| /* |
| [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 & /*current_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 |