Wish List: Extensions to the derivatives table
Hi. Unless I'm misremembering, log, exp, sin, cos, and tan are all handled in deriv3. The functions listed are specially coded slightly more accurate versions but can be substituted with native ones for which deriv/deriv3 will work automatically. I believe that if you write your functions using log(a + 1) instead of log1p(a) or log(x) / log(2) instead of log2(x) deriv3 will work fine. Thanks, Avi
On Fri, Feb 17, 2017 at 2:02 PM Jerry Lewis <jerry.lewis at biogen.com> wrote:
The derivative table resides in the function D. In S+ that table is
extensible because it is written in the S language. R is faster but less
flexible, since that table is programmed in C. It would be useful if R
provided a mechanism for extending the derivative table, or barring that,
provided a broader table. Currently unsupported mathematical functions of
one argument include expm1, log1p, log2, log10, cospi, sinpi, and tanpi.
While manual differentiation of these proposed additions is
straight-forward, their absence complicates what otherwise could be much
simpler, such as using deriv() or deriv3() to generate functions, for
example to use as an nls model.
Thanks,
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