On 24/03/2010 1:29 PM, jferr...@umces.edu wrote:
Hi All,
I'm writing R code that would benefit from doing certain tasks using
compiled blocks of code, specifically Fortran subroutines of my own
(already written, debugged in both Fortran77 and Fortran90).
I am currently working on a Windows machine using Lahey and/or MinGW(g77)
compilers.
It is possible to dynamically load Fortran DLLs into R as evidenced from
the several documents I've found on-line giving details on how to do this
(specifically for Windows). However, following the examples in these
documents... none of them successfully deliver a DLL that can be called
from R (and I'm talking for simple test Fortran subroutines that add 2+2).
Either the directions for creating the DLL (for a specific compiler) do
not work (no DLL created), or a DLL is created and exists but will not be
loaded/recognized by R (result of is.loaded = FALSE).
Can anyone give me a quick/dirty step by step on how to create a DLL
(using g77 compiler, specifically MinGW for Windows) so that it will work
in R, on a Windows machine (as well as any tips on anything that has to be
done to, or in, R to get it to work), or if there's a definitive easy to
read paper/book describing the process?
Here's a very simple example using MinGW. The source code in test.f:
subroutine testfun(x, y, z)
real*8 x, y, z
z = x + y
return
end
Compile it using
Rcmd SHLIB test.f
which automatically executes
gfortran -O3 -c test.f -o test.o
gcc -shared -s -static-libgcc -o test.dll tmp.def test.o -lgfortran
-Lf:/R/svn/r-devel/R/bin -lR
(Paths will be different for you.)
Then, in R,
> dyn.load("test.dll")
> is.loaded("testfun")
[1] TRUE
> .Fortran("testfun", x=as.numeric(2), y=as.numeric(2), z=as.numeric(0))
$x
[1] 2
$y
[1] 2
$z
[1] 4
Duncan Murdoch
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