ceph/src/boost/libs/math/test/logaddexp_test.cpp

   1 //  (C) Copyright Matt Borland 2022.
   2 //  Distributed under the Boost Software License, Version 1.0.
   3 //  (See accompanying file LICENSE_1_0.txt or copy at
   4 //  http://www.boost.org/LICENSE_1_0.txt)
   5
   6 #include "math_unit_test.hpp"
   7 #include <limits>
   8 #include <boost/math/special_functions/logaddexp.hpp>
   9 #include <boost/math/constants/constants.hpp>
  10
  11 template <typename Real>
  12 void test()
  13 {
  14     using boost::math::logaddexp;
  15     using std::log;
  16     using std::exp;
  17
  18     constexpr Real nan_val = std::numeric_limits<Real>::quiet_NaN();
  19     constexpr Real inf_val = std::numeric_limits<Real>::infinity();
  20
  21     // NAN
  22     CHECK_NAN(logaddexp(nan_val, Real(1)));
  23     CHECK_NAN(logaddexp(Real(1), nan_val));
  24     CHECK_NAN(logaddexp(nan_val, nan_val));
  25
  26     // INF
  27     CHECK_EQUAL(logaddexp(inf_val, Real(1)), inf_val);
  28     CHECK_EQUAL(logaddexp(Real(1), inf_val), inf_val);
  29     CHECK_EQUAL(logaddexp(inf_val, inf_val), inf_val);
  30
  31     // Equal values
  32     constexpr Real ln2 = boost::math::constants::ln_two<Real>();
  33     CHECK_ULP_CLOSE(Real(2) + ln2, logaddexp(Real(2), Real(2)), 1);
  34     CHECK_ULP_CLOSE(Real(1e-50) + ln2, logaddexp(Real(1e-50), Real(1e-50)), 1);
  35
  36     // Spot check
  37     // https://numpy.org/doc/stable/reference/generated/numpy.logaddexp.html
  38     // Calculated at higher precision using wolfram alpha
  39     Real x1 = 1e-50l;
  40     Real x2 = 2.5e-50l;
  41     Real spot1 = static_cast<Real>(exp(x1));
  42     Real spot2 = static_cast<Real>(exp(x2));
  43     Real spot12 = logaddexp(x1, x2);
  44
  45     CHECK_ULP_CLOSE(log(spot1 + spot2), spot12, 1);
  46 }
  47
  48 int main (void)
  49 {
  50     test<float>();
  51     test<double>();
  52     test<long double>();
  53     return boost::math::test::report_errors();
  54 }