Fast Fourier Transform of a real function

Hi! I got a question about the FFT properties; why FFT of a real function is not a real function as it is a property of Fourier transform? For example FFT of a gaussian function should be a gaussian, however, abs(fft(gaussian)) is a gaussian. thanks

Answer 1

[Walter Roberson]

That is not a property of the Fourier transform. The fft of a real function is generally complex and is always hermitian. The complex part is absent only if everything is in phase (e.g., the sum of sines)