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Topic: fsolve - premature and stalled
Replies: 3   Last Post: Apr 4, 2013 8:55 AM

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Alan Weiss

Posts: 1,267
Registered: 11/27/08
Re: fsolve - premature and stalled
Posted: Apr 4, 2013 8:17 AM
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On 4/4/2013 7:39 AM, KUNHEE wrote:
> Hi, I am trying to use fsolve for a problem I need to solve.
>
> The code works perfectly for one case (cartesian equations) but when
> modified to adopt axisymmetric, it does not work.
>
> The error message shows :
> "fsolve stopped because the relative size of the current step is less
> than the
> default value of the step size tolerance squared and the vector of
> function values
> is near zero as measured by the default value of the function tolerance."
>
> I have checked the coding several times but I am unable to fix this
> problem.
> I believe it is a problem with optimisation and to do with function
> solution tolerances. I tried loosening up on MaxFunEvals, MaxIter,
> which eliminated problem with premature stops, but I still have
> stalling problem. I also tried TolFun and TolX, unfortunately, no
> improvement.
>
> If anyone could suggest a solution or point me in the direction, or
> just anything.....I am struggling big time.
>
> **SNIP**
> Anyhelp will be greatly appreciated
> Thanks a lot for even reading this long post
> Thanks a lot
>
> Regards,
> Thanks a lot


The exit message does not indicate a problem, and, indeed, fsolve told
you it found a solution: "... the vector of function values is near zero
as measured by the default value of the function tolerance."

Did you check to see if the solution was satisfactory? I bet it is.

Alan Weiss
MATLAB mathematical toolbox documentation



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