[Boost-commit] svn:boost r82920 - in trunk: boost/multiprecision libs/multiprecision/test

Subject: [Boost-commit] svn:boost r82920 - in trunk: boost/multiprecision libs/multiprecision/test
From: e_float_at_[hidden]
Date: 2013-02-16 05:55:07

Author: christopher_kormanyos
Date: 2013-02-16 05:55:06 EST (Sat, 16 Feb 2013)
New Revision: 82920
URL: http://svn.boost.org/trac/boost/changeset/82920

Log:
Refs #8065
Added:
   trunk/libs/multiprecision/test/test_cpp_dec_float_round.cpp   (contents, props changed)
Text files modified: 
   trunk/boost/multiprecision/cpp_dec_float.hpp |     9 +++------                               
   trunk/libs/multiprecision/test/Jamfile.v2    |     2 ++                                      
   2 files changed, 5 insertions(+), 6 deletions(-)

Modified: trunk/boost/multiprecision/cpp_dec_float.hpp
==============================================================================
--- trunk/boost/multiprecision/cpp_dec_float.hpp	(original)
+++ trunk/boost/multiprecision/cpp_dec_float.hpp	2013-02-16 05:55:06 EST (Sat, 16 Feb 2013)
@@ -1720,12 +1720,9 @@
       // Thus the integer part is zero.
       return zero();
    }
-   else if(exp >= static_cast<ExponentType>(Digits10 - 1))
-   {
-      // The number is too large to resolve the integer part.
-      // Thus it is already a pure integer part.
-      return *this;
-   }
+
+   // Truncate the digits from the decimal part, including guard digits
+   // that do not belong to the integer part.
 
    // Make a local copy.
    cpp_dec_float<Digits10, ExponentType, Allocator> x = *this;

Modified: trunk/libs/multiprecision/test/Jamfile.v2
==============================================================================
--- trunk/libs/multiprecision/test/Jamfile.v2	(original)
+++ trunk/libs/multiprecision/test/Jamfile.v2	2013-02-16 05:55:06 EST (Sat, 16 Feb 2013)
@@ -101,6 +101,8 @@
 run test_arithmetic_ab_2.cpp ;
 run test_arithmetic_ab_3.cpp ;
 
+run test_cpp_dec_float_round.cpp ;
+
 run test_arithmetic_logged_1.cpp ;
 run test_arithmetic_logged_2.cpp ;
 

Added: trunk/libs/multiprecision/test/test_cpp_dec_float_round.cpp
==============================================================================
--- (empty file)
+++ trunk/libs/multiprecision/test/test_cpp_dec_float_round.cpp	2013-02-16 05:55:06 EST (Sat, 16 Feb 2013)
@@ -0,0 +1,67 @@
+///////////////////////////////////////////////////////////////
+//  Copyright 2013 Christopher Kormanyos. Distributed under the Boost
+//  Software License, Version 1.0. (See accompanying file
+//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_
+//
+
+// Test case for ticket:
+// #8065: Multiprecision rounding issue
+
+#ifdef _MSC_VER
+#  define _SCL_SECURE_NO_WARNINGS
+#endif
+
+#include <boost/detail/lightweight_test.hpp>
+#include "test.hpp"
+#include <boost/multiprecision/cpp_dec_float.hpp>
+#include <boost/math/special_functions/round.hpp>
+
+template<int N>
+static bool round_test_imp()
+{
+  typedef boost::multiprecision::cpp_dec_float<N> mp_backend_type;
+  typedef boost::multiprecision::number<mp_backend_type, boost::multiprecision::et_off> mp_type;
+
+  const mp_type original_digits(1.0F);
+
+  const mp_type scale = pow(mp_type(10), N);
+
+  mp_type these_digits = original_digits * scale;
+
+  these_digits  = boost::math::round(these_digits);
+  these_digits /= scale;
+
+  const std::string result = these_digits.str();
+
+  return (result == original_digits.str());
+}
+
+template<int N>
+struct round_test
+{
+  static bool test()
+  {
+    return (round_test_imp<N>() && round_test<N - 1>::test());
+  }
+};
+
+template<>
+struct round_test<0>
+{
+  static bool test()
+  {
+    return round_test_imp<0>();
+  }
+};
+
+int main()
+{
+   //
+   // Test cpp_dec_float rounding with boost::math::round() at various precisions:
+   //
+   const bool round_test_result = round_test<40>::test();
+
+   BOOST_CHECK_EQUAL(round_test_result, true);
+
+   return boost::report_errors();
+}