BTW, this has come up several times before, e.g. http://tolstoy.newcastle.edu.au/R/e2/help/07/08/22447.html
is a call for patches. On Mon, 15 Oct 2007, Prof Brian Ripley wrote: > On Mon, 15 Oct 2007, Thomas Yee wrote: > >> Hello, >> >> I was wondering if the functions deriv3(), deriv() etc. could be extended >> to handle psigamma() and its special cases (digamma(), trigamma() >> etc.). From the error message it seems that 'psigamma' needs to be >> added to the derivatives table. >> This might be easy since psigamma() has a deriv argument. > > If you look at ?deriv you will see that it only knows about functions *of > one argument* and operators. So it would be easy to add digamma(x) and > psigamma(x) (and I will do so shortly), it would not be so easy to add > psigamma(x, deriv). I've now implemented that in R-devel, including the 'not so easy' case. >> Additionally, this error message is also obtained when requesting for >> the Hessian of the gamma and lgamma functions: >> >> d3 = deriv(~ gamma(y), namev="y", hessian= TRUE) >> d3 = deriv(~ lgamma(y), namev="y", hessian= TRUE) >> >> Another class of special functions worth adding are the Bessel functions. > > Well, you can always submit a patch .... > > Note that deriv() in R differs from that in S in being done in C and hence > not being user-extensible. A long time ago that had an advantage: S's > deriv could be very slow and take a lot of memory by the standards of the > early 1990's. Rather than work on adding yet more special cases it would > seem better to work on making it user-extensible. > > -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
