common/alcomplex.h

   1 #ifndef ALCOMPLEX_H
   2 #define ALCOMPLEX_H
   3
   4 #include <complex>
   5
   6 #include "alspan.h"
   7
   8 /**
   9  * Iterative implementation of 2-radix FFT (In-place algorithm). Sign = -1 is
  10  * FFT and 1 is inverse FFT. Applies the Discrete Fourier Transform (DFT) to
  11  * the data supplied in the buffer, which MUST BE power of two.
  12  */
  13 void complex_fft(const al::span<std::complex<double>> buffer, const double sign);
  14
  15 /**
  16  * Calculate the frequency-domain response of the time-domain signal in the
  17  * provided buffer, which MUST BE power of two.
  18  */
  19 inline void forward_fft(const al::span<std::complex<double>> buffer)
  20 { complex_fft(buffer, -1.0); }
  21
  22 /**
  23  * Calculate the time-domain signal of the frequency-domain response in the
  24  * provided buffer, which MUST BE power of two.
  25  */
  26 inline void inverse_fft(const al::span<std::complex<double>> buffer)
  27 { complex_fft(buffer, +1.0); }
  28
  29 /**
  30  * Calculate the complex helical sequence (discrete-time analytical signal) of
  31  * the given input using the discrete Hilbert transform (In-place algorithm).
  32  * Fills the buffer with the discrete-time analytical signal stored in the
  33  * buffer. The buffer is an array of complex numbers and MUST BE power of two,
  34  * and the imaginary components should be cleared to 0.
  35  */
  36 void complex_hilbert(const al::span<std::complex<double>> buffer);
  37
  38 #endif /* ALCOMPLEX_H */