1 /*
2 * lorenz_mp.cpp
3 *
4 * This example demonstrates how odeint can be used with boost.multiprecision.
5 *
6 * Copyright 2011-2012 Karsten Ahnert
7 * Copyright 2013 Mario Mulansky
8 *
9 * Distributed under the Boost Software License, Version 1.0.
10 * (See accompanying file LICENSE_1_0.txt or
11 * copy at http://www.boost.org/LICENSE_1_0.txt)
12 */
13
14
15
16 #include <iostream>
17
18 //[ mp_lorenz_defs
19 #include <boost/numeric/odeint.hpp>
20 #include <boost/multiprecision/cpp_dec_float.hpp>
21
22 using namespace std;
23 using namespace boost::numeric::odeint;
24
25 typedef boost::multiprecision::cpp_dec_float_50 value_type;
26
27 typedef boost::array< value_type , 3 > state_type;
28 //]
29
30 //[ mp_lorenz_rhs
31 struct lorenz
32 {
operator ()lorenz33 void operator()( const state_type &x , state_type &dxdt , value_type t ) const
34 {
35 const value_type sigma( 10 );
36 const value_type R( 28 );
37 const value_type b( value_type( 8 ) / value_type( 3 ) );
38
39 dxdt[0] = sigma * ( x[1] - x[0] );
40 dxdt[1] = R * x[0] - x[1] - x[0] * x[2];
41 dxdt[2] = -b * x[2] + x[0] * x[1];
42 }
43 };
44 //]
45
46
47
48
49 struct streaming_observer
50 {
51 std::ostream& m_out;
52
streaming_observerstreaming_observer53 streaming_observer( std::ostream &out ) : m_out( out ) { }
54
55 template< class State , class Time >
operator ()streaming_observer56 void operator()( const State &x , Time t ) const
57 {
58 m_out << t;
59 for( size_t i=0 ; i<x.size() ; ++i ) m_out << "\t" << x[i] ;
60 m_out << "\n";
61 }
62 };
63
64
65
66
67
68
main(int argc,char ** argv)69 int main( int argc , char **argv )
70 {
71 //[ mp_lorenz_int
72 state_type x = {{ value_type( 10.0 ) , value_type( 10.0 ) , value_type( 10.0 ) }};
73
74 cout.precision( 50 );
75 integrate_const( runge_kutta4< state_type , value_type >() ,
76 lorenz() , x , value_type( 0.0 ) , value_type( 10.0 ) , value_type( value_type( 1.0 ) / value_type( 10.0 ) ) ,
77 streaming_observer( cout ) );
78 //]
79
80 return 0;
81 }
82