MATLAB: Can anybody explain the commented line of the code

matrix manipulationrainflow

fs = 512;
X = [-2 1 -3 5 -1 3 -4 4 -2];
lX = length(X)-1;
Y = -diff(X)/2.*cos(pi*(0:1/fs:1-1/fs)') + (X(1:lX)+X(2:lX+1))/2;
% Y = [Y(:);X(end)];
plot(0:lX,X,'o',0:1/fs:lX,Y)

Best Answer

Are you asking this commented line?
% Y=[Y(:);X(end)];
Y(:) represents column vector having all elements (:)
X(end) represents the end element of X
New Y creates the all Y elements and last element of X.
See the following example for better understanding
>> X = [-2 1 -3 5 -1 3 -4 4 -2]
X =
         -2.00          1.00         -3.00          5.00         -1.00          3.00         -4.00          4.00         -2.00
>> Y=[1 2 3 4 5 6 7 8 9]
Y =
          1.00          2.00          3.00          4.00          5.00          6.00          7.00          8.00          9.00
>> Y=[Y(:);X(end)]
Y =
          1.00
          2.00
          3.00
          4.00
          5.00
          6.00
          7.00
          8.00
          9.00
         -2.00
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