Subspaces of FMmlet transform

The subspaces of FM^mlet transform are investigated. It is shown that some of the existing transforms like the Fourier transform, short-time Fourier transform, Gabor transform, wavelet transform, chirplet transform, the mean of signal, and the FM^-1let transform, and the butterfly subspace are all special cases of FM^mlet transform. Therefore the FM^mlet transform is more flexible for delineating both the linear and nonlinear time-varying structures of a signal.