Simulink timeseries conversion into matrix

Hello,

I have a timeseries of Y positon output from simulink block. Y in converging to the steady state from t = 0 to t =50. I want to calculate the root mean square deviation(RMSD) of every second of input Y while simulating and check when it drops below the set thrushhold of RMSD. How to create a matrix of elements for each second and calculate the RMSD. When thrushhold for RMSD is reached output from matlab function should be 1 else 0.

This is how I post processed the data after importing into matlab from simulink. The same has to be implemented in simulink.

time = Y_position.Data(3500:end,1);
v = Y_position.Data;
mean = 2.063;
a = (time + mean);
N = size(time);
for ii = 1:N
   b(ii,1) =(a(ii,1) )^2;
   sumb = sum(b);
end
c = sum(a);
MSE = sumb/N(1,1) % Mean square error (MSE)
RMSD_ = sqrt(MSE) % Root Mean square Deviation (RMSD)