Considering that the objective is to remove a linear trend, perhaps the easiest way would be:
t = 11:22;
p = polyfit(x(t),tac(t),1);
d_tac_ts_2 = tac - polyval(p, x);
Here, ‘x’ is the original independent variable vector that defines ‘tac’ as the dependent variable.
Plotting the result would be:
figure
plot(x, tac)
hold on
plot(x, d_tac_ts_2)
hold off
grid
To plot both the original and detrended data.
