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45 lines
1.1 KiB
C++
45 lines
1.1 KiB
C++
/* Boost libs/numeric/odeint/examples/simple1d.cpp
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Copyright 2012-2013 Mario Mulansky
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Copyright 2012 Karsten Ahnert
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example for a simple one-dimensional 1st order ODE
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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/numeric/odeint.hpp>
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using namespace std;
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using namespace boost::numeric::odeint;
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/* we solve the simple ODE x' = 3/(2t^2) + x/(2t)
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* with initial condition x(1) = 0.
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* Analytic solution is x(t) = sqrt(t) - 1/t
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*/
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void rhs( const double x , double &dxdt , const double t )
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{
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dxdt = 3.0/(2.0*t*t) + x/(2.0*t);
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}
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void write_cout( const double &x , const double t )
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{
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cout << t << '\t' << x << endl;
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}
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// state_type = double
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typedef runge_kutta_dopri5< double > stepper_type;
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int main()
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{
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double x = 0.0; //initial value x(1) = 0
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// use dopri5 with stepsize control and allowed errors 10^-12, integrate t=1...10
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integrate_adaptive( make_controlled( 1E-12 , 1E-12 , stepper_type() ) , rhs , x , 1.0 , 10.0 , 0.1 , write_cout );
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}
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