Re: [Help-gsl] Linear fitting

[Patrick Alken]

Francisco,

  You have some errors in the way you handle your 2D arrays. I have 
made a small modification to define new 1D arrays (x and y) and store 
your fit data into those arrays. The program output now says:

Performing fit with 20 points...done! (status = 0)
====== BET results ======
y = 0.000022 + 0.005321 x
[2.54531e-11, -1.26944e-10
 -1.26944e-10, 8.07463e-10]
Chi Square = 0.000000
=========================

My changes are attached - you can find the lines I changed with the "PA" 
keyword

On 05/03/2018 04:13 AM, Francisco M Neto wrote:
> Greetings!
>
>         I have been trying to use gsl for some linear least squares
> fitting, but for some reason I'm getting bad results.
>
>         Instead of returning the results of the fit, gsl_fit_linear()
> returns -nan for all parameters. I'm not sure if I'm passing something
> wrong to it, but I do know that there is no problem with the data (I've
> ran it through other LS fitting procedures and results are consistent).
>
>         Attached are the source and an example data file. I've compiled
> and ran with:
>
> $ gcc -I/usr/include/gsl/ -lm -lgsl -lgslcblas -o teste_bet teste_bet.c
>
> $ ./teste_bet data.dat

teste_bet.c
Description: Text Data