[common/float_cmp] changes complex comparison mode to element-wise

refs #59 and also tests float_cmp for actual floats

dune/stuff/common/float_cmp_internal.hh

@@ -115,10 +115,8 @@ typename std::enable_if<std::is_arithmetic<T>::value, bool>::type cmp_gt(const T
 template <class T>
 bool cmp_gt(const std::complex<T>& xx, const std::complex<T>& yy)
 {
-  T x = std::abs(xx);
-  T y = std::abs(yy);
-  static_assert(std::is_arithmetic<T>::value, "");
-  return std::greater<double>()(x, y);
+  using namespace std;
+  return cmp_gt({real(xx), real(yy)}, {imag(xx), imag(yy)});
 }
 
 template <class XType, class YType>
@@ -147,7 +145,8 @@ typename std::enable_if<std::is_arithmetic<T>::value, bool>::type cmp_lt(const T
 template <class T>
 bool cmp_lt(const std::complex<T>& xx, const std::complex<T>& yy)
 {
-  return std::less<T>()(std::abs(xx), std::abs(yy));
+  using namespace std;
+  return cmp_lt({real(xx), real(yy)}, {imag(xx), imag(yy)});
 }
 
 template <class XType, class YType>

dune/stuff/test/common_float_cmp.cc

@@ -436,7 +436,7 @@ struct FloatCmpVector : public FloatCmpBase
 }; // struct FloatCmpVector
 
 
-typedef testing::Types<double, std::complex<double>
+typedef testing::Types<double, std::complex<double>, float,
                        //                      , long double // <- this requires a patch in dune/common/float_cmp.cc
                        //                      (bc. of std::max and 1e-6)
                        > ScalarTypes;