use fsolve with boundaries

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Franziska on 22 Jan 2013
I wonder if there is a way to use fsolve with boundaries?
I am currently using fsolve for a system of nonlinear equations solving for up to 100 variables. The values I get are ok, but unfortunately not in the bounds I want to look. Is there a way to bound the variables?
Thanks a lot.

Accepted Answer

Matt J
Matt J on 22 Jan 2013
LSQNONLIN is basically an extension of FSOLVE that allows for upper and lower bounds.
Shashank Prasanna
Shashank Prasanna on 22 Jan 2013
Other than dogleg, FSOLVE and LSQNONLIN use the same algorithm and are only different in the sense that FSOLVE performs the sum of squares internally. FSOLVE just does not have an interface for constraints but the algorithm is capable of it, in which case the user may revert to LSQNONLIN.
FMINCON was just a suggestion, and as you noted, not the best in this scenario, but my comment was about comparing LSQNONLIN to FSOLVE in-terms of one being an extension of the other.

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More Answers (2)

Shashank Prasanna
Shashank Prasanna on 22 Jan 2013
Unfortunately as you mentioned FSOLVE does not do constraints as of currently. As an alternative and with no guarantees as always, you can try to use FMINCON with constraints such that it minimizes the |F(x)| in a least square sense there by forcing each equation to zero. Your mileage may vary.

Franziska on 23 Jan 2013
Thanks. - LSQNONLIN works perfect.

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