1 /* Boost libs/numeric/odeint/examples/simple1d.cpp
2
3 Copyright 2012-2013 Mario Mulansky
4 Copyright 2012 Karsten Ahnert
5
6 example for a simple one-dimensional 1st order ODE
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 /* we solve the simple ODE x' = 3/(2t^2) + x/(2t)
22 * with initial condition x(1) = 0.
23 * Analytic solution is x(t) = sqrt(t) - 1/t
24 */
25
rhs(const double x,double & dxdt,const double t)26 void rhs( const double x , double &dxdt , const double t )
27 {
28 dxdt = 3.0/(2.0*t*t) + x/(2.0*t);
29 }
30
write_cout(const double & x,const double t)31 void write_cout( const double &x , const double t )
32 {
33 cout << t << '\t' << x << endl;
34 }
35
36 // state_type = double
37 typedef runge_kutta_dopri5< double > stepper_type;
38
main()39 int main()
40 {
41 double x = 0.0; //initial value x(1) = 0
42 // use dopri5 with stepsize control and allowed errors 10^-12, integrate t=1...10
43 integrate_adaptive( make_controlled( 1E-12 , 1E-12 , stepper_type() ) , rhs , x , 1.0 , 10.0 , 0.1 , write_cout );
44 }
45