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## Re: Multiple variables in ode45

 From: Paul Probert Subject: Re: Multiple variables in ode45 Date: Mon, 05 Dec 2005 22:23:42 -0600 User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.8) Gecko/20050831 Debian/1.7.8-1sarge2

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*(e-1.14*Vf_dot)

where e = Vf-Vl, 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

You might want to take a look at daspk, for solving problems
like 0=f(x,xdot,t) where you supply the f. Just lump all your variables
into one big system and let 'er rip. Works great for me!

hth,
Paul Probert
University of Wisconsin

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