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Topic: (yet unsolved) how to Solve coupled ODEs
Replies: 4   Last Post: Feb 13, 2013 4:11 AM

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Posts: 1,717
Registered: 11/8/10
Re: (yet unsolved) how to Solve coupled ODEs
Posted: Feb 13, 2013 3:01 AM
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"Henry" wrote in message <kfeavo$2f$>...
> I modified the code to:
> tspan = linspace(1, 2,100);
> y = 0.0001*ones(1,200);
> [T,sols] = ode45(@yprime, tspan,y);
> and
> dyds = [dyds1' ; dyds2'];
> and it now runs, thanks.
> But I have this question: My odes are time-independent, function of "s" which is a distance, but since the ode45 will not work without a tspan, I came up with an arbitrary tspan. It looks as if ode45 interprets that "s" is a time? I'm confused as to how interpret the result of the routine which has dimensions of 100x200. I was expecting 1 x 200, i.e. independent of time.
> thanks

Just interpret your results for y(1) and y(2) as functions of distance, not of time.
So "tspan" in your case is a distance vector, not a time vector.

Best wishes

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