DoubleFunctionSample: constructor inheritance removed

lib/Function.cpp

@@ -147,6 +147,16 @@ MAKE_SELF_SCALAR_OP(/)
 /******************************************************************************
  *                    DoubleFunctionSample implementation                     *
  ******************************************************************************/
+// constructors ////////////////////////////////////////////////////////////////
+DoubleFunctionSample::DoubleFunctionSample(void)
+: Sample<DoubleFunction>()
+{}
+
+DoubleFunctionSample::DoubleFunctionSample(const Index nSample)
+: Sample<DoubleFunction>(nSample)
+{}
+
+// function call ///////////////////////////////////////////////////////////////
 DSample DoubleFunctionSample::operator()(const DMatSample &arg) const
 {
     DSample result(size());

lib/Function.hpp

@@ -156,7 +156,10 @@ class DoubleFunctionSample: public Sample<DoubleFunction>
 {
 public:
     // constructors
-    using Sample<DoubleFunction>::Sample;
+    DoubleFunctionSample(void);
+    DoubleFunctionSample(const Index nSample);
+    EIGEN_EXPR_CTOR(DoubleFunctionSample, DoubleFunctionSample,
+                    Sample<DoubleFunction>, ArrayExpr)
     // destructor
     virtual ~DoubleFunctionSample(void) = default;
     // function call