[R] Calling Fortran from R: Issues with dynamic loading of fortran dll

[Duncan Murdoch]

On 16/01/2012 8:55 AM, David Stevens wrote:
> I installed RTools - though I'm unable to use it within R, from the
> command prompt the file will compile and create the foo.dll using R CMD
> SHLIB foo.f.  I simlified to code for fortran IV (?really) compliance
>
> foo.f:
>
>          Subroutine foo(x)
>          real x
>          x = x + 2.
>          return
>          end
>
> R CMD SHLIB foo.f
> cygwin warning:
>     MS-DOS style path detected: d:/PROGRA~1/r/R-214~1.1/etc/i386/Makeconf
>     Preferred POSIX equivalent is:
> /cygdrive/d/PROGRA~1/r/R-214~1.1/etc/i386/Makeconf
>     CYGWIN environment variable option "nodosfilewarning" turns off this
> warning.
>     Consult the user's guide for more details about POSIX paths:
>       http://cygwin.com/cygwin-ug-net/using.html#using-pathnames
> gfortran      -O3  -mtune=core2 -c foo.f -o foo.o
> gcc -shared -s -static-libgcc -o foo.dll tmp.def foo.o
> -Ld:/RCompile/CRANpkg/extralibs/local/lib/i386
> -Ld:/RCompile/CRANpkg/extralibs/local/lib -lgfortran
> -Ld:/PROGRA~1/r/R-214~1.1/bin/i386 -lR
>
> Now the issue is getting it to dyn.load("foo.dll"). I'm greeted with
>
> Error in inDL(x, as.logical(local), as.logical(now), ...) :
>     unable to load shared object 'd:/Fortran folders/Fortran
> Multiresponse/foo.dll':
>     LoadLibrary failure:  %1 is not a valid Win32 application.
>
> Any thoughts?

It worked for me.  That is,  I created the foo.f file, then ran

R CMD SHLIB foo.f

from the command line, then rgui on the command line.  Once in R I ran

dyn.load("foo.dll")

and it worked without a complaint on my system.  I would guess the 
differences are:

1.  I have the stupid "nodosfilewarning" set to keep Cygwin programs quiet:

set CYGWIN=nodosfilewarning

2.  I ran rgui from the command line.  That means I got it from the same 
path where R was found in the R CMD SHLIB call.  You might have run a 
different version, or might have been in a different directory, trying 
to load some other "foo.dll" if you started rgui in some other way.

Duncan Murdoch

> David S
>
> On 1/15/2012 5:09 PM, Duncan Murdoch wrote:
> >  On 12-01-15 5:34 PM, David Stevens wrote:
> >>  I successfully used .Fortran to load and execute my fortran procedures
> >>  under WinXP and 32 bit R. Alas, the same isn't true with my next Windows
> >>  7/64 machine, R 2.14.1 (64 bit) and the gnu gfortran (64) compiler
> >>  (mingw64 v. 4.6.1). Though I'm able to compile the routines from the
> >>  command line using gfortran '...', .Fortran('foo2') results in an error
> >>  saying the Fortran symbol name "foo2" not in load table.
> >>
> >>  foo.f90:
> >>
> >>  Module foo
> >>  contains
> >>     Subroutine foo2(x)
> >>
> >>       real(kind=8),intent(inout) :: x
> >>       x = x + 2
> >>
> >>  end subroutine foo2
> >>
> >>  end module foo
> >>
> >>  c:\mingw64\bin\gfortran --shared -Wall -pedantic -g -o foo.dll foo.f90
> >>
> >>  ff = "d:/Fortran folders/Fortran Multiresponse/foo.dll"
> >>  x= dyn.load(ff)
> >>  .Fortran('foo2',as.double(1))
> >>
> >>  Error in .Fortran("foo", as.double(1)) :
> >>      Fortran symbol name "foo" not in load table
> >>
> >>  Can someone point me in the direction of a solution?
> >
> >  Some or all of these might help:
> >
> >  1.  Get R to do the compiling for you:  it knows the compiler
> >  arguments that produce compatible code.  (Use R CMD shlib for this.)
> >
> >  2.  Use a compiler supplied with the Rtools collection.
> >
> >  3.  Find out what name got exported, and use .C instead of .Fortran to
> >  call that.
> >
> >  Duncan Murdoch
>