1 /*
2 * stuart_landau.cpp
3 *
4 * This example demonstrates how one can use odeint can be used with state types consisting of complex variables.
5 *
6 * Copyright 2011-2012 Karsten Ahnert
7 * Copyright 2011-2013 Mario Mulansky
8 * Distributed under the Boost Software License, Version 1.0. (See
9 * accompanying file LICENSE_1_0.txt or copy at
10 * http://www.boost.org/LICENSE_1_0.txt)
11 */
12
13 #include <iostream>
14 #include <complex>
15 #include <boost/array.hpp>
16
17 #include <boost/numeric/odeint.hpp>
18
19 using namespace std;
20 using namespace boost::numeric::odeint;
21
22 //[ stuart_landau_system_function
23 typedef complex< double > state_type;
24
25 struct stuart_landau
26 {
27 double m_eta;
28 double m_alpha;
29
stuart_landaustuart_landau30 stuart_landau( double eta = 1.0 , double alpha = 1.0 )
31 : m_eta( eta ) , m_alpha( alpha ) { }
32
operator ()stuart_landau33 void operator()( const state_type &x , state_type &dxdt , double t ) const
34 {
35 const complex< double > I( 0.0 , 1.0 );
36 dxdt = ( 1.0 + m_eta * I ) * x - ( 1.0 + m_alpha * I ) * norm( x ) * x;
37 }
38 };
39 //]
40
41
42 /*
43 //[ stuart_landau_system_function_alternative
44 double eta = 1.0;
45 double alpha = 1.0;
46
47 void stuart_landau( const state_type &x , state_type &dxdt , double t )
48 {
49 const complex< double > I( 0.0 , 1.0 );
50 dxdt = ( 1.0 + m_eta * I ) * x - ( 1.0 + m_alpha * I ) * norm( x ) * x;
51 }
52 //]
53 */
54
55
56 struct streaming_observer
57 {
58 std::ostream& m_out;
59
streaming_observerstreaming_observer60 streaming_observer( std::ostream &out ) : m_out( out ) { }
61
62 template< class State >
operator ()streaming_observer63 void operator()( const State &x , double t ) const
64 {
65 m_out << t;
66 m_out << "\t" << x.real() << "\t" << x.imag() ;
67 m_out << "\n";
68 }
69 };
70
71
72
73
main(int argc,char ** argv)74 int main( int argc , char **argv )
75 {
76 //[ stuart_landau_integration
77 state_type x = complex< double >( 1.0 , 0.0 );
78
79 const double dt = 0.1;
80
81 typedef runge_kutta4< state_type > stepper_type;
82
83 integrate_const( stepper_type() , stuart_landau( 2.0 , 1.0 ) , x , 0.0 , 10.0 , dt , streaming_observer( cout ) );
84 //]
85
86 return 0;
87 }
88