Boost C++ Libraries

boost/numeric/odeint/integrate/detail/integrate_n_steps.hpp

/*
 [auto_generated]
 boost/numeric/odeint/integrate/detail/integrate_n_steps.hpp

 [begin_description]
 integrate steps implementation
 [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_INTEGRATE_DETAIL_INTEGRATE_N_STEPS_HPP_INCLUDED
#define BOOST_NUMERIC_ODEINT_INTEGRATE_DETAIL_INTEGRATE_N_STEPS_HPP_INCLUDED

#include <boost/numeric/odeint/util/unwrap_reference.hpp>
#include <boost/numeric/odeint/stepper/stepper_categories.hpp>
#include <boost/numeric/odeint/integrate/detail/integrate_adaptive.hpp>
#include <boost/numeric/odeint/util/unit_helper.hpp>

#include <boost/numeric/odeint/util/detail/less_with_sign.hpp>

namespace boost {
namespace numeric {
namespace odeint {
namespace detail {

// forward declaration
template< class Stepper , class System , class State , class Time , class Observer >
size_t integrate_adaptive(
        Stepper stepper , System system , State &start_state ,
        Time &start_time , Time end_time , Time &dt ,
        Observer observer , controlled_stepper_tag
);


/* basic version */
template< class Stepper , class System , class State , class Time , class Observer>
Time integrate_n_steps(
        Stepper stepper , System system , State &start_state ,
        Time start_time , Time dt , size_t num_of_steps ,
        Observer observer , stepper_tag )
{
    typename odeint::unwrap_reference< Observer >::type &obs = observer;

    Time time = start_time;

    for( size_t step = 0; step < num_of_steps ; ++step )
    {
        obs( start_state , time );
        stepper.do_step( system , start_state , time , dt );
        // direct computation of the time avoids error propagation happening when using time += dt
        // we need clumsy type analysis to get boost units working here
        time = start_time + static_cast< typename unit_value_type<Time>::type >( step+1 ) * dt;
    }
    obs( start_state , time );

    return time;
}


/* controlled version */
template< class Stepper , class System , class State , class Time , class Observer>
Time integrate_n_steps(
        Stepper stepper , System system , State &start_state ,
        Time start_time , Time dt , size_t num_of_steps ,
        Observer observer , controlled_stepper_tag )
{
    typename odeint::unwrap_reference< Observer >::type &obs = observer;

    Time time = start_time;
    Time time_step = dt;

    for( size_t step = 0; step < num_of_steps ; ++step )
    {
        obs( start_state , time );
        detail::integrate_adaptive( stepper , system , start_state , time , time+time_step , dt ,
                null_observer() , controlled_stepper_tag() );
        // direct computation of the time avoids error propagation happening when using time += dt
        // we need clumsy type analysis to get boost units working here
        time = start_time + static_cast< typename unit_value_type<Time>::type >(step+1) * time_step;
    }
    obs( start_state , time );

    return time;
}


/* dense output version */
template< class Stepper , class System , class State , class Time , class Observer>
Time integrate_n_steps(
        Stepper stepper , System system , State &start_state ,
        Time start_time , Time dt , size_t num_of_steps ,
        Observer observer , dense_output_stepper_tag )
{
    typename odeint::unwrap_reference< Observer >::type &obs = observer;

    Time time = start_time;
    const Time end_time = start_time + static_cast< typename unit_value_type<Time>::type >(num_of_steps) * dt;

    stepper.initialize( start_state , time , dt );

    size_t step = 0;

    while( step < num_of_steps )
    {
        while( less_with_sign( time , stepper.current_time() , stepper.current_time_step() ) )
        {
            stepper.calc_state( time , start_state );
            obs( start_state , time );
            ++step;
            // direct computation of the time avoids error propagation happening when using time += dt
            // we need clumsy type analysis to get boost units working here
            time = start_time + static_cast< typename unit_value_type<Time>::type >(step) * dt;
        }

        // we have not reached the end, do another real step
        if( less_with_sign( stepper.current_time()+stepper.current_time_step() ,
                            end_time ,
                            stepper.current_time_step() ) )
        {
            stepper.do_step( system );
        }
        else if( less_with_sign( stepper.current_time() , end_time , stepper.current_time_step() ) )
        { // do the last step ending exactly on the end point
            stepper.initialize( stepper.current_state() , stepper.current_time() , end_time - stepper.current_time() );
            stepper.do_step( system );
        }
    }

    while( stepper.current_time() < end_time )
    {
        if( less_with_sign( end_time ,
                            stepper.current_time()+stepper.current_time_step() ,
                            stepper.current_time_step() ) )
            stepper.initialize( stepper.current_state() , stepper.current_time() , end_time - stepper.current_time() );
        stepper.do_step( system );
    }

    // observation at end point, only if we ended exactly on the end-point (or above due to finite precision)
    obs( stepper.current_state() , end_time );

    return time;
}


}
}
}
}

#endif /* BOOST_NUMERIC_ODEINT_INTEGRATE_DETAIL_INTEGRATE_N_STEPS_HPP_INCLUDED */