Please accept my apologies as I was in fact wrong. It was not my intention to attack minpack.lm or criticize the maintainer. I like minpack.lm and am fully aware of the effort involved in rewriting the code. Next time I'll use more careful wording.
Thanks also to Professor Nash for his efforts. I look forward to the results. Best regards, Michael unaffiliatd > Gesendet: Freitag, 21. Oktober 2016 um 09:39 Uhr > Von: "Berend Hasselman" <b...@xs4all.nl> > An: "Mike meyer" <1101...@gmx.net> > Cc: ProfJCNash <profjcn...@gmail.com>, "r-help@r-project.org" > <r-help@r-project.org> > Betreff: Re: [R] nls.lm > > > > On 21 Oct 2016, at 06:00, Mike meyer <1101...@gmx.net> wrote: > > > > Let's take a different view of the problem. > > Given f=(f_1,...,f_m):R^n -> R^m we want to minimize ||f(x)||. > > > > What distinguishes this from a general minimization problem is that you > > know the structure of the > > objective function F(x)=||f(x)||² and have the individual constituents f_j. > > Make use of that information as appropriate. > > > > This is more general than trying to solve the system f(x)=0 or fitting a > > model to data. > > In this more general setting notions such as underdetermined/overdetermined > > system do not apply. > > > > The restricted view of model fitting serves only to confuse the issue. > > For that reason it is (in my view) a bad idea to force the user to set up > > his problem in > > R-model notation. > > > > I assume that you have been referring to the R package minpack.lm. > > I've had a look at the underlying Fortran code (from Minpack and developed by > More et.al. made in a distant past) as used by the package. > That underlying code returns an error when the condition: number of > functions (m) >= the number of independent variables (n) > is not satisfied i.e. when m < n. > > Making that more general would entail a lot of thinking and reworking of the > code. As far as I can see it is not possible to just remove the condition > m>=n from the underlying Fortran. More (possibly many) changes would be > required. Blaming R and/or the package author/maintainer is unfair. > > If you require a more general version of the algorithm or if you want > something else you will have to roll your own package/code. > If you don't feel that minpack.lm is appropriate for your application and you > want changes you'll have to discuss matters with Moré > (http://www.mcs.anl.gov/~more/) if I got the correct link. > > Berend > > ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.