Squashed 'third_party/eigen/' changes from 61d72f6..cf794d3


Change-Id: I9b814151b01f49af6337a8605d0c42a3a1ed4c72
git-subtree-dir: third_party/eigen
git-subtree-split: cf794d3b741a6278df169e58461f8529f43bce5d
diff --git a/unsupported/Eigen/src/MatrixFunctions/MatrixLogarithm.h b/unsupported/Eigen/src/MatrixFunctions/MatrixLogarithm.h
index c744fc0..cf5fffa 100644
--- a/unsupported/Eigen/src/MatrixFunctions/MatrixLogarithm.h
+++ b/unsupported/Eigen/src/MatrixFunctions/MatrixLogarithm.h
@@ -1,7 +1,7 @@
 // This file is part of Eigen, a lightweight C++ template library
 // for linear algebra.
 //
-// Copyright (C) 2011 Jitse Niesen <jitse@maths.leeds.ac.uk>
+// Copyright (C) 2011, 2013 Jitse Niesen <jitse@maths.leeds.ac.uk>
 // Copyright (C) 2011 Chen-Pang He <jdh8@ms63.hinet.net>
 //
 // This Source Code Form is subject to the terms of the Mozilla
@@ -11,91 +11,33 @@
 #ifndef EIGEN_MATRIX_LOGARITHM
 #define EIGEN_MATRIX_LOGARITHM
 
-#ifndef M_PI
-#define M_PI 3.141592653589793238462643383279503L
-#endif
-
 namespace Eigen { 
 
-/** \ingroup MatrixFunctions_Module
-  * \class MatrixLogarithmAtomic
-  * \brief Helper class for computing matrix logarithm of atomic matrices.
-  *
-  * \internal
-  * Here, an atomic matrix is a triangular matrix whose diagonal
-  * entries are close to each other.
-  *
-  * \sa class MatrixFunctionAtomic, MatrixBase::log()
-  */
-template <typename MatrixType>
-class MatrixLogarithmAtomic
+namespace internal { 
+
+template <typename Scalar>
+struct matrix_log_min_pade_degree 
 {
-public:
-
-  typedef typename MatrixType::Scalar Scalar;
-  // typedef typename MatrixType::Index Index;
-  typedef typename NumTraits<Scalar>::Real RealScalar;
-  // typedef typename internal::stem_function<Scalar>::type StemFunction;
-  // typedef Matrix<Scalar, MatrixType::RowsAtCompileTime, 1> VectorType;
-
-  /** \brief Constructor. */
-  MatrixLogarithmAtomic() { }
-
-  /** \brief Compute matrix logarithm of atomic matrix
-    * \param[in]  A  argument of matrix logarithm, should be upper triangular and atomic
-    * \returns  The logarithm of \p A.
-    */
-  MatrixType compute(const MatrixType& A);
-
-private:
-
-  void compute2x2(const MatrixType& A, MatrixType& result);
-  void computeBig(const MatrixType& A, MatrixType& result);
-  int getPadeDegree(float normTminusI);
-  int getPadeDegree(double normTminusI);
-  int getPadeDegree(long double normTminusI);
-  void computePade(MatrixType& result, const MatrixType& T, int degree);
-  void computePade3(MatrixType& result, const MatrixType& T);
-  void computePade4(MatrixType& result, const MatrixType& T);
-  void computePade5(MatrixType& result, const MatrixType& T);
-  void computePade6(MatrixType& result, const MatrixType& T);
-  void computePade7(MatrixType& result, const MatrixType& T);
-  void computePade8(MatrixType& result, const MatrixType& T);
-  void computePade9(MatrixType& result, const MatrixType& T);
-  void computePade10(MatrixType& result, const MatrixType& T);
-  void computePade11(MatrixType& result, const MatrixType& T);
-
-  static const int minPadeDegree = 3;
-  static const int maxPadeDegree = std::numeric_limits<RealScalar>::digits<= 24?  5:  // single precision
-                                   std::numeric_limits<RealScalar>::digits<= 53?  7:  // double precision
-                                   std::numeric_limits<RealScalar>::digits<= 64?  8:  // extended precision
-                                   std::numeric_limits<RealScalar>::digits<=106? 10:  // double-double
-                                                                                 11;  // quadruple precision
-
-  // Prevent copying
-  MatrixLogarithmAtomic(const MatrixLogarithmAtomic&);
-  MatrixLogarithmAtomic& operator=(const MatrixLogarithmAtomic&);
+  static const int value = 3;
 };
 
-/** \brief Compute logarithm of triangular matrix with clustered eigenvalues. */
-template <typename MatrixType>
-MatrixType MatrixLogarithmAtomic<MatrixType>::compute(const MatrixType& A)
+template <typename Scalar>
+struct matrix_log_max_pade_degree 
 {
-  using std::log;
-  MatrixType result(A.rows(), A.rows());
-  if (A.rows() == 1)
-    result(0,0) = log(A(0,0));
-  else if (A.rows() == 2)
-    compute2x2(A, result);
-  else
-    computeBig(A, result);
-  return result;
-}
+  typedef typename NumTraits<Scalar>::Real RealScalar;
+  static const int value = std::numeric_limits<RealScalar>::digits<= 24?  5:  // single precision
+                           std::numeric_limits<RealScalar>::digits<= 53?  7:  // double precision
+                           std::numeric_limits<RealScalar>::digits<= 64?  8:  // extended precision
+                           std::numeric_limits<RealScalar>::digits<=106? 10:  // double-double
+                                                                         11;  // quadruple precision
+};
 
 /** \brief Compute logarithm of 2x2 triangular matrix. */
 template <typename MatrixType>
-void MatrixLogarithmAtomic<MatrixType>::compute2x2(const MatrixType& A, MatrixType& result)
+void matrix_log_compute_2x2(const MatrixType& A, MatrixType& result)
 {
+  typedef typename MatrixType::Scalar Scalar;
+  typedef typename MatrixType::RealScalar RealScalar;
   using std::abs;
   using std::ceil;
   using std::imag;
@@ -108,59 +50,31 @@
   result(1,0) = Scalar(0);
   result(1,1) = logA11;
 
-  if (A(0,0) == A(1,1)) {
+  Scalar y = A(1,1) - A(0,0);
+  if (y==Scalar(0))
+  {
     result(0,1) = A(0,1) / A(0,0);
-  } else if ((abs(A(0,0)) < 0.5*abs(A(1,1))) || (abs(A(0,0)) > 2*abs(A(1,1)))) {
-    result(0,1) = A(0,1) * (logA11 - logA00) / (A(1,1) - A(0,0));
-  } else {
+  }
+  else if ((abs(A(0,0)) < RealScalar(0.5)*abs(A(1,1))) || (abs(A(0,0)) > 2*abs(A(1,1))))
+  {
+    result(0,1) = A(0,1) * (logA11 - logA00) / y;
+  }
+  else
+  {
     // computation in previous branch is inaccurate if A(1,1) \approx A(0,0)
-    int unwindingNumber = static_cast<int>(ceil((imag(logA11 - logA00) - M_PI) / (2*M_PI)));
-    Scalar y = A(1,1) - A(0,0), x = A(1,1) + A(0,0);
-    result(0,1) = A(0,1) * (Scalar(2) * numext::atanh2(y,x) + Scalar(0,2*M_PI*unwindingNumber)) / y;
+    int unwindingNumber = static_cast<int>(ceil((imag(logA11 - logA00) - RealScalar(EIGEN_PI)) / RealScalar(2*EIGEN_PI)));
+    result(0,1) = A(0,1) * (numext::log1p(y/A(0,0)) + Scalar(0,2*EIGEN_PI*unwindingNumber)) / y;
   }
 }
 
-/** \brief Compute logarithm of triangular matrices with size > 2. 
-  * \details This uses a inverse scale-and-square algorithm. */
-template <typename MatrixType>
-void MatrixLogarithmAtomic<MatrixType>::computeBig(const MatrixType& A, MatrixType& result)
-{
-  using std::pow;
-  int numberOfSquareRoots = 0;
-  int numberOfExtraSquareRoots = 0;
-  int degree;
-  MatrixType T = A, sqrtT;
-  const RealScalar maxNormForPade = maxPadeDegree<= 5? 5.3149729967117310e-1:                     // single precision
-                                    maxPadeDegree<= 7? 2.6429608311114350e-1:                     // double precision
-                                    maxPadeDegree<= 8? 2.32777776523703892094e-1L:                // extended precision
-                                    maxPadeDegree<=10? 1.05026503471351080481093652651105e-1L:    // double-double
-                                                       1.1880960220216759245467951592883642e-1L;  // quadruple precision
-
-  while (true) {
-    RealScalar normTminusI = (T - MatrixType::Identity(T.rows(), T.rows())).cwiseAbs().colwise().sum().maxCoeff();
-    if (normTminusI < maxNormForPade) {
-      degree = getPadeDegree(normTminusI);
-      int degree2 = getPadeDegree(normTminusI / RealScalar(2));
-      if ((degree - degree2 <= 1) || (numberOfExtraSquareRoots == 1)) 
-        break;
-      ++numberOfExtraSquareRoots;
-    }
-    MatrixSquareRootTriangular<MatrixType>(T).compute(sqrtT);
-    T = sqrtT.template triangularView<Upper>();
-    ++numberOfSquareRoots;
-  }
-
-  computePade(result, T, degree);
-  result *= pow(RealScalar(2), numberOfSquareRoots);
-}
-
 /* \brief Get suitable degree for Pade approximation. (specialized for RealScalar = float) */
-template <typename MatrixType>
-int MatrixLogarithmAtomic<MatrixType>::getPadeDegree(float normTminusI)
+inline int matrix_log_get_pade_degree(float normTminusI)
 {
   const float maxNormForPade[] = { 2.5111573934555054e-1 /* degree = 3 */ , 4.0535837411880493e-1,
             5.3149729967117310e-1 };
-  int degree = 3;
+  const int minPadeDegree = matrix_log_min_pade_degree<float>::value;
+  const int maxPadeDegree = matrix_log_max_pade_degree<float>::value;
+  int degree = minPadeDegree;
   for (; degree <= maxPadeDegree; ++degree) 
     if (normTminusI <= maxNormForPade[degree - minPadeDegree])
       break;
@@ -168,12 +82,13 @@
 }
 
 /* \brief Get suitable degree for Pade approximation. (specialized for RealScalar = double) */
-template <typename MatrixType>
-int MatrixLogarithmAtomic<MatrixType>::getPadeDegree(double normTminusI)
+inline int matrix_log_get_pade_degree(double normTminusI)
 {
   const double maxNormForPade[] = { 1.6206284795015624e-2 /* degree = 3 */ , 5.3873532631381171e-2,
             1.1352802267628681e-1, 1.8662860613541288e-1, 2.642960831111435e-1 };
-  int degree = 3;
+  const int minPadeDegree = matrix_log_min_pade_degree<double>::value;
+  const int maxPadeDegree = matrix_log_max_pade_degree<double>::value;
+  int degree = minPadeDegree;
   for (; degree <= maxPadeDegree; ++degree)
     if (normTminusI <= maxNormForPade[degree - minPadeDegree])
       break;
@@ -181,8 +96,7 @@
 }
 
 /* \brief Get suitable degree for Pade approximation. (specialized for RealScalar = long double) */
-template <typename MatrixType>
-int MatrixLogarithmAtomic<MatrixType>::getPadeDegree(long double normTminusI)
+inline int matrix_log_get_pade_degree(long double normTminusI)
 {
 #if   LDBL_MANT_DIG == 53         // double precision
   const long double maxNormForPade[] = { 1.6206284795015624e-2L /* degree = 3 */ , 5.3873532631381171e-2L,
@@ -204,7 +118,9 @@
             3.6688019729653446926585242192447447e-2L, 5.9290962294020186998954055264528393e-2L,
             8.6998436081634343903250580992127677e-2L, 1.1880960220216759245467951592883642e-1L };
 #endif
-  int degree = 3;
+  const int minPadeDegree = matrix_log_min_pade_degree<long double>::value;
+  const int maxPadeDegree = matrix_log_max_pade_degree<long double>::value;
+  int degree = minPadeDegree;
   for (; degree <= maxPadeDegree; ++degree)
     if (normTminusI <= maxNormForPade[degree - minPadeDegree])
       break;
@@ -213,197 +129,168 @@
 
 /* \brief Compute Pade approximation to matrix logarithm */
 template <typename MatrixType>
-void MatrixLogarithmAtomic<MatrixType>::computePade(MatrixType& result, const MatrixType& T, int degree)
+void matrix_log_compute_pade(MatrixType& result, const MatrixType& T, int degree)
 {
-  switch (degree) {
-    case 3:  computePade3(result, T);  break;
-    case 4:  computePade4(result, T);  break;
-    case 5:  computePade5(result, T);  break;
-    case 6:  computePade6(result, T);  break;
-    case 7:  computePade7(result, T);  break;
-    case 8:  computePade8(result, T);  break;
-    case 9:  computePade9(result, T);  break;
-    case 10: computePade10(result, T); break;
-    case 11: computePade11(result, T); break;
-    default: assert(false); // should never happen
+  typedef typename NumTraits<typename MatrixType::Scalar>::Real RealScalar;
+  const int minPadeDegree = 3;
+  const int maxPadeDegree = 11;
+  assert(degree >= minPadeDegree && degree <= maxPadeDegree);
+
+  const RealScalar nodes[][maxPadeDegree] = { 
+    { 0.1127016653792583114820734600217600L, 0.5000000000000000000000000000000000L,  // degree 3
+      0.8872983346207416885179265399782400L }, 
+    { 0.0694318442029737123880267555535953L, 0.3300094782075718675986671204483777L,  // degree 4
+      0.6699905217924281324013328795516223L, 0.9305681557970262876119732444464048L },
+    { 0.0469100770306680036011865608503035L, 0.2307653449471584544818427896498956L,  // degree 5
+      0.5000000000000000000000000000000000L, 0.7692346550528415455181572103501044L,
+      0.9530899229693319963988134391496965L },
+    { 0.0337652428984239860938492227530027L, 0.1693953067668677431693002024900473L,  // degree 6
+      0.3806904069584015456847491391596440L, 0.6193095930415984543152508608403560L,
+      0.8306046932331322568306997975099527L, 0.9662347571015760139061507772469973L },
+    { 0.0254460438286207377369051579760744L, 0.1292344072003027800680676133596058L,  // degree 7
+      0.2970774243113014165466967939615193L, 0.5000000000000000000000000000000000L,
+      0.7029225756886985834533032060384807L, 0.8707655927996972199319323866403942L,
+      0.9745539561713792622630948420239256L },
+    { 0.0198550717512318841582195657152635L, 0.1016667612931866302042230317620848L,  // degree 8
+      0.2372337950418355070911304754053768L, 0.4082826787521750975302619288199080L,
+      0.5917173212478249024697380711800920L, 0.7627662049581644929088695245946232L,
+      0.8983332387068133697957769682379152L, 0.9801449282487681158417804342847365L },
+    { 0.0159198802461869550822118985481636L, 0.0819844463366821028502851059651326L,  // degree 9
+      0.1933142836497048013456489803292629L, 0.3378732882980955354807309926783317L,
+      0.5000000000000000000000000000000000L, 0.6621267117019044645192690073216683L,
+      0.8066857163502951986543510196707371L, 0.9180155536633178971497148940348674L,
+      0.9840801197538130449177881014518364L },
+    { 0.0130467357414141399610179939577740L, 0.0674683166555077446339516557882535L,  // degree 10
+      0.1602952158504877968828363174425632L, 0.2833023029353764046003670284171079L,
+      0.4255628305091843945575869994351400L, 0.5744371694908156054424130005648600L,
+      0.7166976970646235953996329715828921L, 0.8397047841495122031171636825574368L,
+      0.9325316833444922553660483442117465L, 0.9869532642585858600389820060422260L },
+    { 0.0108856709269715035980309994385713L, 0.0564687001159523504624211153480364L,  // degree 11
+      0.1349239972129753379532918739844233L, 0.2404519353965940920371371652706952L,
+      0.3652284220238275138342340072995692L, 0.5000000000000000000000000000000000L,
+      0.6347715779761724861657659927004308L, 0.7595480646034059079628628347293048L,
+      0.8650760027870246620467081260155767L, 0.9435312998840476495375788846519636L,
+      0.9891143290730284964019690005614287L } };
+
+  const RealScalar weights[][maxPadeDegree] = { 
+    { 0.2777777777777777777777777777777778L, 0.4444444444444444444444444444444444L,  // degree 3
+      0.2777777777777777777777777777777778L },
+    { 0.1739274225687269286865319746109997L, 0.3260725774312730713134680253890003L,  // degree 4
+      0.3260725774312730713134680253890003L, 0.1739274225687269286865319746109997L },
+    { 0.1184634425280945437571320203599587L, 0.2393143352496832340206457574178191L,  // degree 5
+      0.2844444444444444444444444444444444L, 0.2393143352496832340206457574178191L,
+      0.1184634425280945437571320203599587L },
+    { 0.0856622461895851725201480710863665L, 0.1803807865240693037849167569188581L,  // degree 6
+      0.2339569672863455236949351719947755L, 0.2339569672863455236949351719947755L,
+      0.1803807865240693037849167569188581L, 0.0856622461895851725201480710863665L },
+    { 0.0647424830844348466353057163395410L, 0.1398526957446383339507338857118898L,  // degree 7
+      0.1909150252525594724751848877444876L, 0.2089795918367346938775510204081633L,
+      0.1909150252525594724751848877444876L, 0.1398526957446383339507338857118898L,
+      0.0647424830844348466353057163395410L },
+    { 0.0506142681451881295762656771549811L, 0.1111905172266872352721779972131204L,  // degree 8
+      0.1568533229389436436689811009933007L, 0.1813418916891809914825752246385978L,
+      0.1813418916891809914825752246385978L, 0.1568533229389436436689811009933007L,
+      0.1111905172266872352721779972131204L, 0.0506142681451881295762656771549811L },
+    { 0.0406371941807872059859460790552618L, 0.0903240803474287020292360156214564L,  // degree 9
+      0.1303053482014677311593714347093164L, 0.1561735385200014200343152032922218L,
+      0.1651196775006298815822625346434870L, 0.1561735385200014200343152032922218L,
+      0.1303053482014677311593714347093164L, 0.0903240803474287020292360156214564L,
+      0.0406371941807872059859460790552618L },
+    { 0.0333356721543440687967844049466659L, 0.0747256745752902965728881698288487L,  // degree 10
+      0.1095431812579910219977674671140816L, 0.1346333596549981775456134607847347L,
+      0.1477621123573764350869464973256692L, 0.1477621123573764350869464973256692L,
+      0.1346333596549981775456134607847347L, 0.1095431812579910219977674671140816L,
+      0.0747256745752902965728881698288487L, 0.0333356721543440687967844049466659L },
+    { 0.0278342835580868332413768602212743L, 0.0627901847324523123173471496119701L,  // degree 11
+      0.0931451054638671257130488207158280L, 0.1165968822959952399592618524215876L,
+      0.1314022722551233310903444349452546L, 0.1364625433889503153572417641681711L,
+      0.1314022722551233310903444349452546L, 0.1165968822959952399592618524215876L,
+      0.0931451054638671257130488207158280L, 0.0627901847324523123173471496119701L,
+      0.0278342835580868332413768602212743L } };
+
+  MatrixType TminusI = T - MatrixType::Identity(T.rows(), T.rows());
+  result.setZero(T.rows(), T.rows());
+  for (int k = 0; k < degree; ++k) {
+    RealScalar weight = weights[degree-minPadeDegree][k];
+    RealScalar node = nodes[degree-minPadeDegree][k];
+    result += weight * (MatrixType::Identity(T.rows(), T.rows()) + node * TminusI)
+                       .template triangularView<Upper>().solve(TminusI);
   }
 } 
 
+/** \brief Compute logarithm of triangular matrices with size > 2. 
+  * \details This uses a inverse scale-and-square algorithm. */
 template <typename MatrixType>
-void MatrixLogarithmAtomic<MatrixType>::computePade3(MatrixType& result, const MatrixType& T)
+void matrix_log_compute_big(const MatrixType& A, MatrixType& result)
 {
-  const int degree = 3;
-  const RealScalar nodes[]   = { 0.1127016653792583114820734600217600L, 0.5000000000000000000000000000000000L,
-            0.8872983346207416885179265399782400L };
-  const RealScalar weights[] = { 0.2777777777777777777777777777777778L, 0.4444444444444444444444444444444444L,
-            0.2777777777777777777777777777777778L };
-  eigen_assert(degree <= maxPadeDegree);
-  MatrixType TminusI = T - MatrixType::Identity(T.rows(), T.rows());
-  result.setZero(T.rows(), T.rows());
-  for (int k = 0; k < degree; ++k)
-    result += weights[k] * (MatrixType::Identity(T.rows(), T.rows()) + nodes[k] * TminusI)
-                           .template triangularView<Upper>().solve(TminusI);
+  typedef typename MatrixType::Scalar Scalar;
+  typedef typename NumTraits<Scalar>::Real RealScalar;
+  using std::pow;
+
+  int numberOfSquareRoots = 0;
+  int numberOfExtraSquareRoots = 0;
+  int degree;
+  MatrixType T = A, sqrtT;
+
+  int maxPadeDegree = matrix_log_max_pade_degree<Scalar>::value;
+  const RealScalar maxNormForPade = maxPadeDegree<= 5? 5.3149729967117310e-1L:                    // single precision
+                                    maxPadeDegree<= 7? 2.6429608311114350e-1L:                    // double precision
+                                    maxPadeDegree<= 8? 2.32777776523703892094e-1L:                // extended precision
+                                    maxPadeDegree<=10? 1.05026503471351080481093652651105e-1L:    // double-double
+                                                       1.1880960220216759245467951592883642e-1L;  // quadruple precision
+
+  while (true) {
+    RealScalar normTminusI = (T - MatrixType::Identity(T.rows(), T.rows())).cwiseAbs().colwise().sum().maxCoeff();
+    if (normTminusI < maxNormForPade) {
+      degree = matrix_log_get_pade_degree(normTminusI);
+      int degree2 = matrix_log_get_pade_degree(normTminusI / RealScalar(2));
+      if ((degree - degree2 <= 1) || (numberOfExtraSquareRoots == 1)) 
+        break;
+      ++numberOfExtraSquareRoots;
+    }
+    matrix_sqrt_triangular(T, sqrtT);
+    T = sqrtT.template triangularView<Upper>();
+    ++numberOfSquareRoots;
+  }
+
+  matrix_log_compute_pade(result, T, degree);
+  result *= pow(RealScalar(2), numberOfSquareRoots);
 }
 
+/** \ingroup MatrixFunctions_Module
+  * \class MatrixLogarithmAtomic
+  * \brief Helper class for computing matrix logarithm of atomic matrices.
+  *
+  * Here, an atomic matrix is a triangular matrix whose diagonal entries are close to each other.
+  *
+  * \sa class MatrixFunctionAtomic, MatrixBase::log()
+  */
 template <typename MatrixType>
-void MatrixLogarithmAtomic<MatrixType>::computePade4(MatrixType& result, const MatrixType& T)
+class MatrixLogarithmAtomic
 {
-  const int degree = 4;
-  const RealScalar nodes[]   = { 0.0694318442029737123880267555535953L, 0.3300094782075718675986671204483777L,
-            0.6699905217924281324013328795516223L, 0.9305681557970262876119732444464048L };
-  const RealScalar weights[] = { 0.1739274225687269286865319746109997L, 0.3260725774312730713134680253890003L,
-            0.3260725774312730713134680253890003L, 0.1739274225687269286865319746109997L };
-  eigen_assert(degree <= maxPadeDegree);
-  MatrixType TminusI = T - MatrixType::Identity(T.rows(), T.rows());
-  result.setZero(T.rows(), T.rows());
-  for (int k = 0; k < degree; ++k)
-    result += weights[k] * (MatrixType::Identity(T.rows(), T.rows()) + nodes[k] * TminusI)
-                           .template triangularView<Upper>().solve(TminusI);
-}
+public:
+  /** \brief Compute matrix logarithm of atomic matrix
+    * \param[in]  A  argument of matrix logarithm, should be upper triangular and atomic
+    * \returns  The logarithm of \p A.
+    */
+  MatrixType compute(const MatrixType& A);
+};
 
 template <typename MatrixType>
-void MatrixLogarithmAtomic<MatrixType>::computePade5(MatrixType& result, const MatrixType& T)
+MatrixType MatrixLogarithmAtomic<MatrixType>::compute(const MatrixType& A)
 {
-  const int degree = 5;
-  const RealScalar nodes[]   = { 0.0469100770306680036011865608503035L, 0.2307653449471584544818427896498956L,
-            0.5000000000000000000000000000000000L, 0.7692346550528415455181572103501044L,
-            0.9530899229693319963988134391496965L };
-  const RealScalar weights[] = { 0.1184634425280945437571320203599587L, 0.2393143352496832340206457574178191L,
-            0.2844444444444444444444444444444444L, 0.2393143352496832340206457574178191L,
-            0.1184634425280945437571320203599587L };
-  eigen_assert(degree <= maxPadeDegree);
-  MatrixType TminusI = T - MatrixType::Identity(T.rows(), T.rows());
-  result.setZero(T.rows(), T.rows());
-  for (int k = 0; k < degree; ++k)
-    result += weights[k] * (MatrixType::Identity(T.rows(), T.rows()) + nodes[k] * TminusI)
-                           .template triangularView<Upper>().solve(TminusI);
+  using std::log;
+  MatrixType result(A.rows(), A.rows());
+  if (A.rows() == 1)
+    result(0,0) = log(A(0,0));
+  else if (A.rows() == 2)
+    matrix_log_compute_2x2(A, result);
+  else
+    matrix_log_compute_big(A, result);
+  return result;
 }
 
-template <typename MatrixType>
-void MatrixLogarithmAtomic<MatrixType>::computePade6(MatrixType& result, const MatrixType& T)
-{
-  const int degree = 6;
-  const RealScalar nodes[]   = { 0.0337652428984239860938492227530027L, 0.1693953067668677431693002024900473L,
-            0.3806904069584015456847491391596440L, 0.6193095930415984543152508608403560L,
-            0.8306046932331322568306997975099527L, 0.9662347571015760139061507772469973L };
-  const RealScalar weights[] = { 0.0856622461895851725201480710863665L, 0.1803807865240693037849167569188581L,
-            0.2339569672863455236949351719947755L, 0.2339569672863455236949351719947755L,
-            0.1803807865240693037849167569188581L, 0.0856622461895851725201480710863665L };
-  eigen_assert(degree <= maxPadeDegree);
-  MatrixType TminusI = T - MatrixType::Identity(T.rows(), T.rows());
-  result.setZero(T.rows(), T.rows());
-  for (int k = 0; k < degree; ++k)
-    result += weights[k] * (MatrixType::Identity(T.rows(), T.rows()) + nodes[k] * TminusI)
-                           .template triangularView<Upper>().solve(TminusI);
-}
-
-template <typename MatrixType>
-void MatrixLogarithmAtomic<MatrixType>::computePade7(MatrixType& result, const MatrixType& T)
-{
-  const int degree = 7;
-  const RealScalar nodes[]   = { 0.0254460438286207377369051579760744L, 0.1292344072003027800680676133596058L,
-            0.2970774243113014165466967939615193L, 0.5000000000000000000000000000000000L,
-            0.7029225756886985834533032060384807L, 0.8707655927996972199319323866403942L,
-            0.9745539561713792622630948420239256L };
-  const RealScalar weights[] = { 0.0647424830844348466353057163395410L, 0.1398526957446383339507338857118898L,
-            0.1909150252525594724751848877444876L, 0.2089795918367346938775510204081633L,
-            0.1909150252525594724751848877444876L, 0.1398526957446383339507338857118898L,
-            0.0647424830844348466353057163395410L };
-  eigen_assert(degree <= maxPadeDegree);
-  MatrixType TminusI = T - MatrixType::Identity(T.rows(), T.rows());
-  result.setZero(T.rows(), T.rows());
-  for (int k = 0; k < degree; ++k)
-    result += weights[k] * (MatrixType::Identity(T.rows(), T.rows()) + nodes[k] * TminusI)
-                           .template triangularView<Upper>().solve(TminusI);
-}
-
-template <typename MatrixType>
-void MatrixLogarithmAtomic<MatrixType>::computePade8(MatrixType& result, const MatrixType& T)
-{
-  const int degree = 8;
-  const RealScalar nodes[]   = { 0.0198550717512318841582195657152635L, 0.1016667612931866302042230317620848L,
-            0.2372337950418355070911304754053768L, 0.4082826787521750975302619288199080L,
-            0.5917173212478249024697380711800920L, 0.7627662049581644929088695245946232L,
-            0.8983332387068133697957769682379152L, 0.9801449282487681158417804342847365L };
-  const RealScalar weights[] = { 0.0506142681451881295762656771549811L, 0.1111905172266872352721779972131204L,
-            0.1568533229389436436689811009933007L, 0.1813418916891809914825752246385978L,
-            0.1813418916891809914825752246385978L, 0.1568533229389436436689811009933007L,
-            0.1111905172266872352721779972131204L, 0.0506142681451881295762656771549811L };
-  eigen_assert(degree <= maxPadeDegree);
-  MatrixType TminusI = T - MatrixType::Identity(T.rows(), T.rows());
-  result.setZero(T.rows(), T.rows());
-  for (int k = 0; k < degree; ++k)
-    result += weights[k] * (MatrixType::Identity(T.rows(), T.rows()) + nodes[k] * TminusI)
-                           .template triangularView<Upper>().solve(TminusI);
-}
-
-template <typename MatrixType>
-void MatrixLogarithmAtomic<MatrixType>::computePade9(MatrixType& result, const MatrixType& T)
-{
-  const int degree = 9;
-  const RealScalar nodes[]   = { 0.0159198802461869550822118985481636L, 0.0819844463366821028502851059651326L,
-            0.1933142836497048013456489803292629L, 0.3378732882980955354807309926783317L,
-            0.5000000000000000000000000000000000L, 0.6621267117019044645192690073216683L,
-            0.8066857163502951986543510196707371L, 0.9180155536633178971497148940348674L,
-            0.9840801197538130449177881014518364L };
-  const RealScalar weights[] = { 0.0406371941807872059859460790552618L, 0.0903240803474287020292360156214564L,
-            0.1303053482014677311593714347093164L, 0.1561735385200014200343152032922218L,
-            0.1651196775006298815822625346434870L, 0.1561735385200014200343152032922218L,
-            0.1303053482014677311593714347093164L, 0.0903240803474287020292360156214564L,
-            0.0406371941807872059859460790552618L };
-  eigen_assert(degree <= maxPadeDegree);
-  MatrixType TminusI = T - MatrixType::Identity(T.rows(), T.rows());
-  result.setZero(T.rows(), T.rows());
-  for (int k = 0; k < degree; ++k)
-    result += weights[k] * (MatrixType::Identity(T.rows(), T.rows()) + nodes[k] * TminusI)
-                           .template triangularView<Upper>().solve(TminusI);
-}
-
-template <typename MatrixType>
-void MatrixLogarithmAtomic<MatrixType>::computePade10(MatrixType& result, const MatrixType& T)
-{
-  const int degree = 10;
-  const RealScalar nodes[]   = { 0.0130467357414141399610179939577740L, 0.0674683166555077446339516557882535L,
-            0.1602952158504877968828363174425632L, 0.2833023029353764046003670284171079L,
-            0.4255628305091843945575869994351400L, 0.5744371694908156054424130005648600L,
-            0.7166976970646235953996329715828921L, 0.8397047841495122031171636825574368L,
-            0.9325316833444922553660483442117465L, 0.9869532642585858600389820060422260L };
-  const RealScalar weights[] = { 0.0333356721543440687967844049466659L, 0.0747256745752902965728881698288487L,
-            0.1095431812579910219977674671140816L, 0.1346333596549981775456134607847347L,
-            0.1477621123573764350869464973256692L, 0.1477621123573764350869464973256692L,
-            0.1346333596549981775456134607847347L, 0.1095431812579910219977674671140816L,
-            0.0747256745752902965728881698288487L, 0.0333356721543440687967844049466659L };
-  eigen_assert(degree <= maxPadeDegree);
-  MatrixType TminusI = T - MatrixType::Identity(T.rows(), T.rows());
-  result.setZero(T.rows(), T.rows());
-  for (int k = 0; k < degree; ++k)
-    result += weights[k] * (MatrixType::Identity(T.rows(), T.rows()) + nodes[k] * TminusI)
-                           .template triangularView<Upper>().solve(TminusI);
-}
-
-template <typename MatrixType>
-void MatrixLogarithmAtomic<MatrixType>::computePade11(MatrixType& result, const MatrixType& T)
-{
-  const int degree = 11;
-  const RealScalar nodes[]   = { 0.0108856709269715035980309994385713L, 0.0564687001159523504624211153480364L,
-            0.1349239972129753379532918739844233L, 0.2404519353965940920371371652706952L,
-            0.3652284220238275138342340072995692L, 0.5000000000000000000000000000000000L,
-            0.6347715779761724861657659927004308L, 0.7595480646034059079628628347293048L,
-            0.8650760027870246620467081260155767L, 0.9435312998840476495375788846519636L,
-            0.9891143290730284964019690005614287L };
-  const RealScalar weights[] = { 0.0278342835580868332413768602212743L, 0.0627901847324523123173471496119701L,
-            0.0931451054638671257130488207158280L, 0.1165968822959952399592618524215876L,
-            0.1314022722551233310903444349452546L, 0.1364625433889503153572417641681711L,
-            0.1314022722551233310903444349452546L, 0.1165968822959952399592618524215876L,
-            0.0931451054638671257130488207158280L, 0.0627901847324523123173471496119701L,
-            0.0278342835580868332413768602212743L };
-  eigen_assert(degree <= maxPadeDegree);
-  MatrixType TminusI = T - MatrixType::Identity(T.rows(), T.rows());
-  result.setZero(T.rows(), T.rows());
-  for (int k = 0; k < degree; ++k)
-    result += weights[k] * (MatrixType::Identity(T.rows(), T.rows()) + nodes[k] * TminusI)
-                           .template triangularView<Upper>().solve(TminusI);
-}
+} // end of namespace internal
 
 /** \ingroup MatrixFunctions_Module
   *
@@ -421,45 +308,45 @@
 : public ReturnByValue<MatrixLogarithmReturnValue<Derived> >
 {
 public:
-
   typedef typename Derived::Scalar Scalar;
   typedef typename Derived::Index Index;
 
+protected:
+  typedef typename internal::ref_selector<Derived>::type DerivedNested;
+
+public:
+
   /** \brief Constructor.
     *
     * \param[in]  A  %Matrix (expression) forming the argument of the matrix logarithm.
     */
-  MatrixLogarithmReturnValue(const Derived& A) : m_A(A) { }
+  explicit MatrixLogarithmReturnValue(const Derived& A) : m_A(A) { }
   
   /** \brief Compute the matrix logarithm.
     *
-    * \param[out]  result  Logarithm of \p A, where \A is as specified in the constructor.
+    * \param[out]  result  Logarithm of \c A, where \c A is as specified in the constructor.
     */
   template <typename ResultType>
   inline void evalTo(ResultType& result) const
   {
-    typedef typename Derived::PlainObject PlainObject;
-    typedef internal::traits<PlainObject> Traits;
+    typedef typename internal::nested_eval<Derived, 10>::type DerivedEvalType;
+    typedef typename internal::remove_all<DerivedEvalType>::type DerivedEvalTypeClean;
+    typedef internal::traits<DerivedEvalTypeClean> Traits;
     static const int RowsAtCompileTime = Traits::RowsAtCompileTime;
     static const int ColsAtCompileTime = Traits::ColsAtCompileTime;
-    static const int Options = PlainObject::Options;
     typedef std::complex<typename NumTraits<Scalar>::Real> ComplexScalar;
-    typedef Matrix<ComplexScalar, Dynamic, Dynamic, Options, RowsAtCompileTime, ColsAtCompileTime> DynMatrixType;
-    typedef MatrixLogarithmAtomic<DynMatrixType> AtomicType;
+    typedef Matrix<ComplexScalar, Dynamic, Dynamic, 0, RowsAtCompileTime, ColsAtCompileTime> DynMatrixType;
+    typedef internal::MatrixLogarithmAtomic<DynMatrixType> AtomicType;
     AtomicType atomic;
     
-    const PlainObject Aevaluated = m_A.eval();
-    MatrixFunction<PlainObject, AtomicType> mf(Aevaluated, atomic);
-    mf.compute(result);
+    internal::matrix_function_compute<typename DerivedEvalTypeClean::PlainObject>::run(m_A, atomic, result);
   }
 
   Index rows() const { return m_A.rows(); }
   Index cols() const { return m_A.cols(); }
   
 private:
-  typename internal::nested<Derived>::type m_A;
-  
-  MatrixLogarithmReturnValue& operator=(const MatrixLogarithmReturnValue&);
+  const DerivedNested m_A;
 };
 
 namespace internal {