From b820b097b870f96538f87862bb3cf22d2b3f4b3b Mon Sep 17 00:00:00 2001
From: Benoit Steiner <benoit.steiner.goog@gmail.com>
Date: Thu, 10 Dec 2015 13:52:05 -0800
Subject: [PATCH] Created EIGEN_HAS_C99_MATH define as Gael suggested.

---
 Eigen/src/Core/util/Macros.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Eigen/src/Core/util/Macros.h b/Eigen/src/Core/util/Macros.h
index 8def69610..d375c77dd 100644
--- a/Eigen/src/Core/util/Macros.h
+++ b/Eigen/src/Core/util/Macros.h
@@ -341,6 +341,13 @@
   #define EIGEN_HAVE_RVALUE_REFERENCES
 #endif
 
+// Does the compiler support C99?
+#if (defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901))       \
+  || (defined(__GNUC__) && defined(_GLIBCXX_USE_C99)) \
+  || (defined(_LIBCPP_VERSION) && !defined(_MSC_VER))
+#define EIGEN_HAS_C99_MATH 1
+#endif
+
 // Does the compiler support result_of?
 #if (__has_feature(cxx_lambdas) || (defined(__cplusplus) && __cplusplus >= 201103L))
 #define EIGEN_HAS_STD_RESULT_OF 1