[Rd] calling fortran from C
Prof Brian Ripley
ripley at stats.ox.ac.uk
Thu Oct 20 17:31:48 CEST 2005
On Thu, 20 Oct 2005, James Bullard wrote:
>
> Hello, I had a question about calling some of R's fortran routines from C.
> Specifically, I would like to call: dqrfit from some C code which will be
> bundled as an R package. I was hoping someone knew of an example in some
> of R's code which does something like this (any fortran call from R's C
> would probably be a sufficient guide). So far I can only find locations
> where R calls the Fortran directly, but this is not an option for me.
Look in the lapack module, and also in the stats package for loess (and
others, smooth.spline has both C and Fortran components).
> Also, I am trying to gauge the overhead of making this call, does anyone
> have any knowledge of whether there might be some non-trivial constant
> time penalty on making such a call.
Not significant (and C to Fortran is normally no different from C to C).
In this case you will be calling from a DLL either into an executable or a
DLL and that will be slower than calling within a DLL, how much depending
on the platform.
--
Brian D. Ripley, ripley at stats.ox.ac.uk
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
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