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/*
[auto_generated]
libs/numeric/odeint/test/bulirsch_stoer.cpp
[begin_description]
This file tests the Bulirsch-Stoer stepper.
[end_description]
Copyright 2011 Mario Mulansky
Copyright 2012 Karsten Ahnert
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)
*/
// disable checked iterator warning for msvc
#include <boost/config.hpp>
#ifdef BOOST_MSVC
#pragma warning(disable:4996)
#endif
#define BOOST_TEST_MODULE odeint_bulirsch_stoer
#include <utility>
#include <iostream>
#include <boost/array.hpp>
#include <boost/test/unit_test.hpp>
#include <boost/numeric/odeint/stepper/bulirsch_stoer.hpp>
#include <boost/numeric/odeint/stepper/bulirsch_stoer_dense_out.hpp>
#include <boost/numeric/odeint/integrate/integrate_adaptive.hpp>
using namespace boost::unit_test;
using namespace boost::numeric::odeint;
typedef double value_type;
typedef boost::array< value_type , 3 > state_type;
const double sigma = 10.0;
const double R = 28.0;
const double b = 8.0 / 3.0;
struct lorenz
{
template< class State , class Deriv >
void operator()( const State &x , Deriv &dxdt , double t ) const
{
dxdt[0] = sigma * ( x[1] - x[0] );
dxdt[1] = R * x[0] - x[1] - x[0] * x[2];
dxdt[2] = -b * x[2] + x[0] * x[1];
}
};
struct const_system
{
template< class State , class Deriv >
void operator()( const State &x , Deriv &dxdt , double t ) const
{
dxdt[0] = 1.0;
dxdt[1] = 1.0;
dxdt[2] = 1.0;
}
};
struct sin_system
{
template< class State , class Deriv >
void operator()( const State &x , Deriv &dxdt , double t ) const
{
dxdt[0] = sin( x[0] );
dxdt[1] = cos( x[1] );
dxdt[2] = sin( x[2] ) + cos( x[2] );
}
};
BOOST_AUTO_TEST_SUITE( bulirsch_stoer_test )
BOOST_AUTO_TEST_CASE( test_bulirsch_stoer )
{
typedef bulirsch_stoer< state_type > stepper_type;
stepper_type stepper( 1E-9 , 1E-9 , 1.0 , 0.0 );
state_type x;
x[0] = 10.0 ; x[1] = 10.0 ; x[2] = 5.0;
double dt = 0.1;
//stepper.try_step( lorenz() , x , t , dt );
std::cout << "starting integration..." << std::endl;
size_t steps = integrate_adaptive( stepper , lorenz() , x , 0.0 , 10.0 , dt );
std::cout << "required steps: " << steps << std::endl;
bulirsch_stoer_dense_out< state_type > bs_do( 1E-9 , 1E-9 , 1.0 , 0.0 );
x[0] = 10.0 ; x[1] = 10.0 ; x[2] = 5.0;
double t = 0.0;
dt = 1E-1;
bs_do.initialize( x , t , dt );
bs_do.do_step( sin_system() );
std::cout << "one step successful, new time: " << bs_do.current_time() << " (" << t << ")" << std::endl;
x = bs_do.current_state();
std::cout << "x( " << bs_do.current_time() << " ) = [ " << x[0] << " , " << x[1] << " , " << x[2] << " ]" << std::endl;
bs_do.calc_state( bs_do.current_time()/3 , x );
std::cout << "x( " << bs_do.current_time()/3 << " ) = [ " << x[0] << " , " << x[1] << " , " << x[2] << " ]" << std::endl;
std::cout << std::endl << "=======================================================================" << std::endl << std::endl;
x[0] = 10.0 ; x[1] = 10.0 ; x[2] = 5.0;
t = 0.0; dt /= 3;
bs_do.initialize( x , t , dt );
bs_do.do_step( sin_system() );
x = bs_do.current_state();
std::cout << "x( " << bs_do.current_time() << " ) = [ " << x[0] << " , " << x[1] << " , " << x[2] << " ]" << std::endl;
t = dt;
bs_do.initialize( x , t , dt );
bs_do.do_step( sin_system() );
x = bs_do.current_state();
t = 2*dt;
bs_do.initialize( x , t , dt );
bs_do.do_step( sin_system() );
x = bs_do.current_state();
std::cout << "x( " << bs_do.current_time() << " ) = [ " << x[0] << " , " << x[1] << " , " << x[2] << " ]" << std::endl;
}
BOOST_AUTO_TEST_SUITE_END()
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