Hello all,
it seems my efforts in reading the manuals and help files aren't enough
so here I am. The question is, how would I go about linking a
pre-compiled DLL in to my package? I have previously successfully built
packages with Fortran and C source code, but now I'd like to take this
ready made DLL and call its routines from R.
My collegue was brave enough to simply try and put the DLL in src folder
of the package and proceed with building and installing the same way as
if it had been source code. And it works, on my computer and his.
Clearly this isn't exactly portable, and while that's ok for the use we
have in mind (we both work on Windows XP) I have a nagging feeling this
is somehow criminal or unwise at least.
Why I want to do this might explain it a bit further but in fact the
background contains another problem and I welcome anyone to give hints
about that too.
So, we have some Fortran code from way back which deals with fitting
taper curves for tree boles, and some other functions related to that.
We wanted to make these available for use in R and I made a package with
simple wrapper functions for the .Fortran calls, and built it with the
help of the compiler in Rtools. All was fine until my collegue managed
to bump in to a combination of parameters (tree species, height and
breast height diameter) with which the computation freezes. We traced it
to a certain very simple iteration in the Fortran code that finds the
height at which the tree has a given diameter. I could give more details
on that, but the point is that the very same computation goes through
just fine when executed "fully" in Fortran, with the routines and an
interface compiled with another Fortran compiler. And also when that
compiler is used to make a DLL and that DLL is used within the R package
in the way I described above.
In summary, what we seem to have here is a compiler dependent
convergence problem. Possible solutions are to figure out what's wrong
with the computation - and I've pretty much exhausted my skills on that
- or to figure out how to use a working DLL, as was my first question.
Great big thanks in advance to anyone with advice!
Seija Sirkiä,
senior researcher (statistics), Finnish forestry research institute
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