dftmtx Computes n-by-n Discrete Fourier transformation matrix. d = dftmtx(n) n: Real positive scalar number This fuction gives a complex matrix of values whose product with a vector produces the discrete Fourier transform. This can also be achieved by directly using the fft function i.e. y=fft(x) is same as y=A*x where A=dftmtx(n). Sonu Sharma, RGIT Mumbai (fellow at FOSSEE, IIT Bombay)