What format is required for Matlab LSIM Function input data?

Hi,

When using the LSIM function in Matlab with a dynamic transfer function object (z-domain), the required input signal (u,t) appears to be in a time domain!

However, I was expecting to pass LSIM the input signal in a z-domain because Y(z) = H(z)*X(z).

Please could you tell me

• Is LSIM transfering the input signal into the z-domain before calculating the output signal?
• Should I be passing LSIM a z-domain input signal (currently i get an error if i try to).

Thanks

Answer 1

[Star Strider]

The difference between continuous and sampled signals iis simply one of context. Ths signals sthemselves do not exist in z-space, only as functions of time, although sampled. (Continuous or ‘infinitely-sampled’ signals only occur with respect to analog hardware.) The system you are using with lsim may be defined in the z-domain, however the signals themselves are not. They are just signals sampled at discrete points in time.