The same discrete set is obtained by treating the duration of the segment as one period of a periodic function and computing the Fourier series coefficients. Sine and cosine transforms: When the input function has odd or even symmetry around the origin, the Fourier transform reduces to a sine or cosine transform. Hartley transform Short-time Fourier transform (or short-term Fourier transform) (STFT) Rectangular mask short-time Fourier transform Chirplet transform Fractional Fourier transform (FRFT) Hankel transform: related to the Fourier Transform of radial functions.