| /* |
| [auto_generated] |
| boost/numeric/odeint/stepper/velocity_verlet.hpp |
| |
| [begin_description] |
| tba. |
| [end_description] |
| |
| Copyright 2009-2012 Karsten Ahnert |
| Copyright 2009-2012 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_VELOCITY_VERLET_HPP_DEFINED |
| #define BOOST_NUMERIC_ODEINT_STEPPER_VELOCITY_VERLET_HPP_DEFINED |
| |
| #include <boost/numeric/odeint/stepper/base/algebra_stepper_base.hpp> |
| #include <boost/numeric/odeint/stepper/stepper_categories.hpp> |
| |
| #include <boost/numeric/odeint/algebra/algebra_dispatcher.hpp> |
| #include <boost/numeric/odeint/algebra/operations_dispatcher.hpp> |
| #include <boost/numeric/odeint/util/resizer.hpp> |
| #include <boost/numeric/odeint/util/state_wrapper.hpp> |
| #include <boost/numeric/odeint/util/unwrap_reference.hpp> |
| |
| #include <boost/numeric/odeint/util/bind.hpp> |
| #include <boost/numeric/odeint/util/copy.hpp> |
| #include <boost/numeric/odeint/util/resizer.hpp> |
| // #include <boost/numeric/odeint/util/is_pair.hpp> |
| // #include <boost/array.hpp> |
| |
| |
| |
| namespace boost { |
| namespace numeric { |
| namespace odeint { |
| |
| |
| |
| template < |
| class Coor , |
| class Velocity = Coor , |
| class Value = double , |
| class Acceleration = Coor , |
| class Time = Value , |
| class TimeSq = Time , |
| class Algebra = typename algebra_dispatcher< Coor >::algebra_type , |
| class Operations = typename operations_dispatcher< Coor >::operations_type , |
| class Resizer = initially_resizer |
| > |
| class velocity_verlet : public algebra_stepper_base< Algebra , Operations > |
| { |
| public: |
| |
| 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 Coor coor_type; |
| typedef Velocity velocity_type; |
| typedef Acceleration acceleration_type; |
| typedef std::pair< coor_type , velocity_type > state_type; |
| typedef std::pair< velocity_type , acceleration_type > deriv_type; |
| typedef state_wrapper< acceleration_type > wrapped_acceleration_type; |
| typedef Value value_type; |
| typedef Time time_type; |
| typedef TimeSq time_square_type; |
| typedef Resizer resizer_type; |
| typedef stepper_tag stepper_category; |
| |
| typedef unsigned short order_type; |
| |
| static const order_type order_value = 1; |
| |
| /** |
| * \return Returns the order of the stepper. |
| */ |
| order_type order( void ) const |
| { |
| return order_value; |
| } |
| |
| |
| velocity_verlet( const algebra_type & algebra = algebra_type() ) |
| : algebra_stepper_base_type( algebra ) , m_first_call( true ) |
| , m_a1() , m_a2() , m_current_a1( true ) { } |
| |
| |
| 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 ); |
| } |
| |
| |
| 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 ); |
| } |
| |
| |
| template< class System , class CoorIn , class VelocityIn , class AccelerationIn , |
| class CoorOut , class VelocityOut , class AccelerationOut > |
| void do_step( System system , CoorIn const & qin , VelocityIn const & pin , AccelerationIn const & ain , |
| CoorOut & qout , VelocityOut & pout , AccelerationOut & aout , time_type t , time_type dt ) |
| { |
| const value_type one = static_cast< value_type >( 1.0 ); |
| const value_type one_half = static_cast< value_type >( 0.5 ); |
| |
| algebra_stepper_base_type::m_algebra.for_each4( |
| qout , qin , pin , ain , |
| typename operations_type::template scale_sum3< value_type , time_type , time_square_type >( one , one * dt , one_half * dt * dt ) ); |
| |
| typename odeint::unwrap_reference< System >::type & sys = system; |
| |
| sys( qout , pin , aout , t + dt ); |
| |
| algebra_stepper_base_type::m_algebra.for_each4( |
| pout , pin , ain , aout , |
| typename operations_type::template scale_sum3< value_type , time_type , time_type >( one , one_half * dt , one_half * dt ) ); |
| } |
| |
| |
| template< class StateIn > |
| void adjust_size( const StateIn & x ) |
| { |
| if( resize_impl( x ) ) |
| m_first_call = true; |
| } |
| |
| void reset( void ) |
| { |
| m_first_call = true; |
| } |
| |
| |
| /** |
| * \fn velocity_verlet::initialize( const AccelerationIn &qin ) |
| * \brief Initializes the internal state of the stepper. |
| * \param deriv The acceleration of x. The next call of `do_step` expects that the acceleration of `x` passed to `do_step` |
| * has the value of `qin`. |
| */ |
| template< class AccelerationIn > |
| void initialize( const AccelerationIn & ain ) |
| { |
| // alloc a |
| m_resizer.adjust_size( ain , |
| detail::bind( &velocity_verlet::template resize_impl< AccelerationIn > , |
| detail::ref( *this ) , detail::_1 ) ); |
| boost::numeric::odeint::copy( ain , get_current_acc() ); |
| m_first_call = false; |
| } |
| |
| |
| template< class System , class CoorIn , class VelocityIn > |
| void initialize( System system , const CoorIn & qin , const VelocityIn & pin , time_type t ) |
| { |
| m_resizer.adjust_size( qin , |
| detail::bind( &velocity_verlet::template resize_impl< CoorIn > , |
| detail::ref( *this ) , detail::_1 ) ); |
| initialize_acc( system , qin , pin , t ); |
| } |
| |
| bool is_initialized( void ) const |
| { |
| return ! m_first_call; |
| } |
| |
| |
| private: |
| |
| template< class System , class CoorIn , class VelocityIn > |
| void initialize_acc( System system , const CoorIn & qin , const VelocityIn & pin , time_type t ) |
| { |
| typename odeint::unwrap_reference< System >::type & sys = system; |
| sys( qin , pin , get_current_acc() , t ); |
| m_first_call = false; |
| } |
| |
| template< class System , class StateInOut > |
| void do_step_v1( System system , StateInOut & x , time_type t , time_type dt ) |
| { |
| typedef typename odeint::unwrap_reference< StateInOut >::type state_in_type; |
| typedef typename odeint::unwrap_reference< typename state_in_type::first_type >::type coor_in_type; |
| typedef typename odeint::unwrap_reference< typename state_in_type::second_type >::type momentum_in_type; |
| |
| typedef typename boost::remove_reference< coor_in_type >::type xyz_type; |
| state_in_type & statein = x; |
| coor_in_type & qinout = statein.first; |
| momentum_in_type & pinout = statein.second; |
| |
| // alloc a |
| if( m_resizer.adjust_size( qinout , |
| detail::bind( &velocity_verlet::template resize_impl< xyz_type > , |
| detail::ref( *this ) , detail::_1 ) ) |
| || m_first_call ) |
| { |
| initialize_acc( system , qinout , pinout , t ); |
| } |
| |
| // check first |
| do_step( system , qinout , pinout , get_current_acc() , qinout , pinout , get_old_acc() , t , dt ); |
| toggle_current_acc(); |
| } |
| |
| template< class StateIn > |
| bool resize_impl( const StateIn & x ) |
| { |
| bool resized = false; |
| resized |= adjust_size_by_resizeability( m_a1 , x , typename is_resizeable< acceleration_type >::type() ); |
| resized |= adjust_size_by_resizeability( m_a2 , x , typename is_resizeable< acceleration_type >::type() ); |
| return resized; |
| } |
| |
| acceleration_type & get_current_acc( void ) |
| { |
| return m_current_a1 ? m_a1.m_v : m_a2.m_v ; |
| } |
| |
| const acceleration_type & get_current_acc( void ) const |
| { |
| return m_current_a1 ? m_a1.m_v : m_a2.m_v ; |
| } |
| |
| acceleration_type & get_old_acc( void ) |
| { |
| return m_current_a1 ? m_a2.m_v : m_a1.m_v ; |
| } |
| |
| const acceleration_type & get_old_acc( void ) const |
| { |
| return m_current_a1 ? m_a2.m_v : m_a1.m_v ; |
| } |
| |
| void toggle_current_acc( void ) |
| { |
| m_current_a1 = ! m_current_a1; |
| } |
| |
| resizer_type m_resizer; |
| bool m_first_call; |
| wrapped_acceleration_type m_a1 , m_a2; |
| bool m_current_a1; |
| }; |
| |
| /** |
| * \class velocity_verlet |
| * \brief The Velocity-Verlet algorithm. |
| * |
| * <a href="http://en.wikipedia.org/wiki/Verlet_integration" >The Velocity-Verlet algorithm</a> is a method for simulation of molecular dynamics systems. It solves the ODE |
| * a=f(r,v',t) where r are the coordinates, v are the velocities and a are the accelerations, hence v = dr/dt, a=dv/dt. |
| * |
| * \tparam Coor The type representing the coordinates. |
| * \tparam Velocity The type representing the velocities. |
| * \tparam Value The type value type. |
| * \tparam Acceleration The type representing the acceleration. |
| * \tparam Time The time representing the independent variable - the time. |
| * \tparam TimeSq The time representing the square of the time. |
| * \tparam Algebra The algebra. |
| * \tparam Operations The operations type. |
| * \tparam Resizer The resizer policy type. |
| */ |
| |
| |
| /** |
| * \fn velocity_verlet::velocity_verlet( const algebra_type &algebra ) |
| * \brief Constructs the velocity_verlet 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. |
| */ |
| |
| |
| /** |
| * \fn velocity_verlet::do_step( System system , StateInOut &x , time_type t , time_type dt ) |
| * \brief This method performs one step. It transforms the result in-place. |
| * |
| * It can be used like |
| * \code |
| * pair< coordinates , velocities > state; |
| * stepper.do_step( sys , x , t , dt ); |
| * \endcode |
| * |
| * \param system The system function to solve, hence the r.h.s. of the ordinary differential equation. It must fulfill the |
| * Second Order System concept. |
| * \param x The state of the ODE which should be solved. The state is pair of Coor and Velocity. |
| * \param t The value of the time, at which the step should be performed. |
| * \param dt The step size. |
| */ |
| |
| /** |
| * \fn velocity_verlet::do_step( System system , const StateInOut &x , time_type t , time_type dt ) |
| * \brief This method performs one step. It transforms the result in-place. |
| * |
| * It can be used like |
| * \code |
| * pair< coordinates , velocities > state; |
| * stepper.do_step( sys , x , t , dt ); |
| * \endcode |
| * |
| * \param system The system function to solve, hence the r.h.s. of the ordinary differential equation. It must fulfill the |
| * Second Order System concept. |
| * \param x The state of the ODE which should be solved. The state is pair of Coor and Velocity. |
| * \param t The value of the time, at which the step should be performed. |
| * \param dt The step size. |
| */ |
| |
| |
| |
| /** |
| * \fn velocity_verlet::do_step( System system , CoorIn const & qin , VelocityIn const & pin , AccelerationIn const & ain , CoorOut & qout , VelocityOut & pout , AccelerationOut & aout , time_type t , time_type dt ) |
| * \brief This method performs one step. It transforms the result in-place. Additionally to the other methods |
| * the coordinates, velocities and accelerations are passed directly to do_step and they are transformed out-of-place. |
| * |
| * It can be used like |
| * \code |
| * coordinates qin , qout; |
| * velocities pin , pout; |
| * accelerations ain, aout; |
| * stepper.do_step( sys , qin , pin , ain , qout , pout , aout , t , dt ); |
| * \endcode |
| * |
| * \param system The system function to solve, hence the r.h.s. of the ordinary differential equation. It must fulfill the |
| * Second Order System concept. |
| * \param x The state of the ODE which should be solved. The state is pair of Coor and Velocity. |
| * \param t The value of the time, at which the step should be performed. |
| * \param dt The step size. |
| */ |
| |
| |
| /** |
| * \fn void velocity_verlet::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. |
| */ |
| |
| |
| /** |
| * \fn velocity_verlet::reset( void ) |
| * \brief Resets the internal state of this stepper. After calling this method it is safe to use all |
| * `do_step` method without explicitly initializing the stepper. |
| */ |
| |
| |
| |
| /** |
| * \fn velocity_verlet::initialize( System system , const CoorIn &qin , const VelocityIn &pin , time_type t ) |
| * \brief Initializes the internal state of the stepper. |
| * |
| * This method is equivalent to |
| * \code |
| * Acceleration a; |
| * system( qin , pin , a , t ); |
| * stepper.initialize( a ); |
| * \endcode |
| * |
| * \param system The system function for the next calls of `do_step`. |
| * \param qin The current coordinates of the ODE. |
| * \param pin The current velocities of the ODE. |
| * \param t The current time of the ODE. |
| */ |
| |
| |
| /** |
| * \fn velocity_verlet::is_initialized() |
| * \returns Returns if the stepper is initialized. |
| */ |
| |
| |
| |
| |
| } // namespace odeint |
| } // namespace numeric |
| } // namespace boost |
| |
| |
| #endif // BOOST_NUMERIC_ODEINT_STEPPER_VELOCITY_VERLET_HPP_DEFINED |