167 lines
6.6 KiB
Plaintext
167 lines
6.6 KiB
Plaintext
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/*
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[auto_generated]
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boost/numeric/odeint/stepper/euler.hpp
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[begin_description]
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Implementation of the classical explicit Euler stepper. This method is really simple and should only
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be used for demonstration purposes.
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[end_description]
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Copyright 2010-2013 Karsten Ahnert
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Copyright 2010-2013 Mario Mulansky
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE_1_0.txt or
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copy at http://www.boost.org/LICENSE_1_0.txt)
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*/
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#ifndef BOOST_NUMERIC_ODEINT_STEPPER_EULER_HPP_INCLUDED
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#define BOOST_NUMERIC_ODEINT_STEPPER_EULER_HPP_INCLUDED
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#include <boost/numeric/odeint/stepper/base/explicit_stepper_base.hpp>
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#include <boost/numeric/odeint/util/resizer.hpp>
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#include <boost/numeric/odeint/algebra/range_algebra.hpp>
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#include <boost/numeric/odeint/algebra/default_operations.hpp>
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#include <boost/numeric/odeint/algebra/algebra_dispatcher.hpp>
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#include <boost/numeric/odeint/algebra/operations_dispatcher.hpp>
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namespace boost {
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namespace numeric {
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namespace odeint {
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template<
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class State ,
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class Value = double ,
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class Deriv = State ,
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class Time = Value ,
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class Algebra = typename algebra_dispatcher< State >::algebra_type ,
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class Operations = typename operations_dispatcher< State >::operations_type ,
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class Resizer = initially_resizer
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>
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#ifndef DOXYGEN_SKIP
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class euler
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: public explicit_stepper_base<
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euler< State , Value , Deriv , Time , Algebra , Operations , Resizer > ,
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1 , State , Value , Deriv , Time , Algebra , Operations , Resizer >
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#else
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class euler : public explicit_stepper_base
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#endif
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{
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public :
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#ifndef DOXYGEN_SKIP
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typedef explicit_stepper_base< euler< State , Value , Deriv , Time , Algebra , Operations , Resizer > , 1 , State , Value , Deriv , Time , Algebra , Operations , Resizer > stepper_base_type;
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#else
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typedef explicit_stepper_base< euler< ... > , ... > stepper_base_type;
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#endif
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typedef typename stepper_base_type::state_type state_type;
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typedef typename stepper_base_type::value_type value_type;
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typedef typename stepper_base_type::deriv_type deriv_type;
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typedef typename stepper_base_type::time_type time_type;
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typedef typename stepper_base_type::algebra_type algebra_type;
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typedef typename stepper_base_type::operations_type operations_type;
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typedef typename stepper_base_type::resizer_type resizer_type;
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#ifndef DOXYGEN_SKIP
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typedef typename stepper_base_type::stepper_type stepper_type;
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typedef typename stepper_base_type::wrapped_state_type wrapped_state_type;
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typedef typename stepper_base_type::wrapped_deriv_type wrapped_deriv_type;
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#endif
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euler( const algebra_type &algebra = algebra_type() ) : stepper_base_type( algebra )
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{ }
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template< class System , class StateIn , class DerivIn , class StateOut >
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void do_step_impl( System /* system */ , const StateIn &in , const DerivIn &dxdt , time_type /* t */ , StateOut &out , time_type dt )
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{
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stepper_base_type::m_algebra.for_each3( out , in , dxdt ,
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typename operations_type::template scale_sum2< value_type , time_type >( 1.0 , dt ) );
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}
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template< class StateOut , class StateIn1 , class StateIn2 >
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void calc_state( StateOut &x , time_type t , const StateIn1 &old_state , time_type t_old , const StateIn2 & /*current_state*/ , time_type /* t_new */ ) const
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{
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const time_type delta = t - t_old;
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stepper_base_type::m_algebra.for_each3( x , old_state , stepper_base_type::m_dxdt.m_v ,
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typename operations_type::template scale_sum2< value_type , time_type >( 1.0 , delta ) );
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}
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template< class StateType >
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void adjust_size( const StateType &x )
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{
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stepper_base_type::adjust_size( x );
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}
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};
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/********** DOXYGEN ***********/
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/**
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* \class euler
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* \brief An implementation of the Euler method.
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*
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* The Euler method is a very simply solver for ordinary differential equations. This method should not be used
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* for real applications. It is only useful for demonstration purposes. Step size control is not provided but
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* trivial continuous output is available.
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*
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* This class derives from explicit_stepper_base and inherits its interface via CRTP (current recurring template pattern),
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* see explicit_stepper_base
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*
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* \tparam State The state type.
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* \tparam Value The value type.
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* \tparam Deriv The type representing the time derivative of the state.
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* \tparam Time The time representing the independent variable - the time.
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* \tparam Algebra The algebra type.
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* \tparam Operations The operations type.
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* \tparam Resizer The resizer policy type.
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*/
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/**
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* \fn euler::euler( const algebra_type &algebra )
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* \brief Constructs the euler class. This constructor can be used as a default
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* constructor of the algebra has a default constructor.
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* \param algebra A copy of algebra is made and stored inside explicit_stepper_base.
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*/
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/**
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* \fn euler::do_step_impl( System system , const StateIn &in , const DerivIn &dxdt , time_type t , StateOut &out , time_type dt )
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* \brief This method performs one step. The derivative `dxdt` of `in` at the time `t` is passed to the method.
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* The result is updated out of place, hence the input is in `in` and the output in `out`.
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* Access to this step functionality is provided by explicit_stepper_base and
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* `do_step_impl` should not be called directly.
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*
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* \param system The system function to solve, hence the r.h.s. of the ODE. It must fulfill the
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* Simple System concept.
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* \param in The state of the ODE which should be solved. in is not modified in this method
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* \param dxdt The derivative of x at t.
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* \param t The value of the time, at which the step should be performed.
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* \param out The result of the step is written in out.
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* \param dt The step size.
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*/
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/**
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* \fn euler::calc_state( StateOut &x , time_type t , const StateIn1 &old_state , time_type t_old , const StateIn2 ¤t_state , time_type t_new ) const
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* \brief This method is used for continuous output and it calculates the state `x` at a time `t` from the
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* knowledge of two states `old_state` and `current_state` at time points `t_old` and `t_new`.
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*/
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/**
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* \fn euler::adjust_size( const StateType &x )
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* \brief Adjust the size of all temporaries in the stepper manually.
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* \param x A state from which the size of the temporaries to be resized is deduced.
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*/
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} // odeint
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} // numeric
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} // boost
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#endif // BOOST_NUMERIC_ODEINT_STEPPER_EULER_HPP_INCLUDED
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