[AstroPy] Bounds in parametric non linear fitting (astropy.modelling)

Nadezhda Dencheva dencheva at stsci.edu
Mon Jul 1 10:20:25 EDT 2013

Hi Andre,

It's a bug. Please file an issue on github.


From: astropy-bounces at scipy.org [astropy-bounces at scipy.org] on behalf of André Luiz de Amorim [streetomon at gmail.com]
Sent: Monday, July 01, 2013 8:45 AM
To: astropy at scipy.org
Subject: [AstroPy] Bounds in parametric non linear fitting (astropy.modelling)

Hi, I am using NonLinearLSQFitter and SLSQPFitter to fit some data to a parametric model I implemented. I am trying to set some boundaries in the parameters, as some values can not be negative. It seems that the bouns are set correctly, I ran the code in debug mode and the NonLinearLSQFitter._set_bounds() method is reached, for example. The code says this fitter accepts boundary constraints, but it does no work in my tests, the parameters step outside the bounds. In the case of SLSQPFitter it does not even fit, it returns the initial guess.

Attached is a minimal example showing my approach. I would like to know if I am using the API correctly before filing a bug report (and/or trying to fix it :-).



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