From 59eb0f44df227d09313ed91fb4a6fe85c9ff0e22 Mon Sep 17 00:00:00 2001
From: John Maddock <john@johnmaddock.co.uk>
Date: Sat, 28 Jan 2012 19:13:44 +0000
Subject: [PATCH] Don't be too quick to disable long double functions if
 __NO_LONG_DOUBLE_MATH is set by GLIBC. Fixes #6459.

[SVN r76764]
---
 include/boost/math/tools/config.hpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/boost/math/tools/config.hpp b/include/boost/math/tools/config.hpp
index 96f5d81a4..937de15f3 100644
--- a/include/boost/math/tools/config.hpp
+++ b/include/boost/math/tools/config.hpp
@@ -16,6 +16,7 @@
 #include <algorithm>  // for min and max
 #include <boost/config/no_tr1/cmath.hpp>
 #include <climits>
+#include <cfloat>
 #if (defined(macintosh) || defined(__APPLE__) || defined(__APPLE_CC__))
 #  include <math.h>
 #endif
@@ -24,7 +25,8 @@
 #include <boost/math/special_functions/detail/round_fwd.hpp>
 
 #if (defined(__CYGWIN__) || defined(__FreeBSD__) || defined(__NetBSD__) \
-   || (defined(__hppa) && !defined(__OpenBSD__)) || defined(__NO_LONG_DOUBLE_MATH)) && !defined(BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS)
+   || (defined(__hppa) && !defined(__OpenBSD__)) || (defined(__NO_LONG_DOUBLE_MATH) && (DBL_MANT_DIG != LDBL_MANT_DIG))) \
+   && !defined(BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS)
 #  define BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
 #endif
 #if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x582))