Matlab FFT Frequency Axis Reconstruction

Time and time again, I find myself needing to remember how to accurately reconstruct the frequency axis of an FFT in Matlab. This is one of the ways that I have documented as being a pretty close approximation of the frequency axis. This code will also properly compute the magnitude of each frequency component.

The code below uses the signal below as an example:

y=5*sin(10*2*pi*x)+3*sin(22*2*pi*x)+cos(13*2*pi*x)+7;

Now the Code:


Now the result:


Hope you find this useful.