ceph/src/boost/libs/numeric/odeint/examples/gmpxx/lorenz_gmpxx.cpp

   1 /*
   2  * lorenz_gmpxx.cpp
   3  *
   4  * This example demonstrates how odeint can be used with arbitrary precision types.
   5  *
   6  * Copyright 2011-2012 Karsten Ahnert
   7  * Copyright 2011-2012 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 #include <boost/array.hpp>
  18
  19 #include <gmpxx.h>
  20
  21 #include <boost/numeric/odeint.hpp>
  22
  23 using namespace std;
  24 using namespace boost::numeric::odeint;
  25
  26 //[ gmpxx_lorenz
  27 typedef mpf_class value_type;
  28 typedef boost::array< value_type , 3 > state_type;
  29
  30 struct lorenz
  31 {
  32     void operator()( const state_type &x , state_type &dxdt , value_type t ) const
  33     {
  34         const value_type sigma( 10.0 );
  35         const value_type R( 28.0 );
  36         const value_type b( value_type( 8.0 ) / value_type( 3.0 ) );
  37
  38         dxdt[0] = sigma * ( x[1] - x[0] );
  39         dxdt[1] = R * x[0] - x[1] - x[0] * x[2];
  40         dxdt[2] = -b * x[2] + x[0] * x[1];
  41     }
  42 };
  43 //]
  44
  45
  46
  47
  48 struct streaming_observer
  49 {
  50     std::ostream& m_out;
  51
  52     streaming_observer( std::ostream &out ) : m_out( out ) { }
  53
  54     template< class State , class Time >
  55     void operator()( const State &x , Time t ) const
  56     {
  57         m_out << t;
  58         for( size_t i=0 ; i<x.size() ; ++i ) m_out << "\t" << x[i] ;
  59         m_out << "\n";
  60     }
  61 };
  62
  63
  64
  65
  66
  67
  68 int main( int argc , char **argv )
  69 {
  70     //[ gmpxx_integration
  71     const int precision = 1024;
  72     mpf_set_default_prec( precision );
  73
  74     state_type x = {{ value_type( 10.0 ) , value_type( 10.0 ) , value_type( 10.0 ) }};
  75
  76     cout.precision( 1000 );
  77     integrate_const( runge_kutta4< state_type , value_type >() ,
  78             lorenz() , x , value_type( 0.0 ) , value_type( 10.0 ) , value_type( value_type( 1.0 ) / value_type( 10.0 ) ) ,
  79             streaming_observer( cout ) );
  80     //]
  81
  82     return 0;
  83 }