ceph/src/boost/libs/numeric/odeint/examples/integrate_times.cpp

   1 /* Boost libs/numeric/odeint/examples/integrate_times.cpp
   2
   3  Copyright 2009-2014 Karsten Ahnert
   4  Copyright 2009-2014 Mario Mulansky
   5
   6  example for the use of integrate_times
   7
   8  Distributed under the Boost Software License, Version 1.0.
   9 (See accompanying file LICENSE_1_0.txt or
  10  copy at http://www.boost.org/LICENSE_1_0.txt)
  11  */
  12
  13
  14 #include <iostream>
  15 #include <boost/numeric/odeint.hpp>
  16
  17 using namespace std;
  18 using namespace boost::numeric::odeint;
  19
  20
  21 /*
  22  * simple 1D ODE
  23  */
  24
  25 void rhs( const double x , double &dxdt , const double t )
  26 {
  27     dxdt = 3.0/(2.0*t*t) + x/(2.0*t);
  28 }
  29
  30 void write_cout( const double &x , const double t )
  31 {
  32     cout << t << '\t' << x << endl;
  33 }
  34
  35 // state_type = double
  36 typedef runge_kutta_dopri5< double > stepper_type;
  37
  38 const double dt = 0.1;
  39
  40 int main()
  41 {
  42     // create a vector with observation time points
  43     std::vector<double> times( 91 );
  44     for( size_t i=0 ; i<times.size() ; ++i )
  45         times[i] = 1.0 + dt*i;
  46
  47     double x = 0.0; //initial value x(1) = 0
  48     // we can provide the observation time as a boost range (i.e. the vector)
  49     integrate_times( make_controlled( 1E-12 , 1E-12 , stepper_type() ) , rhs ,
  50                      x , times , dt , write_cout );
  51     // or as two iterators
  52     //integrate_times( make_controlled( 1E-12 , 1E-12 , stepper_type() ) , rhs ,
  53     //                   x , times.begin() , times.end() , dt , write_cout );
  54 }