65 lines
2.8 KiB
C++
65 lines
2.8 KiB
C++
/*
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* Free FFT and convolution (C++)
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*
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* Copyright (c) 2020 Project Nayuki. (MIT License)
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* https://www.nayuki.io/page/free-small-fft-in-multiple-languages
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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* - The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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* - The Software is provided "as is", without warranty of any kind, express or
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* implied, including but not limited to the warranties of merchantability,
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* fitness for a particular purpose and noninfringement. In no event shall the
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* authors or copyright holders be liable for any claim, damages or other
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* liability, whether in an action of contract, tort or otherwise, arising from,
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* out of or in connection with the Software or the use or other dealings in the
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* Software.
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*/
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#pragma once
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#include <complex>
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#include <vector>
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namespace Fft {
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// swap left/right halves of the vector, similar to matlabs fftshift/ifftshift
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void shift(std::vector<std::complex<double> > &vec, bool inverse);
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/*
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* Computes the discrete Fourier transform (DFT) of the given complex vector, storing the result back into the vector.
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* The vector can have any length. This is a wrapper function. The inverse transform does not perform scaling, so it is not a true inverse.
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*/
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void transform(std::vector<std::complex<double> > &vec, bool inverse);
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/*
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* Computes the discrete Fourier transform (DFT) of the given complex vector, storing the result back into the vector.
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* The vector's length must be a power of 2. Uses the Cooley-Tukey decimation-in-time radix-2 algorithm.
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*/
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void transformRadix2(std::vector<std::complex<double> > &vec, bool inverse);
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/*
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* Computes the discrete Fourier transform (DFT) of the given complex vector, storing the result back into the vector.
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* The vector can have any length. This requires the convolution function, which in turn requires the radix-2 FFT function.
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* Uses Bluestein's chirp z-transform algorithm.
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*/
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void transformBluestein(std::vector<std::complex<double> > &vec, bool inverse);
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/*
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* Computes the circular convolution of the given complex vectors. Each vector's length must be the same.
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*/
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void convolve(
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const std::vector<std::complex<double> > &xvec,
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const std::vector<std::complex<double> > &yvec,
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std::vector<std::complex<double> > &outvec);
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}
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