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/*
[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
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