function Y = qfft(X, A, L)% QFFT Discrete quaternion Fourier transform.%% This function calculates the fast quaternion Fourier transform of% (columns of) X. A specifies the transform axis (that is the direction% in 3-space of the vector part of the hypercomplex exponential). It must% be a pure quaternion (real or complex) but it need not have unit modulus.% L specifies whether the quaternion exponential is on the left ('L') or% right ('R').%% See also: IQFFT, FFT, IFFT.% Copyright