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...her system not unlike R, mainly because of the >licence price and because I really like R as a tool for almost everything. >But an AD function would really make a huge difference for my work. There are >free tools that can be used to perform AD on C or Fortran code (e.g. >http://www.autodiff.org). One of the difficulties to use them with R is the >need to translate the R code into C of Fortran code, but probably there are >many other problems that I'm not able to see. > >Alberto >-- _____________________________ Hans Julius Skaug Department of Mathematics Univer...

...ot result in the fastest solution, in terms of time taken to calculate the derivatives, but could result in a 'clean' interface that was relatively straightforward to extend. Alternatively, it may be possible to make use of a pre-exisiting AD library in another language (e.g. ADOL-C or the AutoDiff libraries from AD Model Builder). As these libraries are C++ based this would require functions that were written in R to be parsed into C++ and then compiled before their derviatives could be found. Although this has the advantage of using work that is already well developed, the parsing and com...

...could then perhaps tweak some of the core language features if they didn't seamlessly support the AD (we can't do this in Matlab and that is a pain!). My immediate suggestion is that you, or some other more local (to UK) R expert talks at the next European AD workshop in Oxford http://www.autodiff.org/?module=Workshops&submenu=EuroAD/8/main We're a very friendly group and I'm sure there are others who might like to tackle R or perhaps we could put together a multigroup project. If someone could give a talk on R, its language features including the OO aspects, and some optimisatio...

Can someone help me understand the following: > D(expression(dnorm(x, mean)), "mean") [1] 0 > sessionInfo() R version 2.2.1, 2005-12-20, i386-pc-mingw32 attached base packages: [1] "methods" "stats" "graphics" "grDevices" "utils" "datasets" [7] "base" By my computations, this should be