On 16/11/12 02:40, e-letter wrote:
Readers,
A data set comprises
A B C
10 6 .2
20 7 .4
30 8 .16
40 9 .0256
My requirement is to obtain the derivative for values of A with
respect to B, create a function in R and plot this derivative against
another variable (e.g. values in column C).
Have searched the mailing list and found reference to a function 'D',
but the help accessed via '?D' and '?deriv' does not explain how to
write a derivative function.
Could someone please direct me to the relevant parts of the manual to begin?
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.
What you might possibly want to do is to fit a spline to your data
and take the derivative of the spline. The function splinefun()
could be what you need.
cheers,
Rolf Turner
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