[Boost-commit] svn:boost r84997 - in trunk: boost/multiprecision/detail/functions libs/multiprecision/test

Subject: [Boost-commit] svn:boost r84997 - in trunk: boost/multiprecision/detail/functions libs/multiprecision/test
From: john_at_[hidden]
Date: 2013-07-10 12:08:13

Author: johnmaddock
Date: 2013-07-10 12:08:12 EDT (Wed, 10 Jul 2013)
New Revision: 84997
URL: http://svn.boost.org/trac/boost/changeset/84997

Log:
Fix bug in eval_pow that causes 0^N to be none-zero.
Fixes #8798.

Text files modified: 
   trunk/boost/multiprecision/detail/functions/pow.hpp |    13 ++++++++++++-                           
   trunk/libs/multiprecision/test/test_pow.cpp         |    11 +++++++++++                             
   2 files changed, 23 insertions(+), 1 deletions(-)

Modified: trunk/boost/multiprecision/detail/functions/pow.hpp
==============================================================================
--- trunk/boost/multiprecision/detail/functions/pow.hpp	Wed Jul 10 02:44:14 2013	(r84996)
+++ trunk/boost/multiprecision/detail/functions/pow.hpp	2013-07-10 12:08:12 EDT (Wed, 10 Jul 2013)	(r84997)
@@ -427,7 +427,18 @@
       result = x;
       return;
    case FP_ZERO:
-      result = si_type(1);
+      switch(eval_fpclassify(a))
+      {
+      case FP_ZERO:
+         result = si_type(1);
+         break;
+      case FP_NAN:
+         result = a;
+         break;
+      default:
+         result = x;
+         break;
+      }
       return;
    case FP_NAN:
       result = x;

Modified: trunk/libs/multiprecision/test/test_pow.cpp
==============================================================================
--- trunk/libs/multiprecision/test/test_pow.cpp	Wed Jul 10 02:44:14 2013	(r84996)
+++ trunk/libs/multiprecision/test/test_pow.cpp	2013-07-10 12:08:12 EDT (Wed, 10 Jul 2013)	(r84997)
@@ -572,6 +572,17 @@
       }
    }
    std::cout << "Max error was: " << max_err << std::endl;
+   //
+   // Special cases come last:
+   //
+   BOOST_CHECK_EQUAL(pow(T(0), T(0)), 1);
+   BOOST_CHECK_EQUAL(pow(T(0), 0), 1);
+   BOOST_CHECK_EQUAL(pow(T(0), T(2)), 0);
+   BOOST_CHECK_EQUAL(pow(T(0), 2), 0);
+   BOOST_CHECK_EQUAL(pow(T(1), T(0)), 1);
+   BOOST_CHECK_EQUAL(pow(T(1), 0), 1);
+   BOOST_CHECK_EQUAL(pow(T(1), T(2)), 1);
+   BOOST_CHECK_EQUAL(pow(T(1), 2), 1);
 }