From c2b706da151ee809f6980182db6a6dc5b0ee0a7d Mon Sep 17 00:00:00 2001
From: jzmaddock <john@johnmaddock.co.uk>
Date: Thu, 3 Sep 2015 18:43:05 +0100
Subject: [PATCH] Add __float128 support.

---
 include/boost/math/tools/promotion.hpp | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/include/boost/math/tools/promotion.hpp b/include/boost/math/tools/promotion.hpp
index b3ad20407..494d7f99e 100644
--- a/include/boost/math/tools/promotion.hpp
+++ b/include/boost/math/tools/promotion.hpp
@@ -86,13 +86,20 @@ namespace boost
 
         typedef typename mpl::if_<
           typename mpl::and_<is_floating_point<T1P>, is_floating_point<T2P> >::type, // both T1P and T2P are floating-point?
-          typename mpl::if_< typename mpl::or_<is_same<long double, T1P>, is_same<long double, T2P> >::type, // either long double?
-            long double, // then result type is long double.
-            typename mpl::if_< typename mpl::or_<is_same<double, T1P>, is_same<double, T2P> >::type, // either double?
-            double, // result type is double.
-          float // else result type is float.
-          >::type
-          >::type,
+#ifdef BOOST_MATH_USE_FLOAT128
+           typename mpl::if_< typename mpl::or_<is_same<__float128, T1P>, is_same<__float128, T2P> >::type, // either long double?
+            __float128,
+#endif
+             typename mpl::if_< typename mpl::or_<is_same<long double, T1P>, is_same<long double, T2P> >::type, // either long double?
+               long double, // then result type is long double.
+               typename mpl::if_< typename mpl::or_<is_same<double, T1P>, is_same<double, T2P> >::type, // either double?
+                  double, // result type is double.
+                  float // else result type is float.
+             >::type
+#ifdef BOOST_MATH_USE_FLOAT128
+             >::type
+#endif
+             >::type,
           // else one or the other is a user-defined type:
           typename mpl::if_< typename mpl::and_<mpl::not_<is_floating_point<T2P> >, ::boost::is_convertible<T1P, T2P> >, T2P, T1P>::type>::type type;
       }; // promote_arg2