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/*
* Copyright (C) 2018 Open Source Robotics Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
#ifndef IGNITION_PLUGIN_EXAMPLES_PLUGINS_INTEGRATORS_HH_
#define IGNITION_PLUGIN_EXAMPLES_PLUGINS_INTEGRATORS_HH_
#include <vector>
#include <functional>
namespace ignition
{
namespace plugin
{
namespace examples
{
/// \brief The NumericalIntegrator class defines an interface for plugins
/// that can perform numerical integration on an arbitrary system of
/// ordinary differential equations.
class NumericalIntegrator
{
// Define types for the input and the output of the ODE system.
public: using State = std::vector<double>;
public: using Derivative = std::vector<double>;
public: using Time = double;
public: using TimeStep = double;
public: using SystemODE = std::function<Derivative(Time, const State&)>;
public: using ExactSolution = std::function<State(Time)>;
/// \brief Set the function that defines the system of ordinary
/// differential equations that this integrator should operate on.
/// \param[in] _func A std::function that defines a system of ordinary
/// differential equations.
public: virtual void SetFunction(const SystemODE &_func) = 0;
/// \brief Set the amount of time that this integrator should step each
/// time the Integrate() function is called.
/// \param[in] The desired size of the step, in units of seconds.
/// \return False if the integrator does not support the requested step
/// size.
public: virtual bool SetTimeStep(TimeStep _step) = 0;
/// \brief Get the time step size that the integrator is currently set
/// to use.
/// \return Current time step size.
public: virtual TimeStep GetTimeStep() const = 0;
/// \brief Integrate the input state forward in time, and return it
/// as output.
/// \param[in] _currentTime The current simulation time.
/// \param[in] _state The current state, corresponding to _currentTime
/// \return The result of integrating _state forward in time. The time
/// of the output is equal to _currentTime + GetTimeStep().
public: virtual State Integrate(
Time _currentTime, const State &_state) const = 0;
/// \brief Virtual destructor
public: virtual ~NumericalIntegrator() = default;
};
/// \brief A system of ordinary differential equations that each
/// NumericalIntegrator implementation can be tested against.
struct ODESystem
{
/// \brief Name of this system
public: std::string name;
/// \brief A system of Ordinary Differential Equations to test the
/// numerical integrators.
public: NumericalIntegrator::SystemODE ode;
/// \brief The initial time of the system.
public: NumericalIntegrator::Time initialTime;
/// \brief The initial state of the system.
public: NumericalIntegrator::State initialState;
/// \brief A function that describes the exact solution of the ODE
/// system that is being tested.
public: NumericalIntegrator::ExactSolution exact;
};
/// \brief This interface allows us to create plugins that can provide
/// systems of differential equations to test the numerical integrators
/// against.
class ODESystemFactory
{
/// \brief Create a set of systems of ordinary differential equations.
public: virtual std::vector<ODESystem> CreateSystems() = 0;
/// \brief Virtual destructor
public: virtual ~ODESystemFactory() = default;
};
}
}
}
#endif
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