diff --git a/apps/shared/cartesian_function.cpp b/apps/shared/cartesian_function.cpp
index a87bf018c..a85bc818d 100644
--- a/apps/shared/cartesian_function.cpp
+++ b/apps/shared/cartesian_function.cpp
@@ -146,4 +146,18 @@ CartesianFunction::CartesianFunctionRecordDataBuffer * CartesianFunction::record
   return reinterpret_cast<CartesianFunctionRecordDataBuffer *>(const_cast<void *>(d.buffer));
 }
 
+template<typename T>
+T CartesianFunction::templatedApproximateAtAbscissa(T x, Poincare::Context * context) const {
+  if (isCircularlyDefined(context)) {
+    return NAN;
+  }
+  constexpr int bufferSize = CodePoint::MaxCodePointCharLength + 1;
+  char unknownX[bufferSize];
+  Poincare::SerializationHelper::CodePoint(unknownX, bufferSize, UCodePointUnknownX);
+  return PoincareHelpers::ApproximateWithValueForSymbol(expressionReduced(context), unknownX, x, context);
+}
+
+template float CartesianFunction::templatedApproximateAtAbscissa<float>(float, Poincare::Context *) const;
+template double CartesianFunction::templatedApproximateAtAbscissa<double>(double, Poincare::Context *) const;
+
 }
diff --git a/apps/shared/cartesian_function.h b/apps/shared/cartesian_function.h
index 9e91cf061..f9d769a40 100644
--- a/apps/shared/cartesian_function.h
+++ b/apps/shared/cartesian_function.h
@@ -17,6 +17,13 @@ public:
   CodePoint symbol() const override { return 'x'; }
   CodePoint unknownSymbol() const override { return UCodePointUnknownX; }
 
+  // Evaluation
+  float evaluateAtAbscissa(float x, Poincare::Context * context) const override {
+    return templatedApproximateAtAbscissa(x, context);
+  }
+  double evaluateAtAbscissa(double x, Poincare::Context * context) const override {
+    return templatedApproximateAtAbscissa(x, context);
+  }
   // Derivative
   bool displayDerivative() const;
   void setDisplayDerivative(bool display);
@@ -59,6 +66,7 @@ private:
   size_t metaDataSize() const override { return sizeof(CartesianFunctionRecordDataBuffer); }
   const ExpressionModel * model() const override { return &m_model; }
   CartesianFunctionRecordDataBuffer * recordData() const;
+  template<typename T> T templatedApproximateAtAbscissa(T x, Poincare::Context * context) const;
   Model m_model;
 };
 
diff --git a/apps/shared/function.cpp b/apps/shared/function.cpp
index 52f43894d..01f284303 100644
--- a/apps/shared/function.cpp
+++ b/apps/shared/function.cpp
@@ -1,6 +1,4 @@
 #include "function.h"
-#include "poincare_helpers.h"
-#include <poincare/serialization_helper.h>
 #include "poincare/src/parsing/parser.h"
 #include <ion/unicode/utf8_helper.h>
 #include <ion/unicode/utf8_decoder.h>
@@ -77,24 +75,10 @@ int Function::nameWithArgument(char * buffer, size_t bufferSize) {
   return result;
 }
 
-template<typename T>
-T Function::templatedApproximateAtAbscissa(T x, Poincare::Context * context) const {
-  if (isCircularlyDefined(context)) {
-    return NAN;
-  }
-  constexpr int bufferSize = CodePoint::MaxCodePointCharLength + 1;
-  char unknownX[bufferSize];
-  Poincare::SerializationHelper::CodePoint(unknownX, bufferSize, UCodePointUnknownX);
-  return PoincareHelpers::ApproximateWithValueForSymbol(expressionReduced(context), unknownX, x, context);
-}
-
 Function::FunctionRecordDataBuffer * Function::recordData() const {
   assert(!isNull());
   Ion::Storage::Record::Data d = value();
   return reinterpret_cast<FunctionRecordDataBuffer *>(const_cast<void *>(d.buffer));
 }
 
-template float Function::templatedApproximateAtAbscissa<float>(float, Poincare::Context*) const;
-template double Function::templatedApproximateAtAbscissa<double>(double, Poincare::Context*) const;
-
 }
diff --git a/apps/shared/function.h b/apps/shared/function.h
index fc07f615d..207a35796 100644
--- a/apps/shared/function.h
+++ b/apps/shared/function.h
@@ -36,12 +36,8 @@ public:
   int nameWithArgument(char * buffer, size_t bufferSize);
 
   // Evaluation
-  virtual float evaluateAtAbscissa(float x, Poincare::Context * context) const {
-    return templatedApproximateAtAbscissa(x, context);
-  }
-  virtual double evaluateAtAbscissa(double x, Poincare::Context * context) const {
-    return templatedApproximateAtAbscissa(x, context);
-  }
+  virtual float evaluateAtAbscissa(float x, Poincare::Context * context) const = 0;
+  virtual double evaluateAtAbscissa(double x, Poincare::Context * context) const = 0;
   virtual double sumBetweenBounds(double start, double end, Poincare::Context * context) const = 0;
 protected:
   /* FunctionRecordDataBuffer is the layout of the data buffer of Record
@@ -76,7 +72,6 @@ protected:
   };
 #pragma pack(pop)
 private:
-  template<typename T> T templatedApproximateAtAbscissa(T x, Poincare::Context * context) const;
   FunctionRecordDataBuffer * recordData() const;
 };