From fb3aa7220f10a1ed7f5f41e57260889017974297 Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Tue, 8 Nov 2011 22:42:51 +0100
Subject: [PATCH] reimplement abs2 not to use std::norm which is incredibly
 slow.

---
 Eigen/src/Core/MathFunctions.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/Eigen/src/Core/MathFunctions.h b/Eigen/src/Core/MathFunctions.h
index 2b454db21..b4a4c8905 100644
--- a/Eigen/src/Core/MathFunctions.h
+++ b/Eigen/src/Core/MathFunctions.h
@@ -309,8 +309,7 @@ struct abs2_impl<std::complex<RealScalar> >
 {
   static inline RealScalar run(const std::complex<RealScalar>& x)
   {
-    using std::norm;
-    return norm(x);
+    return real(x)*real(x) + imag(x)*imag(x);
   }
 };