How to compute the value in one point through the transferfunction?

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tqy on 19 Sep 2012
Dear all,
I has a transferfuntion H(s), I want to know the amplitude and phase in a particular point, for expample, if s = 1+j.
I don't know how to do this , can anybody help?
Thanks a lot~~~

Honglei Chen on 19 Sep 2012
First of all, please delete duplicate thread. Second, your question is not clear. You have H(s), isn't it just plug 1+j into it?
tqy on 20 Sep 2012
Yes, I have H(s), I don't how to plug 1+j into it, use function "subs"? It seems doesn't work.
The type of H(s) is "tf", with the Laplace variable "s", so my question is how to replace "s" with "1+j". Any function can do this?
Thank you.

Honglei Chen on 20 Sep 2012
I think the following is what you mean.
s = tf('s')
H = s/(s^2+2*s+10)
evalfr(H,1+1i)

1 Comment

tqy on 21 Sep 2012
Thank u very much! That's what I want.

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