boost/libs/math/test/rsqrt_test.cpp
2021-10-05 21:37:46 +02:00

93 lines
2.8 KiB
C++

/*
* Copyright Nick Thompson, 2019
* 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)
*/
#include "math_unit_test.hpp"
#include <numeric>
#include <utility>
#include <random>
#include <cmath>
#include <boost/core/demangle.hpp>
#include <boost/math/special_functions/rsqrt.hpp>
#include <boost/multiprecision/cpp_bin_float.hpp>
#ifdef BOOST_HAS_FLOAT128
#include <boost/multiprecision/float128.hpp>
using boost::multiprecision::float128;
#endif
using boost::math::rsqrt;
template<typename Real>
void test_rsqrt()
{
std::cout << "Testing rsqrt on type " << boost::core::demangle(typeid(Real).name()) << "\n";
using std::sqrt;
Real x = std::numeric_limits<Real>::min();
while (x < 10000*std::numeric_limits<Real>::epsilon()) {
Real expected = 1/sqrt(x);
Real computed = rsqrt(x);
if(!CHECK_ULP_CLOSE(expected, computed, 2)) {
std::cerr << " 1/sqrt(" << x << ") is computed incorrectly.\n";
}
x += std::numeric_limits<Real>::epsilon();
}
// x ~ 1:
x = 1;
while (x < 1 + 1000*std::numeric_limits<Real>::epsilon()) {
Real expected = 1/sqrt(x);
Real computed = rsqrt(x);
if(!CHECK_ULP_CLOSE(expected, computed, 2)) {
std::cerr << " 1/sqrt(" << x << ") is computed incorrectly.\n";
}
x += std::numeric_limits<Real>::epsilon();
}
// x ~ 1000:
x = 1000;
while (x < 1000 + 1000*1000*std::numeric_limits<Real>::epsilon()) {
Real expected = 1/sqrt(x);
Real computed = rsqrt(x);
if(!CHECK_ULP_CLOSE(expected, computed, 2)) {
std::cerr << " 1/sqrt(" << x << ") is computed incorrectly.\n";
}
x += 1000*std::numeric_limits<Real>::epsilon();
}
x = std::numeric_limits<Real>::infinity();
Real expected = 1/sqrt(x);
Real computed = rsqrt(x);
if (!CHECK_ULP_CLOSE(expected, computed, 0)) {
std::cerr << "Reciprocal square root of infinity not correctly computed.\n";
}
x = std::numeric_limits<Real>::max();
expected = 1/sqrt(x);
computed = rsqrt(x);
if (!CHECK_EQUAL(expected, computed)) {
std::cerr << "Reciprocal square root of std::numeric_limits<Real>::max() not correctly computed.\n";
}
if (!CHECK_NAN(rsqrt(std::numeric_limits<Real>::quiet_NaN()))) {
std::cerr << "Reciprocal square root of std::numeric_limits<Real>::quiet_NaN() is not a NaN.\n";
}
}
int main()
{
test_rsqrt<float>();
test_rsqrt<double>();
test_rsqrt<long double>();
test_rsqrt<boost::multiprecision::cpp_bin_float_50>();
test_rsqrt<boost::multiprecision::cpp_bin_float_100>();
#ifdef BOOST_HAS_FLOAT128
test_rsqrt<float128>();
#endif
return boost::math::test::report_errors();
}