sfft.m

function [ P1, f ] = ssfft( X, Fs )
%ssfft Computes the single-sided amplitude spectrum of a signal.
%   https://www.mathworks.com/help/matlab/ref/fft.html
%   [ P1, f ] = ssfft( X, Fs )
%
%   X       Input signal.
%   Fs      Sampling frequency.
%   P1      Single-sided Amplitude Spectrum.
%   f       Frequency range.
%
%   Plot with e.g. stem(f, P1), plot(f, P1).
   
L = length(X);        
Y = fft(X);
P2 = abs(Y/L);
P1 = P2(1:L/2+1);
P1(2:end-1) = 2*P1(2:end-1);
f = Fs*(0:(L/2))/L;

end