7 @@ class SampleFunctional {
     }
     Dune::dverb << "Interval now [" << l << "," << r << "]" << std::endl;
 
-    // Debugging
+#ifndef NDEBUG
     {
       SmallVector tmpl = x;
       tmpl.axpy(l, descDir);
@@ -81,6 +81,7 @@ class SampleFunctional {
       assert(directionalDerivative(tmpl, descDir) < 0);
       assert(directionalDerivative(tmpr, descDir) > 0);
     }
+#endif
 
     double m = l / 2 + r / 2;
     SmallVector middle = SmallVector(0.0);