On 16-11-2012, at 09:43, e-letter wrote: > On 16/11/2012, Rolf Turner <rolf.tur...@xtra.co.nz> wrote: >> >> Your question makes little sense. Functions have derivatives --- at >> least some of them do. Data sets do not have derivatives. The >> functions D(), deriv() etc. work on specified analytic expressions >> for functions --- data sets do not come into the picture. >> > > Is the following procedure correct: > > Plot data from data set. > > Suppose the resultant graph was linear. The function could be y=mx+c, > so the R function 'lm' could be applied to fit a linear line. > > The example in the manual for the help file '?D' shows: > > dx2x <- deriv(~ x^2, "x") ; dx2x > > So for this example it would be correct to write: > > functionname<-deriv(~mx+c,"x");dx2x > > What is the significance of ';dx2x'? It would be appreciated to be > referred to the relevant manual sections, thanks.
Manual "Introduction to R" (http://cran.r-project.org/doc/manuals/r-release/R-intro.html) section 2.1 "Vectors and assignment" in particular the sentence: "If an expression is used as a complete command, the value is printed and lost" Berend ______________________________________________ R-help@r-project.org mailing list 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.
