Fourier transform conjugate pairs definition

Hi, I'm currently using matlab to simulate quantum systems, and I wish to test the accuracy of my approximation to the actual system. My codes involve a series of fft and ifft, and in between these transformations I would need to have multiply each transformed term by a phase factor i.e e^(1i.*dt.*(a function of x)) (I'm doing approximations on unitary time evolution if that helps clarify what I mean). So, I would need my conjugate pairs, x and p to be defined properly such that it gives me a correct relation between them. For simplicity sake I have let hbar to be 1. Please help!

Answer 1

[Abhishek Ballaney]

https://in.mathworks.com/help/matlab/ref/fft.html

[Leo Chang]

Do u really think that I haven't searched for fft on my own?