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Diffstat (limited to 'boost/numeric/odeint/stepper/euler.hpp')
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1 files changed, 166 insertions, 0 deletions
diff --git a/boost/numeric/odeint/stepper/euler.hpp b/boost/numeric/odeint/stepper/euler.hpp new file mode 100644 index 0000000000..443f942763 --- /dev/null +++ b/boost/numeric/odeint/stepper/euler.hpp @@ -0,0 +1,166 @@ +/* + [auto_generated] + boost/numeric/odeint/stepper/euler.hpp + + [begin_description] + Implementation of the classical explicit Euler stepper. This method is really simple and should only + be used for demonstration purposes. + [end_description] + + Copyright 2010-2013 Karsten Ahnert + Copyright 2010-2013 Mario Mulansky + + 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_EULER_HPP_INCLUDED +#define BOOST_NUMERIC_ODEINT_STEPPER_EULER_HPP_INCLUDED + + +#include <boost/numeric/odeint/stepper/base/explicit_stepper_base.hpp> +#include <boost/numeric/odeint/util/resizer.hpp> +#include <boost/numeric/odeint/algebra/range_algebra.hpp> +#include <boost/numeric/odeint/algebra/default_operations.hpp> +#include <boost/numeric/odeint/algebra/algebra_dispatcher.hpp> +#include <boost/numeric/odeint/algebra/operations_dispatcher.hpp> + +namespace boost { +namespace numeric { +namespace odeint { + + +template< +class State , +class Value = double , +class Deriv = State , +class Time = Value , +class Algebra = typename algebra_dispatcher< State >::algebra_type , +class Operations = typename operations_dispatcher< State >::operations_type , +class Resizer = initially_resizer +> +#ifndef DOXYGEN_SKIP +class euler +: public explicit_stepper_base< + euler< State , Value , Deriv , Time , Algebra , Operations , Resizer > , + 1 , State , Value , Deriv , Time , Algebra , Operations , Resizer > +#else +class euler : public explicit_stepper_base +#endif +{ +public : + + #ifndef DOXYGEN_SKIP + typedef explicit_stepper_base< euler< State , Value , Deriv , Time , Algebra , Operations , Resizer > , 1 , State , Value , Deriv , Time , Algebra , Operations , Resizer > stepper_base_type; + #else + typedef explicit_stepper_base< euler< ... > , ... > stepper_base_type; + #endif + typedef typename stepper_base_type::state_type state_type; + typedef typename stepper_base_type::value_type value_type; + typedef typename stepper_base_type::deriv_type deriv_type; + typedef typename stepper_base_type::time_type time_type; + typedef typename stepper_base_type::algebra_type algebra_type; + typedef typename stepper_base_type::operations_type operations_type; + typedef typename stepper_base_type::resizer_type resizer_type; + + #ifndef DOXYGEN_SKIP + typedef typename stepper_base_type::stepper_type stepper_type; + typedef typename stepper_base_type::wrapped_state_type wrapped_state_type; + typedef typename stepper_base_type::wrapped_deriv_type wrapped_deriv_type; + #endif + + + euler( const algebra_type &algebra = algebra_type() ) : stepper_base_type( algebra ) + { } + + template< class System , class StateIn , class DerivIn , class StateOut > + void do_step_impl( System system , const StateIn &in , const DerivIn &dxdt , time_type t , StateOut &out , time_type dt ) + { + stepper_base_type::m_algebra.for_each3( out , in , dxdt , + typename operations_type::template scale_sum2< value_type , time_type >( 1.0 , dt ) ); + + } + + template< class StateOut , class StateIn1 , class StateIn2 > + void calc_state( StateOut &x , time_type t , const StateIn1 &old_state , time_type t_old , const StateIn2 ¤t_state , time_type t_new ) const + { + const time_type delta = t - t_old; + stepper_base_type::m_algebra.for_each3( x , old_state , stepper_base_type::m_dxdt.m_v , + typename operations_type::template scale_sum2< value_type , time_type >( 1.0 , delta ) ); + } + + template< class StateType > + void adjust_size( const StateType &x ) + { + stepper_base_type::adjust_size( x ); + } +}; + + + +/********** DOXYGEN ***********/ + +/** + * \class euler + * \brief An implementation of the Euler method. + * + * The Euler method is a very simply solver for ordinary differential equations. This method should not be used + * for real applications. It is only useful for demonstration purposes. Step size control is not provided but + * trivial continuous output is available. + * + * This class derives from explicit_stepper_base and inherits its interface via CRTP (current recurring template pattern), + * see explicit_stepper_base + * + * \tparam State The state type. + * \tparam Value The value type. + * \tparam Deriv The type representing the time derivative of the state. + * \tparam Time The time representing the independent variable - the time. + * \tparam Algebra The algebra type. + * \tparam Operations The operations type. + * \tparam Resizer The resizer policy type. + */ + + /** + * \fn euler::euler( const algebra_type &algebra ) + * \brief Constructs the euler class. This constructor can be used as a default + * constructor of the algebra has a default constructor. + * \param algebra A copy of algebra is made and stored inside explicit_stepper_base. + */ + + /** + * \fn euler::do_step_impl( System system , const StateIn &in , const DerivIn &dxdt , time_type t , StateOut &out , time_type dt ) + * \brief This method performs one step. The derivative `dxdt` of `in` at the time `t` is passed to the method. + * The result is updated out of place, hence the input is in `in` and the output in `out`. + * Access to this step functionality is provided by explicit_stepper_base and + * `do_step_impl` should not be called directly. + * + * \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 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 + * \brief This method is used for continuous output and it calculates the state `x` at a time `t` from the + * knowledge of two states `old_state` and `current_state` at time points `t_old` and `t_new`. + */ + + /** + * \fn euler::adjust_size( const StateType &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_EULER_HPP_INCLUDED |