euler.h

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/* 
* Copyright (C) 2020-2026 MEmilio
*
* Authors: Martin J. Kuehn, Daniel Abele
*
* Contact: Martin J. Kuehn <Martin.Kuehn@DLR.de>
*
* 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 MIO_MATH_EULER_H
#define MIO_MATH_EULER_H
 
#include "memilio/math/integrator.h"
 
namespace mio
{
 
template <typename FP>
class EulerIntegratorCore : public OdeIntegratorCore<FP>
{
public:
    EulerIntegratorCore()
        : OdeIntegratorCore<FP>(FP{}, FP{})
    {
    }
 
    std::unique_ptr<OdeIntegratorCore<FP>> clone() const override
    {
        return std::make_unique<EulerIntegratorCore>(*this);
    }
 
    bool step(const DerivFunction<FP>& f, Eigen::Ref<const Eigen::VectorX<FP>> yt, FP& t, FP& dt,
              Eigen::Ref<Eigen::VectorX<FP>> ytp1) const override
    {
        // we are misusing the next step y as temporary space to store the derivative
        f(yt, t, ytp1);
        ytp1 = yt + dt * ytp1;
        t += dt;
        return true;
    }
};
 
} // namespace mio
 
#endif // MIO_MATH_EULER_H