From 3454b4e5f1eb1a68e15415eeca827a30cb3bb58e Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Fri, 18 Apr 2014 17:06:03 +0200
Subject: [PATCH] Fix calls to lazy products (lazy product does not like
 matrices with 0 length)

---
 Eigen/src/Core/products/GeneralMatrixMatrix.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Eigen/src/Core/products/GeneralMatrixMatrix.h b/Eigen/src/Core/products/GeneralMatrixMatrix.h
index b45797f09..6ad07eccb 100644
--- a/Eigen/src/Core/products/GeneralMatrixMatrix.h
+++ b/Eigen/src/Core/products/GeneralMatrixMatrix.h
@@ -390,7 +390,7 @@ class GeneralProduct<Lhs, Rhs, GemmProduct>
     template<typename Dest>
     inline void evalTo(Dest& dst) const
     {
-      if((m_rhs.rows()+dst.rows()+dst.cols())<20)
+      if((m_rhs.rows()+dst.rows()+dst.cols())<20 && m_rhs.rows()>0)
         dst.noalias() = m_lhs .lazyProduct( m_rhs );
       else
       {
@@ -402,7 +402,7 @@ class GeneralProduct<Lhs, Rhs, GemmProduct>
     template<typename Dest>
     inline void addTo(Dest& dst) const
     {
-      if((m_rhs.rows()+dst.rows()+dst.cols())<20)
+      if((m_rhs.rows()+dst.rows()+dst.cols())<20 && m_rhs.rows()>0)
         dst.noalias() += m_lhs .lazyProduct( m_rhs );
       else
         scaleAndAddTo(dst,Scalar(1));
@@ -411,7 +411,7 @@ class GeneralProduct<Lhs, Rhs, GemmProduct>
     template<typename Dest>
     inline void subTo(Dest& dst) const
     {
-      if((m_rhs.rows()+dst.rows()+dst.cols())<20)
+      if((m_rhs.rows()+dst.rows()+dst.cols())<20 && m_rhs.rows()>0)
         dst.noalias() -= m_lhs .lazyProduct( m_rhs );
       else
         scaleAndAddTo(dst,Scalar(-1));