Autocorrelation sin(2x) function

Hi, I am trying to calculate the autocorrelation of the sin(2t), but I am getting a result different from the expected.

t = -10:0.05:10;

y = sin(2*t);

b = autocorr(y);

figure;

plot(b)

Expected :

found:

Answer 1

[aryan ramesh]

The autocorr(y) estimante the (ACF) of the univariate, stochastic time series y with confidence bounds.I was looking for the xcorr() function.