Hello all.

Just this simple question:

Let's say that H(ejw) is the frequency response of an ideal LPF, then my question is what is H(-ejw) ?? 

My guess, is that since I'm not changing w by -w, this is not a simply  frequency-reversal operation.

So, may I get any help from the experts?

Thanks

Negating z is a pi-rotation, so you get a high-pass filter.

Thanks.

Yeah. I just figured out my self by doing the math. Thank you anyway for the confirmation.