Siril gaussian function

Since I want to use Siril to calculate FWHM in my Bachelors thesis I wanted to find out how Siril fits the gaussian function around a star. I looked at the source code, but I am not well versed in c so I can’t quite make sense of it and it does not quite resemble the way I know of how to fit gaussian functions to measure star FWHM as far as I can tell.

G(x,y)=B+Aexp( −((x−xi)^2 +(y−yi)^2􏰙) /2σ^2) this is the formula I know of, but the form used in the source code seems to have a slightly different form.

I would just need the basic gaussian function the software uses, so I can put it in my thesis. Thank you!

Hello, I’m not the one who wrote this code, which was made in Matlab and converted to C if I remember correctly, but you may find information on this page if you haven’t seen it already: Siril:PSF - FreeAstro . Indeed it’s not easy to understand, as it’s mostly arranging data into matrices and vectors to let GSL solve the thing in the end…

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Thank you very much, this is what I was looking for! I must have missed this page, this answers my questions

Just to let you know, I’ve updated the link, it was leading to a badly formatted page. Also, I’ve just created that about aperture photometry: Siril:Photometry - FreeAstro