On 2012-11-16 01:30, Berend Hasselman wrote:
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
I believe that e-letter is confused by the space-saving
use of the semicolon to place two R expressions on one line.
He neither needs nor wants the ';dx2dx' in his own
expressions.
Peter Ehlers
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