Subject: [Boost-commit] svn:boost r82899 - trunk/libs/math/example
From: pbristow_at_[hidden]
Date: 2013-02-15 05:49:15
Author: pbristow
Date: 2013-02-15 05:49:15 EST (Fri, 15 Feb 2013)
New Revision: 82899
URL: http://svn.boost.org/trac/boost/changeset/82899
Log:
use Kahan formula where max_digits10 not available.
Text files modified:
trunk/libs/math/example/constants_eg1.cpp | 18 ++++++++++++------
1 files changed, 12 insertions(+), 6 deletions(-)
Modified: trunk/libs/math/example/constants_eg1.cpp
==============================================================================
--- trunk/libs/math/example/constants_eg1.cpp (original)
+++ trunk/libs/math/example/constants_eg1.cpp 2013-02-15 05:49:15 EST (Fri, 15 Feb 2013)
@@ -1,4 +1,4 @@
-// Copyright Paul Bristow 2012.
+// Copyright Paul Bristow 2013.
// Copyright John Maddock 2010.
// Use, modification and distribution are subject to the
@@ -42,14 +42,20 @@
int main()
{
-
+
{ // Boost.Math constants using function calls like pi().
// using namespace boost::math::constants;
-
+
using boost::math::constants::pi;
using boost::math::constants::one_div_two_pi;
- cout.precision(numeric_limits<double>::max_digits10);
+#ifdef BOOST_NO_CXX11_NUMERIC_LIMITS
+ std::size_t max_digits10 = 2 + std::numeric_limits<double>::digits * 3010/10000;
+#else
+ std::size_t max_digits10 = std::numeric_limits<double>::max_digits10;
+#endif
+
+ std::cout.precision(max_digits10);
cout << "double pi = boost::math::double_constants::pi = " << pi<double>() << endl;
// double pi = boost::math::double_constants::pi = 3.1415926535897931
double r = 1.234567890123456789;
@@ -83,7 +89,7 @@
double my2pi = two_pi; // Uses boost::math::double_constants::two_pi;
cout << "double my2pi = " << my2pi << endl;
-
+
using boost::math::float_constants::e;
float my_e = e;
cout << "float my_e " << my_e << endl;
@@ -138,7 +144,7 @@
// For example, naively providing an @b integer instead of a floating-point type can be disastrous.
// cout << "Area = " << area(2) << endl; // warning : 'return' : conversion from 'double' to 'int', possible loss of data
// Failure to heed this warning can lead to very wrong answers!
- // Area = 12 !! = 3 * 2 * 2
+ // Area = 12 !! = 3 * 2 * 2
//[math_constants_template_integer_type
//cout << "Area = " << area(2) << endl; // Area = 12!
cout << "Area = " << area(2.) << endl; // Area = 12.566371