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/*
[auto_generated]
libs/numeric/odeint/test/euler_stepper.cpp
[begin_description]
This file tests explicit Euler stepper.
[end_description]
Copyright 2011 Mario Mulansky
Copyright 2012 Karsten Ahnert
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE_1_0.txt or
copy at http://www.boost.org/LICENSE_1_0.txt)
*/
#define BOOST_TEST_MODULE odeint_explicit_euler
#include <boost/test/unit_test.hpp>
#include <utility>
#include <iostream>
#include <vector>
#include <boost/numeric/odeint/stepper/euler.hpp>
#include <boost/numeric/odeint/algebra/range_algebra.hpp>
using namespace boost::unit_test;
using namespace boost::numeric::odeint;
// test with own vector implementation
class my_vec : public std::vector< double > {
public:
my_vec() : std::vector< double >()
{ }
my_vec( const my_vec &x ) : std::vector< double >( x )
{ }
my_vec( size_t dim )
: std::vector< double >( dim )
{ }
};
namespace boost {
namespace numeric {
namespace odeint {
template<>
struct is_resizeable< my_vec >
{
//struct type : public boost::true_type { };
typedef boost::true_type type;
const static bool value = type::value;
};
} } }
typedef double value_type;
//typedef std::vector< value_type > state_type;
typedef my_vec state_type;
/* use functors, because functions don't work with msvc 10, I guess this is a bug */
struct sys
{
void operator()( const state_type &x , state_type &dxdt , const value_type t ) const
{
std::cout << "sys start " << dxdt.size() << std::endl;
dxdt[0] = x[0] + 2 * x[1];
dxdt[1] = x[1];
std::cout << "sys done" << std::endl;
}
};
BOOST_AUTO_TEST_SUITE( explicit_euler_test )
BOOST_AUTO_TEST_CASE( test_euler )
{
range_algebra algebra;
euler< state_type > stepper( algebra );
state_type x( 2 );
x[0] = 0.0; x[1] = 1.0;
std::cout << "initialized" << std::endl;
const value_type eps = 1E-12;
const value_type dt = 0.1;
stepper.do_step( sys() , x , 0.0 , dt );
using std::abs;
// compare with analytic solution of above system
BOOST_CHECK_MESSAGE( abs( x[0] - 2.0*1.0*dt ) < eps , x[0] - 2.0*1.0*dt );
BOOST_CHECK_MESSAGE( abs( x[1] - (1.0 + dt) ) < eps , x[1] - (1.0+dt) );
}
BOOST_AUTO_TEST_SUITE_END()
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