“…Among orthogonal transforms, fractional orthogonal transforms have been extensively applied in signal processing during the past decades. They include FrFT [21, 22], fractional cosine transform [23, 24], fractional sine transform [23, 24], fractional Hartley transform [23, 24], fractional Hilbert transform [25], fractional wavelet transform [26], fractional random transform [27], fractional Mellin transform [28], fractional Gabor transform [29], fractional S transform [30], convolution‐based fractional transform [31], multiple‐parameter FrFT (MPFrFT) [32–35], and so on. Mathematically, this kind of transforms, which is a generalisation of the corresponding conventional transforms, can be regarded as a rotation of signals in the time–frequency plane and therefore has attracted much attention [23].…”