fftplot.m

function fftplot(x, Fs, N)
    if (~exist('N', 'var'))
        N = 2^nextpow2(length(x));
    end
    X = fft(x, N);    
    f = (0:(N-1))/N*Fs;
    ind = find(f > Fs/2,1,'first'); % grab only first half of the spectrum    
    
    % Plot single-sided amplitude spectrum.
    plot(f(1:ind), 2*abs(X(1:ind))) 
    title('Single-Sided Amplitude Spectrum of x(t)')
    xlabel('Frequency (Hz)')
    ylabel('|X(f)|')
end