Check the norm rather than each component

src/samplefunctional.hh

@@ -35,7 +35,9 @@ template <int dimension> class SampleFunctional {
   }
 
   void descentDirection(const SmallVector x, SmallVector &ret) const {
-    if (x == SmallVector(0.0)) {
+    // Check the squared norm rather than each component because
+    // negative_projection() divides by it
+    if (x.two_norm2() == 0.0) {
       // If there is a direction of descent, this is it
       SmallVector const d = smoothGradient(x);