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

   1 // Copyright Nick Thompson, 2020
   2 // Use, modification and distribution are subject to the
   3 // Boost Software License, Version 1.0.
   4 // (See accompanying file LICENSE_1_0.txt
   5 // or copy at http://www.boost.org/LICENSE_1_0.txt)
   6 #include "math_unit_test.hpp"
   7 #include <boost/math/quadrature/tanh_sinh.hpp>
   8 #include <boost/math/constants/constants.hpp>
   9 #include <boost/multiprecision/mpfr.hpp>
  10
  11 using std::log;
  12 using std::sin;
  13 using std::abs;
  14 using boost::math::quadrature::tanh_sinh;
  15 using boost::multiprecision::mpfr_float;
  16 using boost::math::constants::pi;
  17 using boost::math::constants::zeta_three;
  18
  19 int main() {
  20     using Real = mpfr_float;
  21     int p = 100;
  22     mpfr_float::default_precision(p);
  23     auto f = [](Real x)->Real { return x*log(sin(x)); };
  24     auto integrator = tanh_sinh<mpfr_float>();
  25     Real Q = integrator.integrate(f, Real(0), pi<Real>()/2);
  26     // Sanity check: NIntegrate[x*Log[Sin[x]],{x,0,Pi/2}] = -0.329236
  27     Real expected = (7*zeta_three<Real>() - pi<Real>()*pi<Real>()*log(static_cast<Real>(4)))/16;
  28     CHECK_ULP_CLOSE(expected, Q, 3);
  29     return boost::math::test::report_errors();
  30 }