change order in normalGradient approximation

dune/curvedgeometry/localfunctiongeometry.hh

@@ -328,7 +328,7 @@ public:
     // construct a local finite-element type of the given order on the element
     using LFE = LagrangeLocalFiniteElement<EquidistantPointSet,mydimension,ctype,ctype>;
     using LocalBasisTraits = typename LFE::Traits::LocalBasisType::Traits;
-    LFE localFE{type(), order};
+    LFE localFE{type(), order > 1u ? order-1u : 1u};
 
     if (nCoefficients_.empty()) {
       // create local discrete function of normal vectors by interpolation of the geometry normal
@@ -338,7 +338,7 @@ public:
 
     // Interpolated normal vector evaluated at local coordinate
     thread_local std::vector<typename LocalBasisTraits::RangeType> nShapeValues;
-    localFE_.localBasis().evaluateFunction(local, nShapeValues);
+    localFE.localBasis().evaluateFunction(local, nShapeValues);
     GlobalCoordinate nh(0);
     for (std::size_t j = 0; j < nShapeValues.size(); ++j)
       nh.axpy(nShapeValues[j], nCoefficients_[j]);