From 6b99afa5ae6b723a2c7678b07c4abcf7fc0b2129 Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Wed, 2 Sep 2015 15:34:03 +0200
Subject: [PATCH] Fix LSCG::solve with a sparse destination.

---
 Eigen/src/IterativeLinearSolvers/IterativeSolverBase.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Eigen/src/IterativeLinearSolvers/IterativeSolverBase.h b/Eigen/src/IterativeLinearSolvers/IterativeSolverBase.h
index a7cb30cb9..5f4bcea11 100644
--- a/Eigen/src/IterativeLinearSolvers/IterativeSolverBase.h
+++ b/Eigen/src/IterativeLinearSolvers/IterativeSolverBase.h
@@ -212,13 +212,17 @@ public:
     Index rhsCols = b.cols();
     Index size = b.rows();
     Eigen::Matrix<DestScalar,Dynamic,1> tb(size);
-    Eigen::Matrix<DestScalar,Dynamic,1> tx(size);
+    Eigen::Matrix<DestScalar,Dynamic,1> tx(cols());
+    // We do not directly fill dest because sparse expressions have to be free of aliasing issue.
+    // For non square least-square problems, b and dest might not have the same size whereas they might alias each-other.
+    SparseMatrix<DestScalar,DestOptions,DestIndex> tmp(cols(),rhsCols);
     for(Index k=0; k<rhsCols; ++k)
     {
       tb = b.col(k);
       tx = derived().solve(tb);
-      dest.col(k) = tx.sparseView(0);
+      tmp.col(k) = tx.sparseView(0);
     }
+    tmp.swap(dest);
   }
 
 protected: