libstdc++-v3/testsuite/tr1/5_numerical_facilities/special_functions/15_expint/pr68397.cc

   1 // Copyright (C) 2017-2019 Free Software Foundation, Inc.
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  15 // with this library; see the file COPYING3.  If not see
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  17
  18 // PR libstdc++/68397 -  std::tr1::expint fails in __expint_En_cont_frac
  19 // for some long double arguments due to low __max_iter value
  20
  21 #include <tr1/cmath>
  22 #include <testsuite_hooks.h>
  23
  24 void
  25 test01()
  26 {
  27   // Answers from Wolfram Alpha.
  28   long double ans_ok = -0.10001943365331651406888645149537315243646135979573L;
  29   long double ans_bomb = -0.10777727809650077516264612749163100483995270163783L;
  30
  31   long double Ei_ok = std::tr1::expint(-1.500001L);
  32   long double diff_ok = std::abs(Ei_ok - ans_ok);
  33   VERIFY(diff_ok < 1.0e-15L);
  34
  35   long double Ei_bomb = std::tr1::expint(-1.450001L);
  36   long double diff_bomb = std::abs(Ei_bomb - ans_bomb);
  37   VERIFY(diff_bomb < 1.0e-15L);
  38 }
  39
  40 int
  41 main()
  42 {
  43   test01();
  44   return 0;
  45 }
  46