boost/numeric/odeint/stepper/base/explicit_stepper_base.hpp
/* [auto_generated] boost/numeric/odeint/stepper/base/explicit_stepper_base.hpp [begin_description] Base class for all explicit Runge Kutta steppers. [end_description] Copyright 2010-2013 Karsten Ahnert Copyright 2010-2012 Mario Mulansky Copyright 2012 Christoph Koke Distributed under 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) */ #ifndef BOOST_NUMERIC_ODEINT_STEPPER_BASE_EXPLICIT_STEPPER_BASE_HPP_INCLUDED #define BOOST_NUMERIC_ODEINT_STEPPER_BASE_EXPLICIT_STEPPER_BASE_HPP_INCLUDED #include <boost/utility/enable_if.hpp> #include <boost/type_traits/is_same.hpp> #include <boost/numeric/odeint/util/bind.hpp> #include <boost/numeric/odeint/util/unwrap_reference.hpp> #include <boost/numeric/odeint/util/state_wrapper.hpp> #include <boost/numeric/odeint/util/resizer.hpp> #include <boost/numeric/odeint/util/is_resizeable.hpp> #include <boost/numeric/odeint/stepper/stepper_categories.hpp> #include <boost/numeric/odeint/stepper/base/algebra_stepper_base.hpp> namespace boost { namespace numeric { namespace odeint { /* * base class for explicit steppers * models the stepper concept * * this class provides the following overloads * do_step( sys , x , t , dt ) * do_step( sys , in , t , out , dt ) * do_step( sys , x , dxdt_in , t , dt ) * do_step( sys , in , dxdt_in , t , out , dt ) */ template< class Stepper , unsigned short Order , class State , class Value , class Deriv , class Time , class Algebra , class Operations , class Resizer > class explicit_stepper_base : public algebra_stepper_base< Algebra , Operations > { public: #ifndef DOXYGEN_SKIP typedef explicit_stepper_base< Stepper , Order , State , Value , Deriv , Time , Algebra , Operations , Resizer > internal_stepper_base_type; #endif // DOXYGEN_SKIP typedef State state_type; typedef Value value_type; typedef Deriv deriv_type; typedef Time time_type; typedef Resizer resizer_type; typedef Stepper stepper_type; typedef stepper_tag stepper_category; typedef algebra_stepper_base< Algebra , Operations > algebra_stepper_base_type; typedef typename algebra_stepper_base_type::algebra_type algebra_type; typedef typename algebra_stepper_base_type::operations_type operations_type; typedef unsigned short order_type; #ifndef DOXYGEN_SKIP typedef state_wrapper< state_type > wrapped_state_type; typedef state_wrapper< deriv_type > wrapped_deriv_type; #endif // DOXYGEN_SKIP static const order_type order_value = Order; explicit_stepper_base( const algebra_type &algebra = algebra_type() ) : algebra_stepper_base_type( algebra ) { } /** * \return Returns the order of the stepper. */ order_type order( void ) const { return order_value; } /* * Version 1 : do_step( sys , x , t , dt ) * * the two overloads are needed in order to solve the forwarding problem */ template< class System , class StateInOut > void do_step( System system , StateInOut &x , time_type t , time_type dt ) { do_step_v1( system , x , t , dt ); } /** * \brief Second version to solve the forwarding problem, can be called with Boost.Range as StateInOut. */ template< class System , class StateInOut > void do_step( System system , const StateInOut &x , time_type t , time_type dt ) { do_step_v1( system , x , t , dt ); } /* * Version 2 : do_step( sys , x , dxdt , t , dt ) * * this version does not solve the forwarding problem, boost.range can not be used * * the disable is needed to avoid ambiguous overloads if state_type = time_type */ template< class System , class StateInOut , class DerivIn > typename boost::disable_if< boost::is_same< DerivIn , time_type > , void >::type do_step( System system , StateInOut &x , const DerivIn &dxdt , time_type t , time_type dt ) { this->stepper().do_step_impl( system , x , dxdt , t , x , dt ); } /* * named Version 2: do_step_dxdt_impl( sys , in , dxdt , t , dt ) * * this version is needed when this stepper is used for initializing * multistep stepper like adams-bashforth. Hence we provide an explicitely * named version that is not disabled. Meant for internal use only. */ template < class System, class StateInOut, class DerivIn > void do_step_dxdt_impl( System system, StateInOut &x, const DerivIn &dxdt, time_type t, time_type dt ) { this->stepper().do_step_impl( system , x , dxdt , t , x , dt ); } /* * Version 3 : do_step( sys , in , t , out , dt ) * * this version does not solve the forwarding problem, boost.range can not be used */ template< class System , class StateIn , class StateOut > void do_step( System system , const StateIn &in , time_type t , StateOut &out , time_type dt ) { typename odeint::unwrap_reference< System >::type &sys = system; m_resizer.adjust_size(in, [this](auto&& arg) { return this->resize_impl<StateIn>(std::forward<decltype(arg)>(arg)); }); sys( in , m_dxdt.m_v ,t ); this->stepper().do_step_impl( system , in , m_dxdt.m_v , t , out , dt ); } /* * Version 4 : do_step( sys , in , dxdt , t , out , dt ) * * this version does not solve the forwarding problem, boost.range can not be used */ template< class System , class StateIn , class DerivIn , class StateOut > void do_step( System system , const StateIn &in , const DerivIn &dxdt , time_type t , StateOut &out , time_type dt ) { this->stepper().do_step_impl( system , in , dxdt , t , out , dt ); } /* * named Version 4: do_step_dxdt_impl( sys , in , dxdt , t , out, dt ) * * this version is needed when this stepper is used for initializing * multistep stepper like adams-bashforth. Hence we provide an explicitely * named version. Meant for internal use only. */ template < class System, class StateIn, class DerivIn, class StateOut > void do_step_dxdt_impl( System system, const StateIn &in, const DerivIn &dxdt, time_type t, StateOut &out, time_type dt ) { this->stepper().do_step_impl( system , in , dxdt , t , out , dt ); } template< class StateIn > void adjust_size( const StateIn &x ) { resize_impl( x ); } private: stepper_type& stepper( void ) { return *static_cast< stepper_type* >( this ); } const stepper_type& stepper( void ) const { return *static_cast< const stepper_type* >( this ); } template< class StateIn > bool resize_impl( const StateIn &x ) { return adjust_size_by_resizeability( m_dxdt , x , typename is_resizeable<deriv_type>::type() ); } template< class System , class StateInOut > void do_step_v1( System system , StateInOut &x , time_type t , time_type dt ) { typename odeint::unwrap_reference< System >::type &sys = system; m_resizer.adjust_size(x, [this](auto&& arg) { return this->resize_impl<StateInOut>(std::forward<decltype(arg)>(arg)); }); sys( x , m_dxdt.m_v ,t ); this->stepper().do_step_impl( system , x , m_dxdt.m_v , t , x , dt ); } resizer_type m_resizer; protected: wrapped_deriv_type m_dxdt; }; /******* DOXYGEN *********/ /** * \class explicit_stepper_base * \brief Base class for explicit steppers without step size control and without dense output. * * This class serves as the base class for all explicit steppers with algebra and operations. * Step size control and error estimation as well as dense output are not provided. explicit_stepper_base * is used as the interface in a CRTP (currently recurring template pattern). In order to work * correctly the parent class needs to have a method `do_step_impl( system , in , dxdt_in , t , out , dt )`. * This is method is used by explicit_stepper_base. explicit_stepper_base derives from * algebra_stepper_base. An example how this class can be used is * * \code * template< class State , class Value , class Deriv , class Time , class Algebra , class Operations , class Resizer > * class custom_euler : public explicit_stepper_base< 1 , State , Value , Deriv , Time , Algebra , Operations , Resizer > * { * public: * * typedef explicit_stepper_base< 1 , State , Value , Deriv , Time , Algebra , Operations , Resizer > base_type; * * custom_euler( const Algebra &algebra = Algebra() ) { } * * template< class Sys , class StateIn , class DerivIn , class StateOut > * void do_step_impl( Sys sys , const StateIn &in , const DerivIn &dxdt , Time t , StateOut &out , Time dt ) * { * m_algebra.for_each3( out , in , dxdt , Operations::scale_sum2< Value , Time >( 1.0 , dt ); * } * * template< class State > * void adjust_size( const State &x ) * { * base_type::adjust_size( x ); * } * }; * \endcode * * For the Stepper concept only the `do_step( sys , x , t , dt )` needs to be implemented. But this class * provides additional `do_step` variants since the stepper is explicit. These methods can be used to increase * the performance in some situation, for example if one needs to analyze `dxdt` during each step. In this case * one can use * * \code * sys( x , dxdt , t ); * stepper.do_step( sys , x , dxdt , t , dt ); // the value of dxdt is used here * t += dt; * \endcode * * In detail explicit_stepper_base provides the following `do_step` variants * - `do_step( sys , x , t , dt )` - The classical `do_step` method needed to fulfill the Stepper concept. The state is updated in-place. * A type modelling a Boost.Range can be used for x. * - `do_step( sys , in , t , out , dt )` - This method updates the state out-of-place, hence the result of the step is stored in `out`. * - `do_step( sys , x , dxdt , t , dt )` - This method updates the state in-place, but the derivative at the point `t` must be * explicitly passed in `dxdt`. For an example see the code snippet above. * - `do_step( sys , in , dxdt , t , out , dt )` - This method update the state out-of-place and expects that the derivative at the point * `t` is explicitly passed in `dxdt`. It is a combination of the two `do_step` methods above. * * \note The system is always passed as value, which might result in poor performance if it contains data. In this case it can be used with `boost::ref` * or `std::ref`, for example `stepper.do_step( boost::ref( sys ) , x , t , dt );` * * \note The time `t` is not advanced by the stepper. This has to done manually, or by the appropriate `integrate` routines or `iterator`s. * * \tparam Stepper The stepper on which this class should work. It is used via CRTP, hence explicit_stepper_base * provides the interface for the Stepper. * \tparam Order The order of the stepper. * \tparam State The state type for the stepper. * \tparam Value The value type for the stepper. This should be a floating point type, like float, * double, or a multiprecision type. It must not necessary be the value_type of the State. For example * the State can be a `vector< complex< double > >` in this case the Value must be double. * The default value is double. * \tparam Deriv The type representing time derivatives of the state type. It is usually the same type as the * state type, only if used with Boost.Units both types differ. * \tparam Time The type representing the time. Usually the same type as the value type. When Boost.Units is * used, this type has usually a unit. * \tparam Algebra The algebra type which must fulfill the Algebra Concept. * \tparam Operations The type for the operations which must fulfill the Operations Concept. * \tparam Resizer The resizer policy class. */ /** * \fn explicit_stepper_base::explicit_stepper_base( const algebra_type &algebra ) * \brief Constructs a explicit_stepper_base class. This constructor can be used as a default * constructor if the algebra has a default constructor. * \param algebra A copy of algebra is made and stored inside explicit_stepper_base. */ /** * \fn explicit_stepper_base::order_type order( void ) const * \return Returns the order of the stepper. */ /** * \fn explicit_stepper_base::do_step( System system , StateInOut &x , time_type t , time_type dt ) * \brief This method performs one step. It transforms the result in-place. * * \param system The system function to solve, hence the r.h.s. of the ordinary differential equation. It must fulfill the * Simple System concept. * \param x The state of the ODE which should be solved. After calling do_step the result is updated in x. * \param t The value of the time, at which the step should be performed. * \param dt The step size. */ /** * \fn explicit_stepper_base::do_step( System system , StateInOut &x , const DerivIn &dxdt , time_type t , time_type dt ) * \brief The method performs one step. Additionally to the other method * the derivative of x is also passed to this method. It is supposed to be used in the following way: * * \code * sys( x , dxdt , t ); * stepper.do_step( sys , x , dxdt , t , dt ); * \endcode * * The result is updated in place in x. This method is disabled if Time and Deriv are of the same type. In this * case the method could not be distinguished from other `do_step` versions. * * \note This method does not solve the forwarding problem. * * \param system The system function to solve, hence the r.h.s. of the ODE. It must fulfill the * Simple System concept. * \param x The state of the ODE which should be solved. After calling do_step the result is updated in x. * \param dxdt The derivative of x at t. * \param t The value of the time, at which the step should be performed. * \param dt The step size. */ /** * \fn void explicit_stepper_base::do_step( System system , const StateIn &in , time_type t , StateOut &out , time_type dt ) * \brief The method performs one step. The state of the ODE is updated out-of-place. * \note This method does not solve the forwarding problem. * * \param system The system function to solve, hence the r.h.s. of the ODE. It must fulfill the * Simple System concept. * \param in The state of the ODE which should be solved. in is not modified in this method * \param t The value of the time, at which the step should be performed. * \param out The result of the step is written in out. * \param dt The step size. */ /** * \fn void explicit_stepper_base::do_step( System system , const StateIn &in , const DerivIn &dxdt , time_type t , StateOut &out , time_type dt ) * \brief The method performs one step. The state of the ODE is updated out-of-place. * Furthermore, the derivative of x at t is passed to the stepper. * It is supposed to be used in the following way: * * \code * sys( in , dxdt , t ); * stepper.do_step( sys , in , dxdt , t , out , dt ); * \endcode * * \note This method does not solve the forwarding problem. * * \param system The system function to solve, hence the r.h.s. of the ODE. It must fulfill the * Simple System concept. * \param in The state of the ODE which should be solved. in is not modified in this method * \param dxdt The derivative of x at t. * \param t The value of the time, at which the step should be performed. * \param out The result of the step is written in out. * \param dt The step size. */ /** * \fn void explicit_stepper_base::adjust_size( const StateIn &x ) * \brief Adjust the size of all temporaries in the stepper manually. * \param x A state from which the size of the temporaries to be resized is deduced. */ } // odeint } // numeric } // boost #endif // BOOST_NUMERIC_ODEINT_STEPPER_BASE_EXPLICIT_STEPPER_BASE_HPP_INCLUDED