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Does ode45 allow symbolic variables in its ode definition?

Asked by weiwei

weiwei

on 22 Jul 2011

The same as my title. Thanks a lot!

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weiwei

weiwei

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1 Answer

Answer by Jan Simon

Jan Simon

on 22 Jul 2011

Inside the ODE function you can do what ever you want, as long as the output is numerical and has a certain degree of smoothness.

4 Comments

Walter Roberson

Walter Roberson

on 22 Jul 2011

If you have known values at selected points for an ODE, but you do not know the form of the ODE, then I do not think it is possible to reconstruct the ODE uniquely without an infinite number of samples.

Jan Simon

Jan Simon

on 23 Jul 2011

@Weiwei: It sound feasible. This is actually a standard parameter estimation of a boundary value problem on the subintervals. So start with a good coice of a,b,c, calculate the ODE and find better a,b,c by a variation or the evaluation of the sensitivity matrix. If your trajectories explode if a,b,c are far apart from the solution, use a multiple shooting method. The objective of your parameter estimation is than the distance between your trajectory from all mesaurements *and* the steps at each measurement point.

weiwei

weiwei

on 24 Jul 2011

As far as I know, the lsqnonlin function in Matlab is able to do parameter estimation using least square minimization. However, it requires an input of function definition. I cannot find a way to couple ode45 with lsqnonlin to do the above described work.

Jan Simon

Jan Simon

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