Talk:Proper transfer function

Systems: Control theory Start‑class Low‑importance

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Is the current definition correct?

Is the current definition general enough? Currently it is only applicable to finite dimensional LTI systems. Would the high frequency result presented at the end of the article (which should probably be written as a limit) be a better definition? And then the current definition would be a result of the proposed definition when applied to FDLTI systems. Take for example a time lag. It has a unity amplitude frequency response, so it clearly fits the definition that I'm proposing, but it does not fit the definition currently in the article. Anyway, I'll search some texts to see if my suggestion is supported by the literature. If so, I'll post an edit unless someone objects. 128.250.5.248 (talk) 00:33, 14 August 2009 (UTC)[reply]

Frequency response approaches zero?

I question the statement:

A strictly proper transfer function will approach zero as the frequency approaches infinity.

${\textbf {G}}(\pm j\infty )=0$

which is true for all physical processes.

For example, a simple differentiator, such as a voltage-driven capacitor or a velocity-driven mass, has an improper transfer function and therefore an infinite frequency response at infinity.Roesser 14:37, 27 July 2007 (UTC) — Preceding unsigned comment added by 71.167.60.210 (talk) [reply]