382 lines
14 KiB
Plaintext
382 lines
14 KiB
Plaintext
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/*
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[auto_generated]
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boost/numeric/odeint/stepper/velocity_verlet.hpp
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[begin_description]
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tba.
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[end_description]
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Copyright 2009-2012 Karsten Ahnert
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Copyright 2009-2012 Mario Mulansky
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE_1_0.txt or
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copy at http://www.boost.org/LICENSE_1_0.txt)
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*/
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#ifndef BOOST_NUMERIC_ODEINT_STEPPER_VELOCITY_VERLET_HPP_DEFINED
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#define BOOST_NUMERIC_ODEINT_STEPPER_VELOCITY_VERLET_HPP_DEFINED
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#include <boost/numeric/odeint/stepper/base/algebra_stepper_base.hpp>
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#include <boost/numeric/odeint/stepper/stepper_categories.hpp>
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#include <boost/numeric/odeint/algebra/algebra_dispatcher.hpp>
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#include <boost/numeric/odeint/algebra/operations_dispatcher.hpp>
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#include <boost/numeric/odeint/util/resizer.hpp>
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#include <boost/numeric/odeint/util/state_wrapper.hpp>
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#include <boost/numeric/odeint/util/unwrap_reference.hpp>
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#include <boost/numeric/odeint/util/bind.hpp>
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#include <boost/numeric/odeint/util/copy.hpp>
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#include <boost/numeric/odeint/util/resizer.hpp>
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// #include <boost/numeric/odeint/util/is_pair.hpp>
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// #include <boost/array.hpp>
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namespace boost {
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namespace numeric {
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namespace odeint {
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template <
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class Coor ,
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class Velocity = Coor ,
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class Value = double ,
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class Acceleration = Coor ,
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class Time = Value ,
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class TimeSq = Time ,
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class Algebra = typename algebra_dispatcher< Coor >::algebra_type ,
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class Operations = typename operations_dispatcher< Coor >::operations_type ,
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class Resizer = initially_resizer
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>
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class velocity_verlet : public algebra_stepper_base< Algebra , Operations >
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{
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public:
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typedef algebra_stepper_base< Algebra , Operations > algebra_stepper_base_type;
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typedef typename algebra_stepper_base_type::algebra_type algebra_type;
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typedef typename algebra_stepper_base_type::operations_type operations_type;
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typedef Coor coor_type;
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typedef Velocity velocity_type;
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typedef Acceleration acceleration_type;
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typedef std::pair< coor_type , velocity_type > state_type;
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typedef std::pair< velocity_type , acceleration_type > deriv_type;
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typedef state_wrapper< acceleration_type > wrapped_acceleration_type;
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typedef Value value_type;
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typedef Time time_type;
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typedef TimeSq time_square_type;
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typedef Resizer resizer_type;
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typedef stepper_tag stepper_category;
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typedef unsigned short order_type;
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static const order_type order_value = 1;
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/**
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* \return Returns the order of the stepper.
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*/
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order_type order( void ) const
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{
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return order_value;
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}
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velocity_verlet( const algebra_type & algebra = algebra_type() )
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: algebra_stepper_base_type( algebra ) , m_first_call( true )
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, m_a1() , m_a2() , m_current_a1( true ) { }
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template< class System , class StateInOut >
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void do_step( System system , StateInOut & x , time_type t , time_type dt )
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{
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do_step_v1( system , x , t , dt );
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}
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template< class System , class StateInOut >
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void do_step( System system , const StateInOut & x , time_type t , time_type dt )
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{
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do_step_v1( system , x , t , dt );
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}
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template< class System , class CoorIn , class VelocityIn , class AccelerationIn ,
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class CoorOut , class VelocityOut , class AccelerationOut >
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void do_step( System system , CoorIn const & qin , VelocityIn const & pin , AccelerationIn const & ain ,
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CoorOut & qout , VelocityOut & pout , AccelerationOut & aout , time_type t , time_type dt )
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{
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const value_type one = static_cast< value_type >( 1.0 );
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const value_type one_half = static_cast< value_type >( 0.5 );
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algebra_stepper_base_type::m_algebra.for_each4(
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qout , qin , pin , ain ,
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typename operations_type::template scale_sum3< value_type , time_type , time_square_type >( one , one * dt , one_half * dt * dt ) );
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typename odeint::unwrap_reference< System >::type & sys = system;
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sys( qout , pin , aout , t + dt );
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algebra_stepper_base_type::m_algebra.for_each4(
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pout , pin , ain , aout ,
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typename operations_type::template scale_sum3< value_type , time_type , time_type >( one , one_half * dt , one_half * dt ) );
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}
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template< class StateIn >
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void adjust_size( const StateIn & x )
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{
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if( resize_impl( x ) )
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m_first_call = true;
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}
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void reset( void )
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{
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m_first_call = true;
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}
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/**
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* \fn velocity_verlet::initialize( const AccelerationIn &qin )
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* \brief Initializes the internal state of the stepper.
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* \param deriv The acceleration of x. The next call of `do_step` expects that the acceleration of `x` passed to `do_step`
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* has the value of `qin`.
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*/
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template< class AccelerationIn >
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void initialize( const AccelerationIn & ain )
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{
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// alloc a
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m_resizer.adjust_size( ain ,
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detail::bind( &velocity_verlet::template resize_impl< AccelerationIn > ,
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detail::ref( *this ) , detail::_1 ) );
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boost::numeric::odeint::copy( ain , get_current_acc() );
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m_first_call = false;
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}
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template< class System , class CoorIn , class VelocityIn >
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void initialize( System system , const CoorIn & qin , const VelocityIn & pin , time_type t )
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{
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m_resizer.adjust_size( qin ,
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detail::bind( &velocity_verlet::template resize_impl< CoorIn > ,
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detail::ref( *this ) , detail::_1 ) );
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initialize_acc( system , qin , pin , t );
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}
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bool is_initialized( void ) const
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{
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return ! m_first_call;
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}
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private:
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template< class System , class CoorIn , class VelocityIn >
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void initialize_acc( System system , const CoorIn & qin , const VelocityIn & pin , time_type t )
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{
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typename odeint::unwrap_reference< System >::type & sys = system;
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sys( qin , pin , get_current_acc() , t );
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m_first_call = false;
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}
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template< class System , class StateInOut >
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void do_step_v1( System system , StateInOut & x , time_type t , time_type dt )
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{
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typedef typename odeint::unwrap_reference< StateInOut >::type state_in_type;
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typedef typename odeint::unwrap_reference< typename state_in_type::first_type >::type coor_in_type;
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typedef typename odeint::unwrap_reference< typename state_in_type::second_type >::type momentum_in_type;
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typedef typename boost::remove_reference< coor_in_type >::type xyz_type;
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state_in_type & statein = x;
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coor_in_type & qinout = statein.first;
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momentum_in_type & pinout = statein.second;
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// alloc a
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if( m_resizer.adjust_size( qinout ,
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detail::bind( &velocity_verlet::template resize_impl< xyz_type > ,
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detail::ref( *this ) , detail::_1 ) )
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|| m_first_call )
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{
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initialize_acc( system , qinout , pinout , t );
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}
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// check first
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do_step( system , qinout , pinout , get_current_acc() , qinout , pinout , get_old_acc() , t , dt );
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toggle_current_acc();
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}
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template< class StateIn >
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bool resize_impl( const StateIn & x )
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{
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bool resized = false;
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resized |= adjust_size_by_resizeability( m_a1 , x , typename is_resizeable< acceleration_type >::type() );
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resized |= adjust_size_by_resizeability( m_a2 , x , typename is_resizeable< acceleration_type >::type() );
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return resized;
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}
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acceleration_type & get_current_acc( void )
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{
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return m_current_a1 ? m_a1.m_v : m_a2.m_v ;
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}
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const acceleration_type & get_current_acc( void ) const
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{
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return m_current_a1 ? m_a1.m_v : m_a2.m_v ;
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}
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acceleration_type & get_old_acc( void )
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{
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return m_current_a1 ? m_a2.m_v : m_a1.m_v ;
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}
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const acceleration_type & get_old_acc( void ) const
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{
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return m_current_a1 ? m_a2.m_v : m_a1.m_v ;
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}
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void toggle_current_acc( void )
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{
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m_current_a1 = ! m_current_a1;
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}
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resizer_type m_resizer;
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bool m_first_call;
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wrapped_acceleration_type m_a1 , m_a2;
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bool m_current_a1;
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};
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/**
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* \class velocity_verlet
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* \brief The Velocity-Verlet algorithm.
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*
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* <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
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* 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.
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*
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* \tparam Coor The type representing the coordinates.
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* \tparam Velocity The type representing the velocities.
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* \tparam Value The type value type.
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* \tparam Acceleration The type representing the acceleration.
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* \tparam Time The time representing the independent variable - the time.
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* \tparam TimeSq The time representing the square of the time.
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* \tparam Algebra The algebra.
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* \tparam Operations The operations type.
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* \tparam Resizer The resizer policy type.
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*/
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/**
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* \fn velocity_verlet::velocity_verlet( const algebra_type &algebra )
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* \brief Constructs the velocity_verlet class. This constructor can be used as a default
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* constructor if the algebra has a default constructor.
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* \param algebra A copy of algebra is made and stored.
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*/
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/**
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* \fn velocity_verlet::do_step( System system , StateInOut &x , time_type t , time_type dt )
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* \brief This method performs one step. It transforms the result in-place.
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*
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* It can be used like
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* \code
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* pair< coordinates , velocities > state;
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* stepper.do_step( sys , x , t , dt );
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* \endcode
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*
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* \param system The system function to solve, hence the r.h.s. of the ordinary differential equation. It must fulfill the
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* Second Order System concept.
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* \param x The state of the ODE which should be solved. The state is pair of Coor and Velocity.
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* \param t The value of the time, at which the step should be performed.
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* \param dt The step size.
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*/
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/**
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* \fn velocity_verlet::do_step( System system , const StateInOut &x , time_type t , time_type dt )
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* \brief This method performs one step. It transforms the result in-place.
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*
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* It can be used like
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* \code
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* pair< coordinates , velocities > state;
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* stepper.do_step( sys , x , t , dt );
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* \endcode
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*
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* \param system The system function to solve, hence the r.h.s. of the ordinary differential equation. It must fulfill the
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* Second Order System concept.
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* \param x The state of the ODE which should be solved. The state is pair of Coor and Velocity.
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* \param t The value of the time, at which the step should be performed.
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* \param dt The step size.
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*/
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/**
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* \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 )
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* \brief This method performs one step. It transforms the result in-place. Additionally to the other methods
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* the coordinates, velocities and accelerations are passed directly to do_step and they are transformed out-of-place.
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*
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* It can be used like
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* \code
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* coordinates qin , qout;
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* velocities pin , pout;
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* accelerations ain, aout;
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* stepper.do_step( sys , qin , pin , ain , qout , pout , aout , t , dt );
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* \endcode
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*
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* \param system The system function to solve, hence the r.h.s. of the ordinary differential equation. It must fulfill the
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* Second Order System concept.
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* \param x The state of the ODE which should be solved. The state is pair of Coor and Velocity.
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* \param t The value of the time, at which the step should be performed.
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* \param dt The step size.
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*/
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/**
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* \fn void velocity_verlet::adjust_size( const StateIn &x )
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* \brief Adjust the size of all temporaries in the stepper manually.
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* \param x A state from which the size of the temporaries to be resized is deduced.
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*/
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/**
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* \fn velocity_verlet::reset( void )
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* \brief Resets the internal state of this stepper. After calling this method it is safe to use all
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* `do_step` method without explicitly initializing the stepper.
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*/
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/**
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* \fn velocity_verlet::initialize( System system , const CoorIn &qin , const VelocityIn &pin , time_type t )
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* \brief Initializes the internal state of the stepper.
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*
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* This method is equivalent to
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* \code
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* Acceleration a;
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* system( qin , pin , a , t );
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* stepper.initialize( a );
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* \endcode
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*
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* \param system The system function for the next calls of `do_step`.
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* \param qin The current coordinates of the ODE.
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* \param pin The current velocities of the ODE.
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* \param t The current time of the ODE.
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*/
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/**
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* \fn velocity_verlet::is_initialized()
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* \returns Returns if the stepper is initialized.
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|
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*/
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} // namespace odeint
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} // namespace numeric
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} // namespace boost
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#endif // BOOST_NUMERIC_ODEINT_STEPPER_VELOCITY_VERLET_HPP_DEFINED
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