Re: Speed of lsim

[Geraint Paul Bevan]

SToyama wrote:
> Hi. I am a beginner of Octave, and I need some help to accelerate
> "lsim".
> As I want to simulate the response of a linear time-invariant state
> equation 
> to the arbitrary input signal, I tried to use "lsim". But I feel it's
> too slow.
> For example, it took about a minute to solve the step response of a
> simple 
> 1st order lag system, 1/(1+s).
> My Octave is version 2.1.36, my PC has Pentium-III 1.2GHz and 256MB-RAM 
> and OS is Windows XP Pro.
> I'm waiting for your good advice.
> Thanks.
> st

That is very slow, using octave 2.1.50 on an i686 running Debian/Linux 
it takes less than a second:

octave:1> sys = tf2sys(1, [1,1]);
octave:2> t = linspace(0,10,1001)';
octave:3> u = ones(1001,1);
octave:4> tic; lsim(sys,u,t); toc
ans = 0.33443

Are you using a pre-packaged version of octave or did you compile it 
yourself?


--
Geraint Bevan
Department of Mechanical Engineering
University of Glasgow
Tel: +44 (0)141 330 5917



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