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Re: Help with lsode


From: Ben Sapp
Subject: Re: Help with lsode
Date: Mon, 11 Feb 2002 09:07:07 +0700

Hi, 

Here is a simple example starting at t = 3.5 and going to t = 20.  Some lines 
have been cut out because they were used by me to check that I was doing 
things correctly.  (Like checking that my function worked.)  

octave:2>  function xdot = f(x,t)
> xdot(1) = x(1) + x(2) + exp(-t);
> xdot(2) = x(1);
> endfunction

octave:6> x0 = [4;pi]
x0 =

  4.0000
  3.1416

octave:8> t = 3.5:0.05:20;
octave:9> x = lsode("f",x0,t);
octave:10> plot (t,x)

On Monday 11 February 2002 1:54 am, Louie Strigari wrote:
> Hi,
> I'm new octave, first of all.
> I am trying to solve a first order ODE xdot = f(x,t) with initial
> conditions t0 = some number that's not zero, x0 = some number. I have
> reviewed the syntax for entering functions and using lsode, but the only
> thing I can find is where the initial condition t0 = 0 is used.
> Can some please show me the syntax for starting at a random initial time,
> t0 not necessarily = 0.
> Thanks.
>
>
>
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-- 
Ben Sapp                         Los Alamos National Laboratory
email: <mailto:address@hidden>   Phone: (505)667-3277
Fax:   (505)665-7920             URL:   http://www.neutrino.lanl.gov/
--



-------------------------------------------------------------
Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:  http://www.octave.org
How to fund new projects:  http://www.octave.org/funding.html
Subscription information:  http://www.octave.org/archive.html
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