* add Transpositions to PermutationMatrix conversion

* make PartialPivLu uses the  Transpositions class

Eigen/src/Core/PermutationMatrix.h

@@ -47,7 +47,6 @@
   *
   * \sa class DiagonalMatrix
   */
-template<int SizeAtCompileTime, int MaxSizeAtCompileTime = SizeAtCompileTime> class PermutationMatrix;
 template<typename PermutationType, typename MatrixType, int Side, bool Transposed=false> struct ei_permut_matrix_product_retval;
 
 template<int SizeAtCompileTime, int MaxSizeAtCompileTime>
@@ -78,8 +77,12 @@ class PermutationMatrix : public EigenBase<PermutationMatrix<SizeAtCompileTime,
     typedef Matrix<int, SizeAtCompileTime, 1, 0, MaxSizeAtCompileTime, 1> IndicesType;
 
     inline PermutationMatrix()
-    {
+    {}
-    }
+
+    /** Constructs an uninitialized permutation matrix of given size.
+      */
+    inline PermutationMatrix(int size) : m_indices(size)
+    {}
 
     /** Copy constructor. */
     template<int OtherSize, int OtherMaxSize>
@@ -103,6 +106,14 @@ class PermutationMatrix : public EigenBase<PermutationMatrix<SizeAtCompileTime,
     explicit inline PermutationMatrix(const MatrixBase<Other>& indices) : m_indices(indices)
     {}
 
+    /** Convert the Transpositions \a tr to a permutation matrix */
+    template<int OtherSize, int OtherMaxSize>
+    explicit PermutationMatrix(const Transpositions<OtherSize,OtherMaxSize>& tr)
+      : m_indices(tr.size())
+    {
+      *this = tr;
+    }
+
     /** Copies the other permutation into *this */
     template<int OtherSize, int OtherMaxSize>
     PermutationMatrix& operator=(const PermutationMatrix<OtherSize, OtherMaxSize>& other)
@@ -111,6 +122,15 @@ class PermutationMatrix : public EigenBase<PermutationMatrix<SizeAtCompileTime,
       return *this;
     }
 
+    /** Assignment from the Transpositions \a tr */
+    template<int OtherSize, int OtherMaxSize>
+    PermutationMatrix& operator=(const Transpositions<OtherSize,OtherMaxSize>& tr)
+    {
+      setIdentity(tr.size());
+      for(int k=size()-1; k>=0; --k)
+        applyTranspositionOnTheRight(k,tr.coeff(k));
+    }
+
     #ifndef EIGEN_PARSED_BY_DOXYGEN
     /** This is a special case of the templated operator=. Its purpose is to
       * prevent a default operator= from hiding the templated operator=.
@@ -122,11 +142,6 @@ class PermutationMatrix : public EigenBase<PermutationMatrix<SizeAtCompileTime,
     }
     #endif
 
-    /** Constructs an uninitialized permutation matrix of given size.
-      */
-    inline PermutationMatrix(int size) : m_indices(size)
-    {}
-
     /** \returns the number of rows */
     inline int rows() const { return m_indices.size(); }
 

Eigen/src/Core/Transpositions.h

@@ -52,7 +52,6 @@
   *
   * \sa class PermutationMatrix
   */
-template<int SizeAtCompileTime, int MaxSizeAtCompileTime = SizeAtCompileTime> class Transpositions;
 template<typename TranspositionType, typename MatrixType, int Side, bool Transposed=false> struct ei_transposition_matrix_product_retval;
 
 template<int SizeAtCompileTime, int MaxSizeAtCompileTime>
@@ -108,10 +107,18 @@ class Transpositions
     /** \returns the number of transpositions */
     inline Index size() const { return m_indices.size(); }
 
+    /** Direct access to the underlying index vector */
     inline const Index& coeff(Index i) const { return m_indices.coeff(i); }
+    /** Direct access to the underlying index vector */
     inline Index& coeffRef(Index i) { return m_indices.coeffRef(i); }
+    /** Direct access to the underlying index vector */
     inline const Index& operator()(Index i) const { return m_indices(i); }
+    /** Direct access to the underlying index vector */
     inline Index& operator()(Index i) { return m_indices(i); }
+    /** Direct access to the underlying index vector */
+    inline const Index& operator[](Index i) const { return m_indices(i); }
+    /** Direct access to the underlying index vector */
+    inline Index& operator[](Index i) { return m_indices(i); }
 
     /** const version of indices(). */
     const IndicesType& indices() const { return m_indices; }

Eigen/src/Core/util/ForwardDeclarations.h

@@ -77,6 +77,8 @@ template<typename _DiagonalVectorType> class DiagonalWrapper;
 template<typename _Scalar, int SizeAtCompileTime, int MaxSizeAtCompileTime=SizeAtCompileTime> class DiagonalMatrix;
 template<typename MatrixType, typename DiagonalType, int ProductOrder> class DiagonalProduct;
 template<typename MatrixType, int Index> class Diagonal;
+template<int SizeAtCompileTime, int MaxSizeAtCompileTime = SizeAtCompileTime> class PermutationMatrix;
+template<int SizeAtCompileTime, int MaxSizeAtCompileTime = SizeAtCompileTime> class Transpositions;
 
 template<int InnerStrideAtCompileTime, int OuterStrideAtCompileTime> class Stride;
 template<typename MatrixType, int MapOptions=Unaligned, typename StrideType = Stride<0,0> > class Map;

Eigen/src/LU/PartialPivLU.h

@@ -73,8 +73,8 @@ template<typename _MatrixType> class PartialPivLU
     typedef typename NumTraits<typename MatrixType::Scalar>::Real RealScalar;
     typedef typename ei_traits<MatrixType>::StorageKind StorageKind;
     typedef typename MatrixType::Index Index;
-    typedef typename ei_plain_col_type<MatrixType, Index>::type PermutationVectorType;
     typedef PermutationMatrix<RowsAtCompileTime, MaxRowsAtCompileTime> PermutationType;
+    typedef Transpositions<RowsAtCompileTime, MaxRowsAtCompileTime> TranspositionType;
 
 
     /**
@@ -186,7 +186,7 @@ template<typename _MatrixType> class PartialPivLU
   protected:
     MatrixType m_lu;
     PermutationType m_p;
-    PermutationVectorType m_rowsTranspositions;
+    TranspositionType m_rowsTranspositions;
     Index m_det_p;
     bool m_isInitialized;
 };
@@ -389,8 +389,8 @@ struct ei_partial_lu_impl
 
 /** \internal performs the LU decomposition with partial pivoting in-place.
   */
-template<typename MatrixType, typename IntVector>
+template<typename MatrixType, typename TranspositionType>
-void ei_partial_lu_inplace(MatrixType& lu, IntVector& row_transpositions, typename MatrixType::Index& nb_transpositions)
+void ei_partial_lu_inplace(MatrixType& lu, TranspositionType& row_transpositions, typename MatrixType::Index& nb_transpositions)
 {
   ei_assert(lu.cols() == row_transpositions.size());
   ei_assert((&row_transpositions.coeffRef(1)-&row_transpositions.coeffRef(0)) == 1);
@@ -414,9 +414,7 @@ PartialPivLU<MatrixType>& PartialPivLU<MatrixType>::compute(const MatrixType& ma
   ei_partial_lu_inplace(m_lu, m_rowsTranspositions, nb_transpositions);
   m_det_p = (nb_transpositions%2) ? -1 : 1;
 
-  m_p.setIdentity(size);
+  m_p = m_rowsTranspositions;
-  for(Index k = size-1; k >= 0; --k)
-    m_p.applyTranspositionOnTheRight(k, m_rowsTranspositions.coeff(k));
 
   m_isInitialized = true;
   return *this;