[R] R Base Code

[Ben Bolker]

nancy_shackelford <nancy.shackelford <at> gmail.com> writes:

> Hello all,
> 
> I need to imitate the 'q' function (qnorm, qweibull, etc) for Clark's 2Dt
> distribution model.  I'm not skilled enough in R to code it myself, so I
> thought I could find the base code for one of the existing 'q' functions and
> just modify it.  However, I'm having trouble navigating through the R Source
> Code on the CRAN website.  I've searched some forum and help sites, but I
> can't find anything specific on locating function codes.  
> 
> I also read somewhere that Clark's 2Dt is available in the R distribution
> functions, but I haven't found anything that confirms that.  

   You can find the C source code for qt in

http://svn.r-project.org/R/trunk/src/nmath/qt.c

  and the R code is in

http://svn.r-project.org/R/trunk/src/library/stats/R/distn.R

but I don't think this is really what you want.  As pointed out
in Clark et al 1999 (Ecology), the "Clark 2Dt" function is just a bivariate
version of the univariate t-distribution.  I think that if you stare at
the equations in Clark et al 1999 and (e.g.) in ?dt you can probably
adapt the existing pt/qt functions to get where you need, adjusting
normalizing constants as appropriate ...

  PS: when asking questions about field-specific topics on the
general R list, it's a good idea to give a little more background --
even references, in case someone is interested. Few people outside
of community ecology have heard of "Clark's 2Dt" ...

  good luck,
    Ben Bolker