
From:  Ron Crummett 
Subject:  Re: Multiple variables in ode45 
Date:  Tue, 06 Dec 2005 09:50:23 0800 
Useragent:  Mozilla Thunderbird 1.0.7 (X11/20050923) 
Anyway, to the actual question. Vl is the velocity of the lead vehicle and I have defined it to start at 0, then climb to 13.4 (m/s, 30 mph) over 5 seconds, hold constant for 10 seconds, and then drop back to 0 over 3 seconds. So it is a piecewisedefined function, I guess that's the best way to put it. I hope that helps, and thanks so much for the help given me.
Ron Shai Ayal wrote:
I'm not sure I understand  is Vl a function or constant?In general you e to solve your two equations (for u_dot and Vf_dot) simultaneously, and ide45 should be able to do this.Shai Ron Crummett wrote:Hi all I am trying to solve a differential equation with ode45 that has two input variables and one output, but one of the input variables is dependent on the other. When I try searching for anything like this it is to no avail (maybe I don't know what to search for).Anyway, the equation is u_dot = 0.5*e_dot+1.64*(e1.14*Vf_dot)where e = VfVl, Vl is my input, and Vf is my output. The value of u is then fed into another system (which I do have the diff. eq. for) to get Vf, if that helps.Could someone give me some pointers on how to do this? Thanks. Ron  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 
 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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