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- /*
- * odeint_rk4_array
- *
- * 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)
- */
- #include <iostream>
- #include <boost/timer.hpp>
- #include <boost/array.hpp>
- #include <boost/numeric/odeint/stepper/runge_kutta4_classic.hpp>
- #include <boost/numeric/odeint/stepper/runge_kutta4.hpp>
- #include <boost/numeric/odeint/algebra/array_algebra.hpp>
- #include "lorenz.hpp"
- typedef boost::timer timer_type;
- typedef boost::array< double , 3 > state_type;
- using namespace boost::numeric::odeint;
- //typedef boost::numeric::odeint::runge_kutta4_classic< state_type > rk4_odeint_type;
- // use the never resizer explicitely for optimal performance with gcc,
- // for the intel compiler this doesnt matter and the above definition
- // gives the same performance
- typedef runge_kutta4_classic< state_type , double , state_type , double ,
- array_algebra, default_operations, never_resizer > rk4_odeint_type;
- const int loops = 21;
- const int num_of_steps = 20000000;
- const double dt = 1E-10;
- int main()
- {
- double min_time = 1E6; // something big
- rk4_odeint_type stepper;
- std::clog.precision(16);
- std::cout.precision(16);
- for( int n=0; n<loops; n++ )
- {
- state_type x = {{ 8.5, 3.1, 1.2 }};
- double t = 0.0;
- timer_type timer;
- for( size_t i = 0 ; i < num_of_steps ; ++i )
- {
- stepper.do_step( lorenz(), x, t, dt );
- t += dt;
- }
- min_time = std::min( timer.elapsed() , min_time );
- std::clog << timer.elapsed() << '\t' << x[0] << std::endl;
- }
- std::cout << "Minimal Runtime: " << min_time << std::endl;
- }
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