From 97c9e3c74f9dd9f33f3f1699801aed0c7dfbafb4 Mon Sep 17 00:00:00 2001
From: Jitse Niesen <jitse@maths.leeds.ac.uk>
Date: Sat, 9 Mar 2013 16:58:05 +0000
Subject: [PATCH] Handle special case in atanh2(x,y) when y = 0. This fixes
 matrix_power unit test on clang.

---
 Eigen/src/Core/MathFunctions.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Eigen/src/Core/MathFunctions.h b/Eigen/src/Core/MathFunctions.h
index fab2d9a72..a2c55f255 100644
--- a/Eigen/src/Core/MathFunctions.h
+++ b/Eigen/src/Core/MathFunctions.h
@@ -396,7 +396,7 @@ struct atanh2_default_impl
     using std::log;
     using std::sqrt;
     Scalar z = x / y;
-    if (abs(z) > sqrt(NumTraits<RealScalar>::epsilon()))
+    if (y == Scalar(0) || abs(z) > sqrt(NumTraits<RealScalar>::epsilon()))
       return RealScalar(0.5) * log((y + x) / (y - x));
     else
       return z + z*z*z / RealScalar(3);