R help - Nov 2012 - create function to solve derivative

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?

--
R2151

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