Dear Mr Cao,
I am dealing with 20 channels of 50 Hz acceleration data to perform system identification and extraction of modal parameters. I found your code very helpful!
A short question:
- during the for-loop (line 51 to 54 in the code) You fill the future- and past-Block-Hankel matrix (Yf,Yp) with shifted blocks of the time series.
I was wondering if the order within the past-matrix "Yp" is changed due to the LQ-decomposition?
Here, Yp is filled from bottom to top, "max past" is at the bottom "min past" is at the top. As far as I understand some papers "max past" is at the top and "min past" is at the bottom, so that there is only one time shift between the bottom of Yp and the top of Yf when performing Yh=[Yp;Yf]?
Yp could be filled analogue to Yf?:
Yp((k-1)*n_y+1 : k*n_y, :) = sy(:, k : k+N-1);
The version of perms has a bug. It sometimes gives the even permutations instead of the odd permutations and vice versa. It has been corrected and reissued as FX32978. This version, FX10237 should soon be deleted.
30 Jan 2009
even, odd, cyclical, unique permutations of a set of vectors