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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