Difference between $\tt fft$ and $\tt dftmtx$ in MATLAB

1. What is Matlab Dftmtx?
2. What is the difference between fft and Fftshift?
3. How do you find the DFT matrix in Matlab?

What is Matlab Dftmtx?

A discrete Fourier transform matrix is a complex matrix whose matrix product with a vector computes the discrete Fourier transform of the vector. dftmtx takes the FFT of the identity matrix to generate the transform matrix. For a column vector x , y = dftmtx(n)*x. is the same as y = fft(x,n) .

What is the difference between fft and Fftshift?

fft computes the discrete Fourier transform and by definition the output is complex. fftshift doesn't compute anything except swaping the position of the samples, so if your input is real, you get real output.

How do you find the DFT matrix in Matlab?

W N = e - j 2 π / N . Note The MATLAB convention is to use a negative j for the fft function. This is an engineering convention; physics and pure mathematics typically use a positive j. fft , with a single input argument, x , computes the DFT of the input vector or matrix.