How to obtain the FUNCTION for the following smooth curve? x 0 100 250 500 1000 4000 y 1.8 1.2 1.02 0.99 0.97 0.85 Thanks, SJ --------------------------------- [[alternative HTML version deleted]]
There are infinitely (uncountably) many of them. Which one do you want? jk/ On Thu, 20 Oct 2005, Xiaodong Jin wrote:> How to obtain the FUNCTION for the following smooth curve? > x 0 100 250 500 1000 4000 > y 1.8 1.2 1.02 0.99 0.97 0.85 > > Thanks, > SJ > > > --------------------------------- > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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 >
y ~ 1/(a + b*x^c) looks pretty good to me. If we assume a starting value of c=1 then we can get the starting values of a and b from lm(1/y ~ x) and then do an nls fit. On 10/20/05, Xiaodong Jin <close2ceo at yahoo.com> wrote:> How to obtain the FUNCTION for the following smooth curve? > x 0 100 250 500 1000 4000 > y 1.8 1.2 1.02 0.99 0.97 0.85 > > Thanks, > SJ > > > --------------------------------- > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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 >