From e43934d60f20d3f3884493d542bdcb0cb330c39a Mon Sep 17 00:00:00 2001
From: Jitse Niesen <jitse@maths.leeds.ac.uk>
Date: Fri, 26 Jul 2013 13:51:10 +0100
Subject: [PATCH] MatrixFunctions: Clean up StemFunction.h

---
 .../src/MatrixFunctions/MatrixFunction.h      |   8 +-
 .../Eigen/src/MatrixFunctions/StemFunction.h  | 170 ++++++++++--------
 unsupported/test/matrix_function.cpp          |   2 +-
 3 files changed, 96 insertions(+), 84 deletions(-)

diff --git a/unsupported/Eigen/src/MatrixFunctions/MatrixFunction.h b/unsupported/Eigen/src/MatrixFunctions/MatrixFunction.h
index 12e28793d..8a6b84c09 100644
--- a/unsupported/Eigen/src/MatrixFunctions/MatrixFunction.h
+++ b/unsupported/Eigen/src/MatrixFunctions/MatrixFunction.h
@@ -547,7 +547,7 @@ const MatrixFunctionReturnValue<Derived> MatrixBase<Derived>::sin() const
 {
   eigen_assert(rows() == cols());
   typedef typename internal::stem_function<Scalar>::ComplexScalar ComplexScalar;
-  return MatrixFunctionReturnValue<Derived>(derived(), StdStemFunctions<ComplexScalar>::sin);
+  return MatrixFunctionReturnValue<Derived>(derived(), internal::stem_function_sin<ComplexScalar>);
 }
 
 template <typename Derived>
@@ -555,7 +555,7 @@ const MatrixFunctionReturnValue<Derived> MatrixBase<Derived>::cos() const
 {
   eigen_assert(rows() == cols());
   typedef typename internal::stem_function<Scalar>::ComplexScalar ComplexScalar;
-  return MatrixFunctionReturnValue<Derived>(derived(), StdStemFunctions<ComplexScalar>::cos);
+  return MatrixFunctionReturnValue<Derived>(derived(), internal::stem_function_cos<ComplexScalar>);
 }
 
 template <typename Derived>
@@ -563,7 +563,7 @@ const MatrixFunctionReturnValue<Derived> MatrixBase<Derived>::sinh() const
 {
   eigen_assert(rows() == cols());
   typedef typename internal::stem_function<Scalar>::ComplexScalar ComplexScalar;
-  return MatrixFunctionReturnValue<Derived>(derived(), StdStemFunctions<ComplexScalar>::sinh);
+  return MatrixFunctionReturnValue<Derived>(derived(), internal::stem_function_sinh<ComplexScalar>);
 }
 
 template <typename Derived>
@@ -571,7 +571,7 @@ const MatrixFunctionReturnValue<Derived> MatrixBase<Derived>::cosh() const
 {
   eigen_assert(rows() == cols());
   typedef typename internal::stem_function<Scalar>::ComplexScalar ComplexScalar;
-  return MatrixFunctionReturnValue<Derived>(derived(), StdStemFunctions<ComplexScalar>::cosh);
+  return MatrixFunctionReturnValue<Derived>(derived(), internal::stem_function_cosh<ComplexScalar>);
 }
 
 } // end namespace Eigen
diff --git a/unsupported/Eigen/src/MatrixFunctions/StemFunction.h b/unsupported/Eigen/src/MatrixFunctions/StemFunction.h
index 0a815d834..cd45fe5b4 100644
--- a/unsupported/Eigen/src/MatrixFunctions/StemFunction.h
+++ b/unsupported/Eigen/src/MatrixFunctions/StemFunction.h
@@ -12,93 +12,105 @@
 
 namespace Eigen { 
 
-/** \ingroup MatrixFunctions_Module 
-  * \brief Stem functions corresponding to standard mathematical functions.
-  */
+namespace internal {
+
+/** \brief The exponential function (and its derivatives). */
 template <typename Scalar>
-class StdStemFunctions : internal::noncopyable
+Scalar stem_function_exp(Scalar x, int)
 {
-  public:
+  using std::exp;
+  return exp(x);
+}
 
-    /** \brief The exponential function (and its derivatives). */
-    static Scalar exp(Scalar x, int)
-    {
-      return std::exp(x);
-    }
+/** \brief Cosine (and its derivatives). */
+template <typename Scalar>
+Scalar stem_function_cos(Scalar x, int n)
+{
+  using std::cos;
+  using std::sin;
+  Scalar res;
 
-    /** \brief Cosine (and its derivatives). */
-    static Scalar cos(Scalar x, int n)
-    {
-      Scalar res;
-      switch (n % 4) {
-      case 0: 
-	res = std::cos(x);
-	break;
-      case 1:
-	res = -std::sin(x);
-	break;
-      case 2:
-	res = -std::cos(x);
-	break;
-      case 3:
-	res = std::sin(x);
-	break;
-      }
-      return res;
-    }
+  switch (n % 4) {
+  case 0: 
+    res = std::cos(x);
+    break;
+  case 1:
+    res = -std::sin(x);
+    break;
+  case 2:
+    res = -std::cos(x);
+    break;
+  case 3:
+    res = std::sin(x);
+    break;
+  }
+  return res;
+}
 
-    /** \brief Sine (and its derivatives). */
-    static Scalar sin(Scalar x, int n)
-    {
-      Scalar res;
-      switch (n % 4) {
-      case 0:
-	res = std::sin(x);
-	break;
-      case 1:
-	res = std::cos(x);
-	break;
-      case 2:
-	res = -std::sin(x);
-	break;
-      case 3:
-	res = -std::cos(x);
-	break;
-      }
-      return res;
-    }
+/** \brief Sine (and its derivatives). */
+template <typename Scalar>
+Scalar stem_function_sin(Scalar x, int n)
+{
+  using std::cos;
+  using std::sin;
+  Scalar res;
 
-    /** \brief Hyperbolic cosine (and its derivatives). */
-    static Scalar cosh(Scalar x, int n)
-    {
-      Scalar res;
-      switch (n % 2) {
-      case 0:
-	res = std::cosh(x);
-	break;
-      case 1:
-	res = std::sinh(x);
-	break;
-      }
-      return res;
-    }
+  switch (n % 4) {
+  case 0:
+    res = std::sin(x);
+    break;
+  case 1:
+    res = std::cos(x);
+    break;
+  case 2:
+    res = -std::sin(x);
+    break;
+  case 3:
+    res = -std::cos(x);
+    break;
+  }
+  return res;
+}
+
+/** \brief Hyperbolic cosine (and its derivatives). */
+template <typename Scalar>
+Scalar stem_function_cosh(Scalar x, int n)
+{
+  using std::cosh;
+  using std::sinh;
+  Scalar res;
+  
+  switch (n % 2) {
+  case 0:
+    res = std::cosh(x);
+    break;
+  case 1:
+    res = std::sinh(x);
+    break;
+  }
+  return res;
+}
 	
-    /** \brief Hyperbolic sine (and its derivatives). */
-    static Scalar sinh(Scalar x, int n)
-    {
-      Scalar res;
-      switch (n % 2) {
-      case 0:
-	res = std::sinh(x);
-	break;
-      case 1:
-	res = std::cosh(x);
-	break;
-      }
-      return res;
-    }
+/** \brief Hyperbolic sine (and its derivatives). */
+template <typename Scalar>
+Scalar stem_function_sinh(Scalar x, int n)
+{
+  using std::cosh;
+  using std::sinh;
+  Scalar res;
+  
+  switch (n % 2) {
+  case 0:
+    res = std::sinh(x);
+    break;
+  case 1:
+    res = std::cosh(x);
+    break;
+  }
+  return res;
+}
 
-}; // end of class StdStemFunctions
+} // end namespace internal
 
 } // end namespace Eigen
 
diff --git a/unsupported/test/matrix_function.cpp b/unsupported/test/matrix_function.cpp
index 3c76cfb65..487d5a9b8 100644
--- a/unsupported/test/matrix_function.cpp
+++ b/unsupported/test/matrix_function.cpp
@@ -102,7 +102,7 @@ void testMatrixExponential(const MatrixType& A)
   typedef typename NumTraits<Scalar>::Real RealScalar;
   typedef std::complex<RealScalar> ComplexScalar;
 
-  VERIFY_IS_APPROX(A.exp(), A.matrixFunction(StdStemFunctions<ComplexScalar>::exp));
+  VERIFY_IS_APPROX(A.exp(), A.matrixFunction(internal::stem_function_exp<ComplexScalar>));
 }
 
 template<typename MatrixType>