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- // Copyright Nick Thompson, 2017
- // 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 class performs exp-sinh quadrature on half infinite intervals.
- *
- * References:
- *
- * 1) Tanaka, Ken'ichiro, et al. "Function classes for double exponential integration formulas." Numerische Mathematik 111.4 (2009): 631-655.
- */
- #ifndef BOOST_MATH_QUADRATURE_EXP_SINH_HPP
- #define BOOST_MATH_QUADRATURE_EXP_SINH_HPP
- #include <cmath>
- #include <limits>
- #include <memory>
- #include <string>
- #include <boost/math/quadrature/detail/exp_sinh_detail.hpp>
- namespace boost{ namespace math{ namespace quadrature {
- template<class Real, class Policy = policies::policy<> >
- class exp_sinh
- {
- public:
- exp_sinh(size_t max_refinements = 9)
- : m_imp(std::make_shared<detail::exp_sinh_detail<Real, Policy>>(max_refinements)) {}
- template<class F>
- auto integrate(const F& f, Real a, Real b, Real tol = boost::math::tools::root_epsilon<Real>(), Real* error = nullptr, Real* L1 = nullptr, std::size_t* levels = nullptr)->decltype(std::declval<F>()(std::declval<Real>())) const;
- template<class F>
- auto integrate(const F& f, Real tol = boost::math::tools::root_epsilon<Real>(), Real* error = nullptr, Real* L1 = nullptr, std::size_t* levels = nullptr)->decltype(std::declval<F>()(std::declval<Real>())) const;
- private:
- std::shared_ptr<detail::exp_sinh_detail<Real, Policy>> m_imp;
- };
- template<class Real, class Policy>
- template<class F>
- auto exp_sinh<Real, Policy>::integrate(const F& f, Real a, Real b, Real tolerance, Real* error, Real* L1, std::size_t* levels)->decltype(std::declval<F>()(std::declval<Real>())) const
- {
- typedef decltype(f(a)) K;
- using std::abs;
- using boost::math::constants::half;
- using boost::math::quadrature::detail::exp_sinh_detail;
- static const char* function = "boost::math::quadrature::exp_sinh<%1%>::integrate";
- // Neither limit may be a NaN:
- if((boost::math::isnan)(a) || (boost::math::isnan)(b))
- {
- return static_cast<K>(policies::raise_domain_error(function, "NaN supplied as one limit of integration - sorry I don't know what to do", a, Policy()));
- }
- // Right limit is infinite:
- if ((boost::math::isfinite)(a) && (b >= boost::math::tools::max_value<Real>()))
- {
- // If a = 0, don't use an additional level of indirection:
- if (a == (Real) 0)
- {
- return m_imp->integrate(f, error, L1, function, tolerance, levels);
- }
- const auto u = [&](Real t)->K { return f(t + a); };
- return m_imp->integrate(u, error, L1, function, tolerance, levels);
- }
- if ((boost::math::isfinite)(b) && a <= -boost::math::tools::max_value<Real>())
- {
- const auto u = [&](Real t)->K { return f(b-t);};
- return m_imp->integrate(u, error, L1, function, tolerance, levels);
- }
- // Infinite limits:
- if ((a <= -boost::math::tools::max_value<Real>()) && (b >= boost::math::tools::max_value<Real>()))
- {
- return static_cast<K>(policies::raise_domain_error(function, "Use sinh_sinh quadrature for integration over the whole real line; exp_sinh is for half infinite integrals.", a, Policy()));
- }
- // If we get to here then both ends must necessarily be finite:
- return static_cast<K>(policies::raise_domain_error(function, "Use tanh_sinh quadrature for integration over finite domains; exp_sinh is for half infinite integrals.", a, Policy()));
- }
- template<class Real, class Policy>
- template<class F>
- auto exp_sinh<Real, Policy>::integrate(const F& f, Real tolerance, Real* error, Real* L1, std::size_t* levels)->decltype(std::declval<F>()(std::declval<Real>())) const
- {
- static const char* function = "boost::math::quadrature::exp_sinh<%1%>::integrate";
- using std::abs;
- if (abs(tolerance) > 1) {
- std::string msg = std::string(__FILE__) + ":" + std::to_string(__LINE__) + ":" + std::string(function) + ": The tolerance provided is unusually large; did you confuse it with a domain bound?";
- throw std::domain_error(msg);
- }
- return m_imp->integrate(f, error, L1, function, tolerance, levels);
- }
- }}}
- #endif
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