Hi!
Some weeks ago I discovered R. Now, I have a somewhat complicated task
and am not sure whether R is the right tool to solve it.
I got data of several series or measurements where I have to find the
two inflection points. I did a linear regression (with ^2 and ^3
arguments), the problem there was that I had to look only at a very
narrow band of measurement in order to get the approximation right at
the essential point. (Maybe there is a better way than lm?)
Now that I have an appromiated function, I need its inflection point,
but I could not find any R function for that. Is there any? Or can
anyone recommend a good (possibly free) mathematical programme?
Maybe this could be helpful: All the measurements look like this and I
marked the points of interest.
,-------
/
/ <--
/
,----??
/
| <--
/
-----??
Thank you very much for your help
Martin
take a look at predict.smooth.Pspline in the package pspline... url: www.econ.uiuc.edu/~roger Roger Koenker email rkoenker at uiuc.edu Department of Economics vox: 217-333-4558 University of Illinois fax: 217-244-6678 Champaign, IL 61820 On Jul 1, 2004, at 10:49 AM, Martin aus Chemnitz wrote:> Hi! > > Some weeks ago I discovered R. Now, I have a somewhat complicated task > and am not sure whether R is the right tool to solve it. > > I got data of several series or measurements where I have to find the > two inflection points. I did a linear regression (with ^2 and ^3 > arguments), the problem there was that I had to look only at a very > narrow band of measurement in order to get the approximation right at > the essential point. (Maybe there is a better way than lm?) > > Now that I have an appromiated function, I need its inflection point, > but I could not find any R function for that. Is there any? Or can > anyone recommend a good (possibly free) mathematical programme? > > Maybe this could be helpful: All the measurements look like this and I > marked the points of interest. > > ,------- > / > / <-- > / > ,----?? > / > | <-- > / > -----?? > > > Thank you very much for your help > > Martin > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html
does locpoly in package KernSmooth help? Martin aus Chemnitz wrote:> Hi! > > Some weeks ago I discovered R. Now, I have a somewhat complicated task > and am not sure whether R is the right tool to solve it. > > I got data of several series or measurements where I have to find the > two inflection points. I did a linear regression (with ^2 and ^3 > arguments), the problem there was that I had to look only at a very > narrow band of measurement in order to get the approximation right at > the essential point. (Maybe there is a better way than lm?) > > Now that I have an appromiated function, I need its inflection point, > but I could not find any R function for that. Is there any? Or can > anyone recommend a good (possibly free) mathematical programme? > > Maybe this could be helpful: All the measurements look like this and I > marked the points of interest. > > ,------- > / > / <-- > / > ,----?? > / > | <-- > / > -----?? > > Thank you very much for your help > > Martin > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html-- -------------------------------------------- Thomas Cornulier Centre d'Etudes Biologiques de Chiz?? - CNRS 79360 Beauvoir sur Niort +33 (0)549099613 / fax +33 (0)549096526 mobile +33 (0)620660784