Re: nonlin_min function

[Steph Bredenhann]

On 2020/04/06 10:54, Kai Torben Ohlhus wrote:

> On 4/6/20 2:49 PM, Steph Bredenhann wrote:
> > [...]
> >
> > The variables are as follows, and please note that the values after %
> > for GPL_Do, etc are the values as calculated with Excel SOLVE function:
> >
> > [...]
> >       
> Dear Steph,
>
> I attached all necessary codes as m-files.
>
> Maybe there is a typo in your function "fn_BBR_GPL_RMSE()"?  In short:
>
>    Dcalc = D = D0 + D1*t.^m;
>    SRE = (D-Dcalc)./D;
>
> In this case "SRE" is always zero, as "Dcalc = D" and no progress seems
> to happen.  Furthermore "D" seems to be an input parameter of
> "fn_BBR_GPL_RMSE()", which is unused then.
>
> HTH,
> Kai
>

Dear Kai

I have now abandoned nonlin_min and rather use fsolve, see attached edited .m files

The output is and seems quite good, will test further:

GPL parameters:
D0 = 0.000557218
D1 = 0.000053334
m  = 0.399999
GPL_RMSE  = 1.096952
fsolve outcome: GPL_cvg = 0:  maximum number of iterations exceeded   Iterations = 75

As you can see fsolve terminate with maximum iterations exceeded. Iterations reported = 75, however the fsolve default is 400 and although I increased MaxIter to 1000 the outcome stays the same. I assume the tolerances were met, but I still try to understand the tolerances, I work with defaults.

Any comments/improvements will be appreciated.

--
Steph

call_script.m
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fn_BBR_GPL_RMSE.m
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