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#ifndef ALCOMPLEX_H
#define ALCOMPLEX_H
#include <complex>
#include <type_traits>
#include "alspan.h"
/**
* Iterative implementation of 2-radix FFT (In-place algorithm). Sign = -1 is
* FFT and 1 is inverse FFT. Applies the Discrete Fourier Transform (DFT) to
* the data supplied in the buffer, which MUST BE power of two.
*/
template<typename Real>
std::enable_if_t<std::is_floating_point<Real>::value>
complex_fft(const al::span<std::complex<Real>> buffer, const al::type_identity_t<Real> sign);
/**
* Calculate the frequency-domain response of the time-domain signal in the
* provided buffer, which MUST BE power of two.
*/
template<typename Real, size_t N>
std::enable_if_t<std::is_floating_point<Real>::value>
forward_fft(const al::span<std::complex<Real>,N> buffer)
{ complex_fft(buffer.subspan(0), -1); }
/**
* Calculate the time-domain signal of the frequency-domain response in the
* provided buffer, which MUST BE power of two.
*/
template<typename Real, size_t N>
std::enable_if_t<std::is_floating_point<Real>::value>
inverse_fft(const al::span<std::complex<Real>,N> buffer)
{ complex_fft(buffer.subspan(0), 1); }
/**
* Calculate the complex helical sequence (discrete-time analytical signal) of
* the given input using the discrete Hilbert transform (In-place algorithm).
* Fills the buffer with the discrete-time analytical signal stored in the
* buffer. The buffer is an array of complex numbers and MUST BE power of two,
* and the imaginary components should be cleared to 0.
*/
void complex_hilbert(const al::span<std::complex<double>> buffer);
#endif /* ALCOMPLEX_H */
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