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commit change to ctsdfloat

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PABristow
2014-02-11 12:16:28 +00:00
parent cf022a46ec
commit 6bbb7114c2
1 changed files with 168 additions and 19 deletions
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187
example/cstdfloat_example.cpp
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@@ -6,8 +6,6 @@
// Boost Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
/*
/*[cstdfloat_example_1
`This example shows use of a specified-width floating-point typedef
to evaluate a moderately complex math function using
@@ -17,7 +15,7 @@ about 15 decimal digits `std::numeric_limits<boost::float64_t>::digits10`,
The Jahnke Emden lambda function is described at
Weisstein, Eric W. "Lambda Function." From MathWorld--A Wolfram Web Resource.
Weisstein, Eric W. "Lambda Function." From MathWorld--A Wolfram Web Resource.
http://mathworld.wolfram.com/LambdaFunction.html
E. Jahnke and F. Emde, "Tables of Functions with Formulae and Curves,"
@@ -32,6 +30,32 @@ Dover, New York, 4th ed., (1945), pp. 180-188.
#include <boost/cstdfloat.hpp>
#include <boost/math/special_functions.hpp>
/*!
Function max_digits10
Returns maximum number of possibly significant decimal digits for a floating-point type FPT,
even for older compilers/standard libraries that
lack support for std::numeric_limits<FPT>::max_digits10,
when the Kahan formula is used instead.
Also provides the correct result for Visual Studio 2010 where the value provided for float is wrong.
*/
namespace boost
{
template <typename FPT>
int max_digits10()
{
// Since max_digits10 is not defined (or wrong) on older systems, define a local max_digits10.
// Usage: int m = max_digits10<boost::float64_t>();
const int m =
#if (defined BOOST_NO_CXX11_NUMERIC_LIMITS) || (_MSC_VER == 1600) // is wrongly 8 not 9 for VS2010.
2 + std::numeric_limits<FPT>::digits * 3010/10000;
#else
std::numeric_limits<FPT>::max_digits10;
#endif
return m;
}
} // namespace boost
boost::float64_t jahnke_emden_lambda(boost::float64_t v, boost::float64_t x)
{
const boost::float64_t gamma_v_plus_one = boost::math::tgamma(v + 1);
@@ -42,28 +66,142 @@ boost::float64_t jahnke_emden_lambda(boost::float64_t v, boost::float64_t x)
int main()
{
std::cout.setf(std::ios::showpoint); // show all significant trailing zeros.
long double p = 1.L;
//std::cout.precision(std::numeric_limits<long double>::digits10);
std::cout << "pi = " << p << std::endl;
/*[cstdfloat_example_2
`To ensure that all possibly significant digits including trailing zeros are shown.
*/
std::cout.precision(std::numeric_limits<boost::float64_t>::max_digits10);
std::cout.setf(std::ios::showpoint); // show all significant trailing zeros.
try
{ // Always use try'n'catch blocks to ensure any error messages are available.
// Evaluate a sample of the lambda function:
boost::float64_t v = 1.;
boost::float64_t x = 1.;
std::cout << jahnke_emden_lambda(v, x) << std::endl; // 0.88010117148986700
//] [/cstdfloat_example_2]
for (int i = 0; i < 10; i++)
{
std::cout << std::setprecision(2) << boost::float64_t(i) << ' '
std::cout << std::setprecision(2) << boost::float64_t(i) << ' '
<< std::setprecision(std::numeric_limits<boost::float64_t>::max_digits10)
<< jahnke_emden_lambda(boost::float64_t(i), v) << std::endl; //
<< jahnke_emden_lambda(boost::float64_t(i), v) << std::endl; //
}
std::cout << "Floating-point type long double is available." << std::endl;
std::cout << " std::numeric_limits<long double>::digits10 == "
<< std::numeric_limits<long double>::digits10 << std::endl;
std::cout << " std::numeric_limits<long double>::max_digits10 == "
<< std::numeric_limits<long double>::max_digits10 << std::endl; // 21
long double p = boost::math::constants::pi<double>();
std::cout.precision(std::numeric_limits<long double>::digits10);
std::cout << "pi = " << p << std::endl;
// http://www.boost.org/doc/libs/1_54_0/libs/multiprecision/doc/html/boost_multiprecision/tut/floats/float128.html
#ifdef BOOST_FLOAT16_C
std::cout << "Floating-point type boost::float16_t is available." << std::endl;
#else
std::cout << "Floating-point type boost::float16_t is NOT available." << std::endl;
#endif
#ifdef BOOST_FLOAT32_C
std::cout << "Floating-point type boost::float32_t is available." << std::endl;
std::cout << " std::numeric_limits<boost::float32_t>::digits10 == "
<< std::numeric_limits<boost::float32_t>::digits10 << std::endl;
std::cout << " std::numeric_limits<boost::float32_t>::max_digits10 == "
<< std::numeric_limits<boost::float32_t>::max_digits10 << std::endl;
#else
std::cout << "Floating-point type boost::float32_t is NOT available." << std::endl;
#endif
#ifdef BOOST_FLOAT64_C
std::cout << "Floating-point type boost::float64_t is available." << std::endl;
std::cout << " std::numeric_limits<boost::float64_t>::digits10 == "
<< std::numeric_limits<boost::float64_t>::digits10 << std::endl;
std::cout << " std::numeric_limits<boost::float64_t>::max_digits10 == "
<< std::numeric_limits<boost::float64_t>::max_digits10 << std::endl;
#else
std::cout << "Floating-point type boost::float64_t is NOT available." << std::endl;
#endif
#ifdef BOOST_FLOAT80_C
std::cout << "Floating-point type boost::float80_t is available." << std::endl;
std::cout << " std::numeric_limits<boost::float80_t>::digits10 == "
<< std::numeric_limits<boost::float80_t>::digits10 << std::endl;
std::cout << " std::numeric_limits<boost::float80_t>::max_digits10 == "
<< std::numeric_limits<boost::float80_t>::max_digits10 << std::endl;
#else
std::cout << "Floating-point type boost::float80_t is NOT available." << std::endl;
#endif
#ifdef BOOST_FLOAT128_C
std::cout << "Floating-point type boost::float128_t is available." << std::endl;
std::cout << " std::numeric_limits<boost::float128_t>::digits10 == "
<< std::numeric_limits<boost::float128_t>::digits10 << std::endl;
std::cout << " std::numeric_limits<boost::float128_t>::max_digits10 == "
<< std::numeric_limits<boost::float128_t>::max_digits10 << std::endl;
#else
std::cout << "Floating-point type boost::float128_t is NOT available." << std::endl;
#endif
// Show some constants that depend on the available type.
#ifdef BOOST_FLOAT16_C
std::cout.precision(boost::max_digits10<boost::float16_t>()); // Show all significant decimal digits,
std::cout.setf(std::ios::showpoint); // including all significant trailing zeros.
std::cout << "BOOST_FLOAT16_C(123.456789012345678901234567890) = "
<< BOOST_FLOAT16_C(123.456789012345678901234567890) << std::endl;
// BOOST_FLOAT16_C(123.456789012345678901234567890) = 123.45678901234568
#endif
#ifdef BOOST_FLOAT32_C
std::cout.precision(boost::max_digits10<boost::float32_t>()); // Show all significant decimal digits,
std::cout.setf(std::ios::showpoint); // including all significant trailing zeros.
std::cout << "BOOST_FLOAT32_C(123.456789012345678901234567890) = "
<< BOOST_FLOAT32_C(123.456789012345678901234567890) << std::endl;
// BOOST_FLOAT32_C(123.456789012345678901234567890) = 123.456787
#endif
#ifdef BOOST_FLOAT64_C
std::cout.precision(boost::max_digits10<boost::float64_t>()); // Show all significant decimal digits,
std::cout.setf(std::ios::showpoint); // including all significant trailing zeros.
std::cout << "BOOST_FLOAT64_C(123.456789012345678901234567890) = "
<< BOOST_FLOAT64_C(123.456789012345678901234567890) << std::endl;
// BOOST_FLOAT64_C(123.456789012345678901234567890) = 123.45678901234568
#endif
#ifdef BOOST_FLOAT80_C
std::cout.precision(boost::max_digits10<boost::float80_t>()); // Show all significant decimal digits,
std::cout.setf(std::ios::showpoint); // including all significant trailing zeros.
std::cout << "BOOST_FLOAT80_C(123.456789012345678901234567890) = "
<< BOOST_FLOAT80_C(123.456789012345678901234567890) << std::endl;
// BOOST_FLOAT80_C(123.456789012345678901234567890) = 123.456789012345678901234567890000000000000000
#endif
#ifdef BOOST_FLOAT128_C
std::cout.precision(boost::max_digits10<boost::float128_t>()); // Show all significant decimal digits,
std::cout.setf(std::ios::showpoint); // including all significant trailing zeros.
std::cout << "BOOST_FLOAT128_C(123.456789012345678901234567890) = "
<< BOOST_FLOAT128_C(123.456789012345678901234567890) << std::endl;
// BOOST_FLOAT128_C(123.456789012345678901234567890) = 123.456789012345678901234567890000000000000000000
#endif
}
catch (std::exception ex)
{
@@ -75,18 +213,29 @@ int main()
/*
[cstdfloat_output
1.0000000000000000
0.88010117148986700
0.00 0.00000000000000000
1.0 0.88010117148986700
2.0 4.6137984620549854
3.0 16.274830009244948
4.0 -25.360637961042869
5.0 -1257.9038883512258
6.0 -12749.592182518225
7.0 -3020.9830849309396
8.0 2421897.6013183575
9.0 45577595.449204892
0.88010117148986700
0.00 0.00000000000000000
1.0 0.88010117148986700
2.0 4.6137984620549872
3.0 16.274830009244951
4.0 -25.360637961042869
5.0 -1257.9038883512264
6.0 -12749.592182518225
7.0 -3020.9830849309437
8.0 2421897.6013183584
9.0 45577595.449204877
Floating-point type boost::float16_t is NOT available.
Floating-point type boost::float32_t is available.
std::numeric_limits<boost::float32_t>::digits10 == 6
std::numeric_limits<boost::float32_t>::max_digits10 == 9
Floating-point type boost::float64_t is available.
std::numeric_limits<boost::float64_t>::digits10 == 15
std::numeric_limits<boost::float64_t>::max_digits10 == 17
Floating-point type boost::float80_t is NOT available.
Floating-point type boost::float128_t is NOT available.
BOOST_FLOAT32_C(123.456789012345678901234567890) = 123.456787
BOOST_FLOAT64_C(123.456789012345678901234567890) = 123.45678901234568
] [/cstdfloat_output]