64 lines
1.8 KiB
C++
64 lines
1.8 KiB
C++
/*
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* odeint_rk4_array
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*
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* Copyright 2011 Mario Mulansky
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* Copyright 2012 Karsten Ahnert
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*
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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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#include <iostream>
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#include <boost/timer.hpp>
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#include <boost/array.hpp>
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#include <boost/numeric/odeint/stepper/runge_kutta4_classic.hpp>
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#include <boost/numeric/odeint/stepper/runge_kutta4.hpp>
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#include <boost/numeric/odeint/algebra/array_algebra.hpp>
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#include "lorenz.hpp"
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typedef boost::timer timer_type;
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typedef boost::array< double , 3 > state_type;
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using namespace boost::numeric::odeint;
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//typedef boost::numeric::odeint::runge_kutta4_classic< state_type > rk4_odeint_type;
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// use the never resizer explicitely for optimal performance with gcc,
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// for the intel compiler this doesnt matter and the above definition
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// gives the same performance
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typedef runge_kutta4_classic< state_type , double , state_type , double ,
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array_algebra, default_operations, never_resizer > rk4_odeint_type;
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const int loops = 21;
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const int num_of_steps = 20000000;
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const double dt = 1E-10;
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int main()
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{
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double min_time = 1E6; // something big
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rk4_odeint_type stepper;
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std::clog.precision(16);
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std::cout.precision(16);
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for( int n=0; n<loops; n++ )
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{
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state_type x = {{ 8.5, 3.1, 1.2 }};
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double t = 0.0;
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timer_type timer;
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for( size_t i = 0 ; i < num_of_steps ; ++i )
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{
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stepper.do_step( lorenz(), x, t, dt );
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t += dt;
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}
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min_time = std::min( timer.elapsed() , min_time );
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std::clog << timer.elapsed() << '\t' << x[0] << std::endl;
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}
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std::cout << "Minimal Runtime: " << min_time << std::endl;
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}
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