Setup frequency array properly
Posted for anyone who may find this useful...

I created a picture that shows DFT frequency bin spacing for odd and even cases of N where N is the number of samples.  FFTs usually operate on an even number of samples (the algorithm works by repeatedly breaking the problem into halves), so only the even case applies.  The DC component (0*fs) is always part of the computation .  The bin at the nyquist frequency (fs/2) only shows up for the even case.  The frequencies above the nyquist frequency reflect back on the negative side of the frequency axis in reverse order.  For real signals the reflected FFT values are complex conjugates of their positive counterparts.  There are two specific cases depicted on the complex plane, N=5 for the odd case and N=8 for the even case.