diff --git a/Eigen/src/misc/Solve.h b/Eigen/src/misc/Solve.h
new file mode 100644
index 0000000..7f70d60
--- /dev/null
+++ b/Eigen/src/misc/Solve.h
@@ -0,0 +1,76 @@
+// This file is part of Eigen, a lightweight C++ template library
+// for linear algebra.
+//
+// Copyright (C) 2009 Benoit Jacob <jacob.benoit.1@gmail.com>
+//
+// This Source Code Form is subject to the terms of the Mozilla
+// Public License v. 2.0. If a copy of the MPL was not distributed
+// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#ifndef EIGEN_MISC_SOLVE_H
+#define EIGEN_MISC_SOLVE_H
+
+namespace Eigen { 
+
+namespace internal {
+
+/** \class solve_retval_base
+  *
+  */
+template<typename DecompositionType, typename Rhs>
+struct traits<solve_retval_base<DecompositionType, Rhs> >
+{
+  typedef typename DecompositionType::MatrixType MatrixType;
+  typedef Matrix<typename Rhs::Scalar,
+                 MatrixType::ColsAtCompileTime,
+                 Rhs::ColsAtCompileTime,
+                 Rhs::PlainObject::Options,
+                 MatrixType::MaxColsAtCompileTime,
+                 Rhs::MaxColsAtCompileTime> ReturnType;
+};
+
+template<typename _DecompositionType, typename Rhs> struct solve_retval_base
+ : public ReturnByValue<solve_retval_base<_DecompositionType, Rhs> >
+{
+  typedef typename remove_all<typename Rhs::Nested>::type RhsNestedCleaned;
+  typedef _DecompositionType DecompositionType;
+  typedef ReturnByValue<solve_retval_base> Base;
+  typedef typename Base::Index Index;
+
+  solve_retval_base(const DecompositionType& dec, const Rhs& rhs)
+    : m_dec(dec), m_rhs(rhs)
+  {}
+
+  inline Index rows() const { return m_dec.cols(); }
+  inline Index cols() const { return m_rhs.cols(); }
+  inline const DecompositionType& dec() const { return m_dec; }
+  inline const RhsNestedCleaned& rhs() const { return m_rhs; }
+
+  template<typename Dest> inline void evalTo(Dest& dst) const
+  {
+    static_cast<const solve_retval<DecompositionType,Rhs>*>(this)->evalTo(dst);
+  }
+
+  protected:
+    const DecompositionType& m_dec;
+    typename Rhs::Nested m_rhs;
+};
+
+} // end namespace internal
+
+#define EIGEN_MAKE_SOLVE_HELPERS(DecompositionType,Rhs) \
+  typedef typename DecompositionType::MatrixType MatrixType; \
+  typedef typename MatrixType::Scalar Scalar; \
+  typedef typename MatrixType::RealScalar RealScalar; \
+  typedef typename MatrixType::Index Index; \
+  typedef Eigen::internal::solve_retval_base<DecompositionType,Rhs> Base; \
+  using Base::dec; \
+  using Base::rhs; \
+  using Base::rows; \
+  using Base::cols; \
+  solve_retval(const DecompositionType& dec, const Rhs& rhs) \
+    : Base(dec, rhs) {}
+
+} // end namespace Eigen
+
+#endif // EIGEN_MISC_SOLVE_H