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
rhs(const double x,double & dxdt,const double t)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
write_cout(const double & x,const double t)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
main()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 }
55