math/test/erf_limits_test.cpp
2021-11-01 19:24:31 +00:00

74 lines
2.4 KiB
C++

// (C) Copyright John Maddock 2021.
// Use, modification and distribution are subject to the
// Boost Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// This test verifies that the limits we use in the numerical approximations to erf/erc
// are indeed correct. The values tested must of course match the values used in erf.hpp.
// See https://github.com/boostorg/math/issues/710
//
#define BOOST_TEST_MODULE erf_limits
#include <boost/multiprecision/cpp_bin_float.hpp>
#include <boost/math/special_functions/erf.hpp>
#include <boost/test/included/unit_test.hpp>
#include <cfloat>
BOOST_AUTO_TEST_CASE(limits_53_digits)
{
double arg = 5.93f;
double t = (double)boost::math::erf(boost::multiprecision::cpp_bin_float_50(arg));
BOOST_CHECK_EQUAL(t, 1.0);
arg = 5.9;
BOOST_CHECK_LT(boost::math::erf(arg), 1.0);
arg = 28;
t = (double)boost::math::erfc(boost::multiprecision::cpp_bin_float_50(arg));
BOOST_CHECK_EQUAL(t, 0.0);
arg = 27.2;
BOOST_CHECK_GT(boost::math::erfc(arg), 0.0);
}
BOOST_AUTO_TEST_CASE(limits_64_digits)
{
float arg = 6.6f;
boost::multiprecision::cpp_bin_float_double_extended t = (boost::multiprecision::cpp_bin_float_double_extended)boost::math::erf(boost::multiprecision::cpp_bin_float_50(arg));
BOOST_CHECK_EQUAL(t, 1.0);
#if (LDBL_MANT_DIG == 64) && !defined(BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS)
arg = 6.5;
BOOST_CHECK_LT(boost::math::erf(static_cast<long double>(arg)), 1.0L);
#endif
arg = 110;
t = (boost::multiprecision::cpp_bin_float_double_extended)boost::math::erfc(boost::multiprecision::cpp_bin_float_50(arg));
BOOST_CHECK_EQUAL(t, 0.0);
#if (LDBL_MANT_DIG == 64) && !defined(BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS)
arg = 106.5;
BOOST_CHECK_GT(boost::math::erfc(static_cast<long double>(arg)), 0.0L);
#endif
}
BOOST_AUTO_TEST_CASE(limits_113_digits)
{
//
// This limit is not actually used in the code, logged here for future reference...
//
float arg = 8.8f;
boost::multiprecision::cpp_bin_float_quad t = (boost::multiprecision::cpp_bin_float_quad)boost::math::erf(boost::multiprecision::cpp_bin_float_50(arg));
BOOST_CHECK_EQUAL(t, 1.0);
arg = 110;
t = (boost::multiprecision::cpp_bin_float_quad)boost::math::erfc(boost::multiprecision::cpp_bin_float_50(arg));
BOOST_CHECK_EQUAL(t, 0.0);
}