sentences:  Auger and Flandrin showed that the method of reassignment, proposed in the context of the spectrogram by Kodera et al., could be extended to any member of Cohen's class of time-frequency representations by generalizing the reassignment operations to
  
  where formula_31 is the Wigner–Ville distribution of formula_1, and formula_33 is the kernel function that defines the distribution.They further described an efficient method for computing the times and frequencies for the reassigned spectrogram efficiently and accurately without explicitly computing the partial derivatives of
  phase.In the case of the spectrogram, the reassignment operations can be computed by
  
  where formula_35 is the short-time Fourier transform computed using an analysis window formula_36 is the short-time Fourier transform computed using a time-weighted analysis window formula_37 and formula_38 is the short-time Fourier transform computed using a time-derivative analysis window formula_39.