kopia lustrzana https://github.com/vsamy/DiFipp
105 wiersze
4.5 KiB
C++
105 wiersze
4.5 KiB
C++
// Copyright (c) 2019, Vincent SAMY
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// All rights reserved.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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// 1. Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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// 2. Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
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// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// The views and conclusions contained in the software and documentation are those
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// of the authors and should not be interpreted as representing official policies,
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// either expressed or implied, of the FreeBSD Project.
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#pragma once
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#include "gsl/gsl_assert.h"
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#include "type_checks.h"
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#include "typedefs.h"
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#include <limits>
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namespace difi {
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/*! \brief Transform an analog signal to a discrete signal and vice versa.
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*
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* \see https://en.wikipedia.org/wiki/Bilinear_transform
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* \tparam T Floating (complex) types.
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*/
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template <typename T>
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struct BilinearTransform {
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using SubType = internal::complex_sub_type_t<T>; /*!< Sub-type of the complex if T is complex, T otherwise */
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static_assert(std::is_floating_point<SubType>::value, "This struct can only accept floating point types (real and complex).");
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/*! \brief Transformation from analog to discrete.
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* \param fs Sampling frequency.
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* \param sPlanePole Analog data.
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* \param[out] zPlanePole Resulting discrete data.
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*/
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static void SToZ(SubType fs, const T& sPlanePole, T& zPlanePole);
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/*! \brief Transformation from analog to discrete.
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* \param fs Sampling frequency.
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* \param sPlanePole Analog signal.
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* \param[out] zPlanePole Resulting discrete signal.
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*/
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static void SToZ(SubType fs, const vectX_t<T>& sPlanePoles, Eigen::Ref<vectX_t<T>>& zPlanePoles); // Can be optimized maybe
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/*! \brief Transformation from discrete to analog.
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* \param fs Sampling frequency.
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* \param zPlanePole Discrete data.
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* \param[out] sPlanePole Resulting analog data.
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*/
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static void ZToS(SubType fs, const T& zPlanePole, T& sPlanePole);
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/*! \brief Transformation from discrete to analog.
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* \param fs Sampling frequency.
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* \param zPlanePole Discrete signal.
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* \param[out] sPlanePole Resulting analog signal.
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*/
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static void ZToS(SubType fs, const vectX_t<T>& zPlanePoles, Eigen::Ref<vectX_t<T>>& sPlanePoles); // Can be optimized maybe
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};
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template <typename T>
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void BilinearTransform<T>::SToZ(SubType fs, const T& sPlanePole, T& zPlanePole)
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{
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Expects(std::abs(2 * fs - sPlanePole) > std::numeric_limits<SubType>::epsilon()); // Divide-by-zero otherwise
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T scalePole = sPlanePole / (2 * fs);
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zPlanePole = (T(1) + scalePole) / (T(1) - scalePole);
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}
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template <typename T>
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void BilinearTransform<T>::SToZ(SubType fs, const vectX_t<T>& sPlanePoles, Eigen::Ref<vectX_t<T>>& zPlanePoles)
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{
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Expects(sPlanePoles.size() == zPlanePoles.size());
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for (Eigen::Index k = 0; k < sPlanePoles.size(); ++k)
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SToZ(fs, sPlanePoles(k), zPlanePoles(k));
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}
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template <typename T>
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void BilinearTransform<T>::ZToS(SubType fs, const T& zPlanePole, T& sPlanePole)
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{
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Expects(std::abs(T(1) + zPlanePole) > std::numeric_limits<SubType>::epsilon()); // Divide-by-zero otherwise
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T invPole = T(1) / zPlanePole;
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sPlanePole = 2 * fs * (T(1) - invPole) / (T(1) + invPole);
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}
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template <typename T>
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void BilinearTransform<T>::ZToS(SubType fs, const vectX_t<T>& zPlanePoles, Eigen::Ref<vectX_t<T>>& sPlanePoles)
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{
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Expects(sPlanePoles.size() == zPlanePoles.size());
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for (Eigen::Index k = 0; k < sPlanePoles.size(); ++k)
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ZToS(fs, zPlanePoles(k), sPlanePoles(k));
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}
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} // namespace difi
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