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Topic: optimtool help
Replies: 3   Last Post: Feb 2, 2011 7:55 AM

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Torsten Hennig

Posts: 2,419
Registered: 12/6/04
Re: optimtool help
Posted: Feb 1, 2011 4:48 AM
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>
>
> Hi,
> sorry if this is not the place to post my problem.
> I have an over-determined system of equations
> representing a non-linear
> system and I thought if I could formulate the
> he problem as an
> optimization one, then I could use matlab's "fmtool"
> to solve it.
>
> My function is describes as:
>
> A_1 = sqrt((A_2^2)/4 + (1/(B^2))*(P-O)^2)) +
> sqrt(A_2^2)/4 +
> (1/(B^2))*(P+O)^2))
>
> I have "A_1", "P" and "O", and need to find
> (optimize) "A_2" and "B".
>
> How do I write the objective function and the
> constraints (I don't have
> any) ? I find the help section in matlab a bit
> inadequate and thin.
>
> Thanks,
>
> Kamran


If you write your function as
A_1^2 = (A_2^2/4+sqrt(A_2^2)/4)+1/B^2*((P-O)^2+(P+O)^2) =:
p1 + p2*((P-O)^2+(P+O)^2,
with
p1=A_2^2/4+sqrt(A_2^2)/4, p2=1/B^2
you see that you get a linear fit in the unknowns p1
and p2 under the restriction that both paramters have
to be >= 0.
You could first try to fit without restrictions on
the paramters (easy). If this does not help, try
fmincon.

Best wishes
Torsten.



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