FFpFourier.H

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// SPDX-FileCopyrightText: 2023 SAP SE
//
// SPDX-License-Identifier: Apache-2.0
//
// This file is part of FEDEM - https://openfedem.org
 
#ifndef FFP_FOURIER_H
#define FFP_FOURIER_H
 
#include <vector>
 
 
class FFpFourier
{
public:
  static bool FFT (const std::vector<double>& xRe,
                   const std::vector<double>& xIm,
           std::vector<double>& yRe, std::vector<double>& yIm);
 
  static int getMaxPrimeFactor ();
 
private:
  static bool transTableSetup (int* sofar, int* actual, int* remain,
                   int& nFact, int nPoints);
 
  static void factorize (int n, int& nFact, int* fact);
 
  static void permute (int nFact, int* fact, int* remain,
               const std::vector<double>& xRe,
               const std::vector<double>& xIm,
               std::vector<double>& yRe,
               std::vector<double>& yIm);
 
  static void twiddleTransf (int sofarRadix, int radix, int remainRadix,
                 std::vector<double>& yRe,
                 std::vector<double>& yIm);
  static void initTrig (int radix);
  static void fft_4 (double* aRe, double* aIm);
  static void fft_5 (double* aRe, double* aIm);
  static void fft_8 ();
  static void fft_10 ();
  static void fft_odd (int radix);
};
 
#endif