[SciPy-user] Re: SciPy-user Digest, Vol 22, Issue 3

Steve Schmerler elcorto at gmx.net
Tue Jun 28 07:23:45 CDT 2005


Hi,

or you can use mpfit for constrained optimization which is a (quite 
fast) pure Python implementation of MINPACK's LMFIT routine.

http://cars9.uchicago.edu/software/python/index.html -> mpfit.py
 
http://www.scipy.org/mailinglists/mailman?fn=scipy-user/2005-February/004104.html 


I did some little bugfixes in this code (see attachment) and used it for 
some time without problems.

cheers,
steve


Christian Kristukat wrote:
> aurelien.gourrier at free.fr wrote:
> 
>> Hi all,
>>
>> Can anyone tell me if there is a possibility to use constraints on the 
>> leastsq
>> method ? I need to do some bounded minimization of gaussians or 
>> lorentzians on
>> 1-D data and couldn't find any way out so far...
> 
> 
> One method I'm using to add simple bounds is to map the parameters to 
> some limits before calculating the residuals.
> 
> def residuals(a):
>     # mapping +/-inf to +/-1
>     t = a/(abs(a)+1.0)
> 
>     # amin/amax are 1D arrays containing the bounds
>     # map -1/+1 to amin/amax
>     a = (amin+amax)/2.0+(amax-amin)/2.0*t
>     
>     # avealuate the function
>     newy = func(a)
> 
>     return  y-newy
> 
> Regards, Christian
> 
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> 
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