From 93125e372df80f07bb7d74abdebb592425ddba7b Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Thu, 20 Feb 2014 15:26:15 +0100
Subject: Port LU module to evaluators (except image() and kernel())

---
 Eigen/src/LU/PartialPivLU.h | 85 +++++++++++++++++++++++++++++++++++++--------
 1 file changed, 70 insertions(+), 15 deletions(-)

(limited to 'Eigen/src/LU/PartialPivLU.h')

diff --git a/Eigen/src/LU/PartialPivLU.h b/Eigen/src/LU/PartialPivLU.h
index 1d389ecac..ac53f7ab5 100644
--- a/Eigen/src/LU/PartialPivLU.h
+++ b/Eigen/src/LU/PartialPivLU.h
@@ -13,6 +13,19 @@
 
 namespace Eigen { 
 
+namespace internal {
+template<typename _MatrixType> struct traits<PartialPivLU<_MatrixType> >
+ : traits<_MatrixType>
+{
+  typedef traits<_MatrixType> BaseTraits;
+  enum {
+    Flags = BaseTraits::Flags & RowMajorBit,
+    CoeffReadCost = Dynamic
+  };
+};
+
+} // end namespace internal
+
 /** \ingroup LU_Module
   *
   * \class PartialPivLU
@@ -62,6 +75,7 @@ template<typename _MatrixType> class PartialPivLU
     typedef typename MatrixType::Index Index;
     typedef PermutationMatrix<RowsAtCompileTime, MaxRowsAtCompileTime> PermutationType;
     typedef Transpositions<RowsAtCompileTime, MaxRowsAtCompileTime> TranspositionType;
+    typedef typename MatrixType::PlainObject PlainObject;
 
 
     /**
@@ -128,6 +142,15 @@ template<typename _MatrixType> class PartialPivLU
       *
       * \sa TriangularView::solve(), inverse(), computeInverse()
       */
+#ifdef EIGEN_TEST_EVALUATORS
+    template<typename Rhs>
+    inline const Solve<PartialPivLU, Rhs>
+    solve(const MatrixBase<Rhs>& b) const
+    {
+      eigen_assert(m_isInitialized && "PartialPivLU is not initialized.");
+      return Solve<PartialPivLU, Rhs>(*this, b.derived());
+    }
+#else
     template<typename Rhs>
     inline const internal::solve_retval<PartialPivLU, Rhs>
     solve(const MatrixBase<Rhs>& b) const
@@ -135,6 +158,7 @@ template<typename _MatrixType> class PartialPivLU
       eigen_assert(m_isInitialized && "PartialPivLU is not initialized.");
       return internal::solve_retval<PartialPivLU, Rhs>(*this, b.derived());
     }
+#endif
 
     /** \returns the inverse of the matrix of which *this is the LU decomposition.
       *
@@ -143,12 +167,20 @@ template<typename _MatrixType> class PartialPivLU
       *
       * \sa MatrixBase::inverse(), LU::inverse()
       */
+#ifdef EIGEN_TEST_EVALUATORS
+    inline const Inverse<PartialPivLU> inverse() const
+    {
+      eigen_assert(m_isInitialized && "PartialPivLU is not initialized.");
+      return Inverse<PartialPivLU>(*this);
+    }
+#else
     inline const internal::solve_retval<PartialPivLU,typename MatrixType::IdentityReturnType> inverse() const
     {
       eigen_assert(m_isInitialized && "PartialPivLU is not initialized.");
       return internal::solve_retval<PartialPivLU,typename MatrixType::IdentityReturnType>
                (*this, MatrixType::Identity(m_lu.rows(), m_lu.cols()));
     }
+#endif
 
     /** \returns the determinant of the matrix of which
       * *this is the LU decomposition. It has only linear complexity
@@ -169,6 +201,30 @@ template<typename _MatrixType> class PartialPivLU
 
     inline Index rows() const { return m_lu.rows(); }
     inline Index cols() const { return m_lu.cols(); }
+    
+    #ifndef EIGEN_PARSED_BY_DOXYGEN
+    template<typename RhsType, typename DstType>
+    EIGEN_DEVICE_FUNC
+    void _solve_impl(const RhsType &rhs, DstType &dst) const {
+     /* The decomposition PA = LU can be rewritten as A = P^{-1} L U.
+      * So we proceed as follows:
+      * Step 1: compute c = Pb.
+      * Step 2: replace c by the solution x to Lx = c.
+      * Step 3: replace c by the solution x to Ux = c.
+      */
+
+      eigen_assert(rhs.rows() == m_lu.rows());
+
+      // Step 1
+      dst = permutationP() * rhs;
+
+      // Step 2
+      m_lu.template triangularView<UnitLower>().solveInPlace(dst);
+
+      // Step 3
+      m_lu.template triangularView<Upper>().solveInPlace(dst); 
+    }
+    #endif
 
   protected:
     MatrixType m_lu;
@@ -434,6 +490,7 @@ MatrixType PartialPivLU<MatrixType>::reconstructedMatrix() const
 
 namespace internal {
 
+#ifndef EIGEN_TEST_EVALUATORS
 template<typename _MatrixType, typename Rhs>
 struct solve_retval<PartialPivLU<_MatrixType>, Rhs>
   : solve_retval_base<PartialPivLU<_MatrixType>, Rhs>
@@ -442,23 +499,21 @@ struct solve_retval<PartialPivLU<_MatrixType>, Rhs>
 
   template<typename Dest> void evalTo(Dest& dst) const
   {
-    /* The decomposition PA = LU can be rewritten as A = P^{-1} L U.
-    * So we proceed as follows:
-    * Step 1: compute c = Pb.
-    * Step 2: replace c by the solution x to Lx = c.
-    * Step 3: replace c by the solution x to Ux = c.
-    */
-
-    eigen_assert(rhs().rows() == dec().matrixLU().rows());
-
-    // Step 1
-    dst = dec().permutationP() * rhs();
+    dec()._solve_impl(rhs(), dst);
+  }
+};
+#endif
 
-    // Step 2
-    dec().matrixLU().template triangularView<UnitLower>().solveInPlace(dst);
+/***** Implementation of inverse() *****************************************************/
 
-    // Step 3
-    dec().matrixLU().template triangularView<Upper>().solveInPlace(dst);
+template<typename DstXprType, typename MatrixType, typename Scalar>
+struct Assignment<DstXprType, Inverse<PartialPivLU<MatrixType> >, internal::assign_op<Scalar>, Dense2Dense, Scalar>
+{
+  typedef PartialPivLU<MatrixType> LuType;
+  typedef Inverse<LuType> SrcXprType;
+  static void run(DstXprType &dst, const SrcXprType &src, const internal::assign_op<Scalar> &)
+  {    
+    dst = src.nestedExpression().solve(MatrixType::Identity(src.rows(), src.cols()));
   }
 };
 
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