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What are all the options to improve Fsolve?

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farzad on 4 Jun 2019
Edited: Matt J on 5 Jun 2019
Hi All
Using FSolve , to solve a set of non linear equations , I get warnings like :
optimization terminated : first order optimality is less than options.TolFun.
I added :
options = optimset('MaxFunEvals',1e20);
to use as options, is it enough ? too high ? too low ?
and what are all the options that I can deliver a precise solution ?


Torsten on 4 Jun 2019
The message you obtain is not a warning, but you are informed that the calculation has been successfully terminated.
farzad on 4 Jun 2019
Thank you very much
Exit Flag for both of the case that the results were desirable and for the case that they had error and not as expected
exitflag : 1
what does Output and fval say ?
how can I increase the solution precision ?

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Accepted Answer

Matt J
Matt J on 4 Jun 2019
The complete list of fsolve options is given here
Generally, speaking, they are tweak parameters, i.e., the best values of these parameters will be problem specific. You should, in any case, check the exitflag output,
[x,fval,exitflag,output] = fsolve(___)
to interpret why fsolve stopped, and if it thinks it was successful.


Show 2 older comments
farzad on 4 Jun 2019
I use MATLAB 2007 , it seems many of the options bug me with the error
too many input arguments
Matt J
Matt J on 5 Jun 2019
Documentation for older versions of Matlab can be found here
You need to consult the R2007 documentation page for fsolve to read about the options avaialble and their meanings. Optimoptions replaced/deprecated optimset in later versions of Matlab. Both allow you to set multiple option parameters in the same call, however. The page for optimset in R2007a, lists this as the first syntax

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