I was hoping someone could help me understand exactly how Matlab's FFT function deals with scaling axes. I am developing some Diffraction code that will simulate Fourier optics but I am hoping to understand how to interpret my results better with a simple example first.
Analytically the Fourier Transform of a f(x) = cos(bx) wave goes to F(k) = dirac(k-b)+dirac(k+b). My code to test this in Matlab is:
steps = 2^8; lim = 4*pi;
x=linspace(-lim, lim,steps);
b = 1;
func = cos(b*x);
Func = fftshift(fft(func));
which when plotted looks like this:
What I am trying to understand is how to rescale my k (spatial frequency) axis so the locations of the delta functions match the analytic result, which in this case should b at k = +/- 1.
This is my first time posting to these forums. Please inform and forgive me if I break any conventions. Any advice you could offer would be greatly appreciated!
