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 /*
  [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 , detail::bind( &internal_stepper_base_type::template resize_impl<StateIn> , detail::ref( *this ) , detail::_1 ) );
         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 , detail::bind( &internal_stepper_base_type::template resize_impl< StateInOut > , detail::ref( *this ) , detail::_1 ) );
         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

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