[R] R and Fortran in Windows

[Dan Stram]

I just joined the list and appologize if this has been answered before
but I am trying to interface between R and the Compaq Visual Fortran
compiler version 6.6 for Windows. 

I found the following instructions on the web -- and an example.  When I
follow these directions exactly. R 2.0.0 crashes. Has anyone had any
experience with this?

Below are the instructions that I located:

Thanks


Dan Stram

Professor
Department of Preventive Medicine
Division of Genetic Epidemiology and Biostatistics
University of Southern California
1540 Alcazar Street, Suite 220
Los Angeles, CA 90033
tel 323-442-1817
fax 323-442-2349
email stram at usc.edu
web http://www-rcf.usc.edu/~stram





These notes were written by J.R.M. Hosking.

Using Fortran routines from R with CVF

1.  Take a working Fortran subroutine, and put its name in an
ATTRIBUTES DLLEXPORT directive to ensure that the routine name
is exported from the DLL that will be built.  Example:

      SUBROUTINE MYSUB(X,N,XMEAN)
CDEC$ ATTRIBUTES DLLEXPORT :: MYSUB
     IMPLICIT DOUBLE PRECISION (A-H,O-Z)
     DOUBLE PRECISION X(N)
     XMEAN=0D0
     DO 10 J=1,N
     XMEAN=XMEAN+X(J)
  10 CONTINUE
     XMEAN=XMEAN/N
     RETURN
     END

2. Compile and link the routine using the CVF options /assume:underscore
and  /dll.  E.g., supposing that the routine is in a file rtest.f,
at the command prompt type

   df rtest.f /assume:underscore /dll

This will create a file rtest.dll file that should be kept, and
.obj, .lib and .exp files that are not needed for R and can be deleted.
(/assume:underscore is needed because R expects that a routine name
exported from a DLL will have an underscore appended to it, but CVF
does not do this by default.)

3.  Now from an R command prompt, use dyn.load to load the DLL and
.Fortan("MYSUB",...) to call the function.  Example:

  > dyn.load("E:\\rtest.dll")
 > is.loaded(symbol.For("MYSUB"))
 [1] TRUE
 > x<-1:6
 > .Fortran("MYSUB",as.double(x),as.integer(length(x)),xmean=double(1))
 [[1]]
 [1] 1 2 3 4 5 6

  [[2]]
 [1] 6

  $xmean
 [1] 3.5

  >