Does the frequency response assume the zero input response to be 0?

I'm a bit confused about the frequency response and the state of a system. Is it simply the ratio of the output of the zero state response to the input of the zero state response? Or does it include the zero input response? Any clarifications would be greatly welcomed.

• there seems to be some confused semantic. i dunno if, by "frequency response", you mean LTI system (or filter) or something else. Matt may have guessed correctly. frequency response is either (A) the ratio of the output Fourier Transform to the input Fourier Transform evaluated as a complex function of frequency, $f$ or $\omega$.or (B) the log of (A) usually expressed in dB and degrees (but the mathematical natural units would be nepers and radians.) – robert bristow-johnson Jan 31 '17 at 8:38