From: Simple <qsb_at_nlbmol.ibp.ac.cn>

Date: Sun 02 Oct 2005 - 00:45:29 EST

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Sun Oct 02 00:53:40 2005

Date: Sun 02 Oct 2005 - 00:45:29 EST

Thanks for your kind respond. Although the answer didn't solve my question clearly,maybe I still not understand the art of R.

I'm sorry that I had not talked the problem clearly, maybe a example with more detail will be suitable as suggested in the the posting guide.

In function fitting program, such as Sigmaplot, a fitting formula, can be
write in separate form:

G=a+(b*x)^(1/2)

k=exp((G-G0)/(R*T))

fit k to y

of course,in R's nls, can write as:

mynls<-nls(formula=y~exp((a+(b*x)^(1/2)-G0)/(R*T)),data=mydata,...)

In this example, the formula is simple and acceptable. However, when the formula is more complexity,writing all in one formula,the readability will be damaged.So I'm looking for a way to write simple and readable code in this situation.

Spencer Graves wrote:

> I'm not certain what you are asking.

*>
**> You can build expressions in R as character strings and then execute
**> them. Example:
**>
**> expr <- paste("two <-", 1, "+", 1)
**> eval(parse(text=expr))
**> two
**>
**> If this does not answer your question, PLEASE do read the posting
**> guide, "www.R-project.org/posting-guide.html". It can help increase the
**> chances of a quick and useful reply.
**>
**> spencer graves
**>
**> Simple wrote:
**> > hi,
**> > I'm an newbie for R,I want do some fitting in R.
**> >
**> > I wander if it is possible to write a few of equations but only one
**> > formual when fitting
**> >
**> > Currently,My problem is,in R, is there methods combination a few
**> > equations into one formual?
**> > For example,
**> > y=f1(k);
**> > k=f2(t);
**> > t=f3(x);
**> > although it is certain that the can be equations turn into one formual as
**> > y~f(x),but write such a complexity string make me painful.
**> >
**> > I have searched the web and found out there were only examples with one
**> > formual.any suggestion?
**> >
**> > I hope that I have omit something.
*

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Sun Oct 02 00:53:40 2005

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