Fix adolcmaterialtest.cc

The test erroneously checked for a small *absolute* error, but the
numbers in this test are very large (around 1e8), so checking
for a small *relative* error is more appropriate.  This change
makes the test pass.

test/adolcmaterialtest.cc

 #include<config.h>
 
-#include <fstream>
 #include <random>
 
 #include <dune/fufem/assemblers/localassemblers/adolclocalenergy.hh>
@@ -11,7 +10,6 @@
 
 #include <dune/istl/bvector.hh>
 #include <dune/istl/bcrsmatrix.hh>
-#include <dune/istl/matrixindexset.hh>
 
 #include <dune/grid/uggrid.hh>
 
@@ -90,10 +88,15 @@ int main (int argc, char *argv[]) try
 
     for (size_t i=0; i < adolcGradient.size(); ++i) {
 
-        auto diff = adolcGradient[i] - paperGrad[i];
+        auto relativeError = (adolcGradient[i] - paperGrad[i]).two_norm()
+            / std::max(adolcGradient[i].two_norm(), paperGrad[i].two_norm());
 
-        if (diff.two_norm()>1e-5)
-            DUNE_THROW(Dune::Exception,"Wrong local derivative, error is "<<diff.two_norm());
+        if (relativeError > 1e-11)
+        {
+            std::cout << "adolc:\n" << adolcGradient[i] << std::endl;
+            std::cout << "closed-form:\n" << paperGrad[i] << std::endl;
+            DUNE_THROW(Dune::Exception,"Wrong local derivative, error is " << relativeError);
+        }
     }
 
     // Test hessian assembler
@@ -125,7 +128,6 @@ int main (int argc, char *argv[]) try
         auto adolcEndIt = adolcRow.end();
 
         auto paperIt = paperRow.begin();
-        auto paperEndIt = paperRow.end();
 
         for (; adolcIt != adolcEndIt; ++adolcIt, ++paperIt) {
 
@@ -133,18 +135,22 @@ int main (int argc, char *argv[]) try
                 DUNE_THROW(Dune::Exception,"Not the same sparsity pattern!"<<adolcIt.index()
                                 <<"!="<<paperIt.index());
 
-            auto diff = *adolcIt;
-            diff -= *paperIt;
+            auto relativeError = (*adolcIt - *paperIt).frobenius_norm()
+                / std::max(adolcIt->frobenius_norm(), paperIt->frobenius_norm());
 
-            if (diff.frobenius_norm() > 1e-4)
-                DUNE_THROW(Dune::Exception,"Wrong local hessian, error is "<<diff.frobenius_norm());
+            if (relativeError > 1e-11)
+            {
+                std::cout << "adolc:\n" << *adolcIt << std::endl;
+                std::cout << "closed-form:\n" << *paperIt << std::endl;
+                DUNE_THROW(Dune::Exception,"Wrong local hessian, error is " << relativeError);
+            }
         }
-        assert(paperIt==paperEndIt);
+        assert(paperIt==paperRow.end());
     }
 
     return 0;
 
-} catch (Exception e) {
+} catch (const Exception& e) {
     std::cout << e << std::endl;
     return 1;
 }