How can I extract steady state information of a given system response?

Dear Matlab users

I have collected some faulty data of a polymerization palnt. I need to extract only steady state information. In other words I want to remove the transient behaviour. Is there any funcyion which can do this for me?

[Ameer Hamza]

Can you share the data or its plot? It will show what type of transients are present.

[Reyhane Mokhtarname]

Dear Ameer Hamza

actually I want to use the data as training samples for fault detection algorithm. I have 12 process variables which are projrcted in to principle component and residual subspaces. Number of PCs in my case is 3. The steady state data are under the ellipsoid. I want to remove data points above the ellipsoid.