96 lines
2.4 KiB
C++
96 lines
2.4 KiB
C++
/*
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* van_der_pol_stiff.cpp
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*
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* Created on: Dec 12, 2011
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*
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* Copyright 2012 Karsten Ahnert
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* Copyright 2012-2013 Rajeev Singh
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* Copyright 2012-2013 Mario Mulansky
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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 <fstream>
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#include <utility>
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#include <boost/numeric/odeint.hpp>
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#include <boost/phoenix/core.hpp>
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#include <boost/phoenix/operator.hpp>
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using namespace std;
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using namespace boost::numeric::odeint;
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namespace phoenix = boost::phoenix;
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const double mu = 1000.0;
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typedef boost::numeric::ublas::vector< double > vector_type;
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typedef boost::numeric::ublas::matrix< double > matrix_type;
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struct vdp_stiff
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{
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void operator()( const vector_type &x , vector_type &dxdt , double t )
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{
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dxdt[0] = x[1];
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dxdt[1] = -x[0] - mu * x[1] * (x[0]*x[0]-1.0);
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}
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};
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struct vdp_stiff_jacobi
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{
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void operator()( const vector_type &x , matrix_type &J , const double &t , vector_type &dfdt )
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{
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J(0, 0) = 0.0;
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J(0, 1) = 1.0;
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J(1, 0) = -1.0 - 2.0*mu * x[0] * x[1];
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J(1, 1) = -mu * ( x[0] * x[0] - 1.0);
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dfdt[0] = 0.0;
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dfdt[1] = 0.0;
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}
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};
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int main( int argc , char **argv )
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{
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//[ integrate_stiff_system
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vector_type x( 2 );
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/* initialize random seed: */
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srand ( time(NULL) );
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// initial conditions
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for (int i=0; i<2; i++)
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x[i] = 1.0; //(1.0 * rand()) / RAND_MAX;
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size_t num_of_steps = integrate_const( make_dense_output< rosenbrock4< double > >( 1.0e-6 , 1.0e-6 ) ,
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make_pair( vdp_stiff() , vdp_stiff_jacobi() ) ,
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x , 0.0 , 1000.0 , 1.0
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, cout << phoenix::arg_names::arg2 << " " << phoenix::arg_names::arg1[0] << " " << phoenix::arg_names::arg1[1] << "\n"
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);
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//]
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clog << num_of_steps << endl;
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//[ integrate_stiff_system_alternative
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vector_type x2( 2 );
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// initial conditions
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for (int i=0; i<2; i++)
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x2[i] = 1.0; //(1.0 * rand()) / RAND_MAX;
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//size_t num_of_steps2 = integrate_const( make_dense_output< runge_kutta_dopri5< vector_type > >( 1.0e-6 , 1.0e-6 ) ,
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// vdp_stiff() , x2 , 0.0 , 1000.0 , 1.0
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// , cout << phoenix::arg_names::arg2 << " " << phoenix::arg_names::arg1[0] << " " << phoenix::arg_names::arg1[1] << "\n"
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// );
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//]
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//clog << num_of_steps2 << endl;
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return 0;
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}
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