ceph/src/boost/libs/numeric/odeint/test/euler_stepper.cpp

   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
  38     my_vec() : std::vector< double >()
  39         { }
  40
  41     my_vec( const my_vec &x ) : std::vector< double >( x )
  42         { }
  43
  44
  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 {
  71     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
  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()