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boost::numeric::odeint::euler — An implementation of the Euler method.
// In header: <boost/numeric/odeint/stepper/euler.hpp> template<typename State, typename Value = double, typename Deriv = State, typename Time = Value, typename Algebra = typename algebra_dispatcher< State >::algebra_type, typename Operations = typename operations_dispatcher< State >::operations_type, typename Resizer = initially_resizer> class euler : public explicit_stepper_base { public: // types typedef explicit_stepper_base< euler< ... >,... > stepper_base_type; typedef stepper_base_type::state_type state_type; typedef stepper_base_type::value_type value_type; typedef stepper_base_type::deriv_type deriv_type; typedef stepper_base_type::time_type time_type; typedef stepper_base_type::algebra_type algebra_type; typedef stepper_base_type::operations_type operations_type; typedef stepper_base_type::resizer_type resizer_type; // construct/copy/destruct euler(const algebra_type & = algebra_type()); // public member functions template<typename System, typename StateIn, typename DerivIn, typename StateOut> void do_step_impl(System, const StateIn &, const DerivIn &, time_type, StateOut &, time_type); template<typename StateOut, typename StateIn1, typename StateIn2> void calc_state(StateOut &, time_type, const StateIn1 &, time_type, const StateIn2 &, time_type) const; template<typename StateType> void adjust_size(const StateType &); };
The Euler method is a very simply solver for ordinary differential equations. This method should not be used for real applications. It is only useful for demonstration purposes. Step size control is not provided but trivial continuous output is available.
This class derives from explicit_stepper_base and inherits its interface via CRTP (current recurring template pattern), see explicit_stepper_base
typename State
The state type.
typename Value = double
The value type.
typename Deriv = State
The type representing the time derivative of the state.
typename Time = Value
The time representing the independent variable  the time.
typename Algebra = typename algebra_dispatcher< State >::algebra_type
The algebra type.
typename Operations = typename operations_dispatcher< State >::operations_type
The operations type.
typename Resizer = initially_resizer
The resizer policy type.
euler
public member functionstemplate<typename System, typename StateIn, typename DerivIn, typename StateOut> void do_step_impl(System system, const StateIn & in, const DerivIn & dxdt, time_type t, StateOut & out, time_type dt);This method performs one step. The derivative
dxdt
of in
at the time t
is passed to the method. The result is updated out of place, hence the input is in in
and the output in out
. Access to this step functionality is provided by explicit_stepper_base and do_step_impl
should not be called directly.
Parameters: 

template<typename StateOut, typename StateIn1, typename StateIn2> void calc_state(StateOut & x, time_type t, const StateIn1 & old_state, time_type t_old, const StateIn2 & current_state, time_type t_new) const;This method is used for continuous output and it calculates the state
x
at a time t
from the knowledge of two states old_state
and current_state
at time points t_old
and t_new
. template<typename StateType> void adjust_size(const StateType & x);Adjust the size of all temporaries in the stepper manually.
Parameters: 
