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Reply-To: "Nasser Abbasi" <nma@12000.org>
From: "Nasser Abbasi" <nma@12000.org>
Newsgroups: comp.soft-sys.matlab
References: <gtpcaj$bk3$1@fred.mathworks.com>
Subject: Re: transfer function in a time constant form
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Date: Tue, 5 May 2009 06:10:54 -0700
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"pietro " <bracardi82@email.it> wrote in message 
news:gtpcaj$bk3$1@fred.mathworks.com...
> Is there a command to convert a trasfer function in zero pole form to time 
> constant form? Thanks in advance.

"time constant form" ?

You mean to get the equation of motion  from the tf?

something like this?

for example

EDU>> clear all
z = -0.5;
p = [0.1+i 0.1-i];
k = 1;
H = zpk(z,p,k);
tf(H)

Transfer function:
     s + 0.5
------------------
s^2 - 0.2 s + 1.01

EDU>> syms s
EDU>> ilaplace( (s + 0.5)/(s^2 - 0.2 *s + 1.01) )

ans =

exp(t/10)*(cos(t) + (3*sin(t))/5)


--Nasser