From help-octave-request at bevo dot che dot wisc dot edu Mon Feb 11 10:03:49 2002 Subject: Re: Help with lsode From: Ben Sapp To: Louie Strigari , help-octave@bevo.che.wisc.edu 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. > > > > ------------------------------------------------------------- > 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 > ------------------------------------------------------------- -- Ben Sapp Los Alamos National Laboratory email: 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 -------------------------------------------------------------