Hello,
I can tell you what happened: for some values of lambda and some values
of K(4,5,6), your function is undefined and the leastsq goes kaboom!
It is never a good idea to fit a function that can become undefined for
some parameters/xvalues.
Try to redefine the function you fit to avoid any undefined values.
Antoine
I was able to use the range [1:51], but not [1:52].
Le 27/08/2020 à 16:52, Dang Ngoc Chan, Christophe a écrit :
Hello all,
Let's talk about optics.
I have a glass, its refraction index n varies with the wavelength lamba.
I have a CSV file with the corresponding data (verre_HOQ.cvs attached), 52
points.
I want to model this with the Sellmeier model
https://en.wikipedia.org/wiki/Sellmeier_equation
and use for this the attached script (regression_sellmeier.sce).
Mind to set the path at line 7 of the script if you want to run it.
My problem:
I can run piecewise regression,
i.e. it runs when I work with the points 1 to 25, 13 to 39, or 32 to 52;
e.g. at lines 11 and 12, it works when I use
// ----------
lambda = 1e-3*donnees(1:25, 1); // en µm
nexp = donnees(1:25, 2);
// ----------
but when I try to extend these ranges (and of course when I try to use all the
points),
it fails with the following error:
5215700pt: Wrong type for output argument #1: Real scalar expected.
Can anyone tell me what goes on here?
Regards
--
Christophe Dang Ngoc Chan
Mechanical calculation engineer
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