1 /*
2 [auto_generated]
3 libs/numeric/odeint/test/euler_stepper.cpp
4
5 [begin_description]
6 This file tests explicit Euler stepper.
7 [end_description]
8
9 Copyright 2011 Mario Mulansky
10 Copyright 2012 Karsten Ahnert
11
12 Distributed under the Boost Software License, Version 1.0.
13 (See accompanying file LICENSE_1_0.txt or
14 copy at http://www.boost.org/LICENSE_1_0.txt)
15 */
16
17
18 #define BOOST_TEST_MODULE odeint_explicit_euler
19
20 #include <boost/test/unit_test.hpp>
21
22 #include <utility>
23 #include <iostream>
24 #include <vector>
25
26 #include <boost/numeric/odeint/stepper/euler.hpp>
27 #include <boost/numeric/odeint/algebra/range_algebra.hpp>
28
29 using namespace boost::unit_test;
30 using namespace boost::numeric::odeint;
31
32 // test with own vector implementation
33
34 class my_vec : public std::vector< double > {
35
36 public:
37
my_vec()38 my_vec() : std::vector< double >()
39 { }
40
my_vec(const my_vec & x)41 my_vec( const my_vec &x ) : std::vector< double >( x )
42 { }
43
44
my_vec(size_t dim)45 my_vec( size_t dim )
46 : std::vector< double >( dim )
47 { }
48
49 };
50
51 namespace boost {
52 namespace numeric {
53 namespace odeint {
54
55 template<>
56 struct is_resizeable< my_vec >
57 {
58 //struct type : public boost::true_type { };
59 typedef boost::true_type type;
60 const static bool value = type::value;
61 };
62 } } }
63
64 typedef double value_type;
65 //typedef std::vector< value_type > state_type;
66 typedef my_vec state_type;
67
68 /* use functors, because functions don't work with msvc 10, I guess this is a bug */
69 struct sys
70 {
operator ()sys71 void operator()( const state_type &x , state_type &dxdt , const value_type t ) const
72 {
73 std::cout << "sys start " << dxdt.size() << std::endl;
74 dxdt[0] = x[0] + 2 * x[1];
75 dxdt[1] = x[1];
76 std::cout << "sys done" << std::endl;
77 }
78 };
79
80
81 BOOST_AUTO_TEST_SUITE( explicit_euler_test )
82
BOOST_AUTO_TEST_CASE(test_euler)83 BOOST_AUTO_TEST_CASE( test_euler )
84 {
85 range_algebra algebra;
86 euler< state_type > stepper( algebra );
87 state_type x( 2 );
88 x[0] = 0.0; x[1] = 1.0;
89
90 std::cout << "initialized" << std::endl;
91
92 const value_type eps = 1E-12;
93 const value_type dt = 0.1;
94
95 stepper.do_step( sys() , x , 0.0 , dt );
96
97 using std::abs;
98
99 // compare with analytic solution of above system
100 BOOST_CHECK_MESSAGE( abs( x[0] - 2.0*1.0*dt ) < eps , x[0] - 2.0*1.0*dt );
101 BOOST_CHECK_MESSAGE( abs( x[1] - (1.0 + dt) ) < eps , x[1] - (1.0+dt) );
102
103 }
104
105 BOOST_AUTO_TEST_SUITE_END()
106