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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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