From mathieu.ribatet at epfl.ch  Fri Aug  8 15:29:30 2008
From: mathieu.ribatet at epfl.ch (Mathieu Ribatet)
Date: Fri, 08 Aug 2008 15:29:30 +0200
Subject: [Rd] Suggestion for the optimization code
In-Reply-To: <alpine.LFD.1.10.0808081405100.7967@gannet.stats.ox.ac.uk>
References: <489C4293.2080806@epfl.ch>
	<alpine.LFD.1.10.0808081405100.7967@gannet.stats.ox.ac.uk>
Message-ID: <489C4A3A.7040104@epfl.ch>

Ok, please consider it as a bad call.
Thanks for your answers.
Best,
Mathieu

Prof Brian Ripley a ?crit :
> On Fri, 8 Aug 2008, Mathieu Ribatet wrote:
>
>   
>>   Dear list,
>>
>> Here's a suggestion about the different optimization code. There are several
>> optimization procedures in the base package (optim, optimize, nlm, nlminb,
>> ..). However, the output of these functions are slightly different. For
>> instance,
>>
>>  1. optim returns a list with arguments par (the estimates), value the
>>     minimum (maxima) of the objective function, convergence (optim
>>     .convergence)
>>  2. optimize returns a list with arguments minimum (or maximum) giving
>>     the estimates, objective the value of the obj. function
>>  3. nlm returns a list with arguments minimum giving the minimum of
>>     the obj. function, minimum the estimates, code the optim. convergence
>>  4. nlminb returns a list with arguments par (the estimates),
>>     objective, convergence (conv. code), evaluations
>>
>> Furthermore, optim keeps the names of the parameters while nlm, nlminb don't.
>> s
>> I believe it would be nice if all these optimizers have a kind of homogenized
>> output. This will help in writing functions that can call different
>> optimizers. Obviously, we can write our own function that homogenized the
>> output after calling the optimizer, but I still believe this will be more
>> user-friendly.
>>
>> Do you think this is a reasonable feature to implement - despite it isn't an
>> important point?
>>     
>
> This would be essentially impossible without breaking most existing code,
> and in the case of optimize() and nlminb() that goes back many years to
> uses in S(-PLUS).
>
>   
>> Best,
>> Mathieu
>>
>> * BTW, if this is relevant, I could try to do it.
>>
>> --
>> Institute of Mathematics
>> Ecole Polytechnique F?d?rale de Lausanne
>> STAT-IMA-FSB-EPFL, Station 8
>> CH-1015 Lausanne   Switzerland
>> http://stat.epfl.ch/
>> Tel: + 41 (0)21 693 7907
>>
>> ______________________________________________
>> R-devel at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>>     
>
> --
> Brian D. Ripley,                  ripley at stats.ox.ac.uk
> Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
> University of Oxford,             Tel:  +44 1865 272861 (self)
> 1 South Parks Road,                     +44 1865 272866 (PA)
> Oxford OX1 3TG, UK                Fax:  +44 1865 272595
>   

-- 
Institute of Mathematics
Ecole Polytechnique F?d?rale de Lausanne
STAT-IMA-FSB-EPFL, Station 8
CH-1015 Lausanne   Switzerland
http://stat.epfl.ch/
Tel: + 41 (0)21 693 7907



[Rd] Suggestion for the optimization code
Mathieu Ribatet