[R] .Fortran()

[Prof Brian Ripley]

On Tue, 9 Oct 2001, John Bjornar Bremnes wrote:

> Prof Brian Ripley wrote:
> >
> > On Tue, 9 Oct 2001, John Bjornar Bremnes wrote:
> >
> > > Prof Brian Ripley wrote:
> > > >
> > > > On Mon, 8 Oct 2001, John Bjornar Bremnes wrote:
> > > >
> > > > > I am trying to call some Fortran subroutines using .Fortran(). These
> > > > > subroutines have arguments of type 'character', 'real', 'integer', and
> > > > > 'integer*2'. Is it impossible to call  subroutines expecting both
> > > > > 'character' and 'real' as input?
> > > >
> > > > No, but it is impossible to call those expecting 'integer*2'
> > >
> > > Ok, it seems that I can easily avoid using 'integer*2'
> > >
> > > > See ?.Foreign for what is supported, and note the comments there about
> > > > character types: they work on some compilers and not on others.
> > >
> > > Is g77 one of those where it does not work? I use R-1.3.0 on linux (PC).
> >
> > A properly working version of g77 should work on some platforms (including
> > Linux), but not others (including Windows).
> >
> > > I have tried the following simple example:
> > >
> > >       subroutine mysub(filein, m, x, n)
> > > c
> > >       integer        m, n, i
> > >       character*255  filein
> > >       real           x(n)
> > > c
> > >       write(6,*) 'file: ', filein(1:m)
> > >       do i=1,n
> > >          x(i) = sqrt(1.0*i)
> > >       enddo
> > >       end
> > >
> > > % R CMD SHLIB mysub.f 
> > > g77   -fPIC  -g -O2 -c mysub.f -o mysub.o
> > > gcc -shared  -o mysub.so mysub.o -L/usr/local/lib -lg2c -lm
> > > -L/usr/local/lib -L. -L/usr/lib/gcc-lib/i386-linux/2.95.2 -lm
> > >
> > > > dyn.load("mysub.so")
> > > > .Fortran( "mysub", as.character("myfile"), as.integer(6), as.single(rep(0,10)), as.integer(10), DUP=T )
> > >  file: myfile
> > > Segmentation fault (core dumped)
> >
> > That works for me (RH6.2, gcc 3.0.1, R 1.3.1).
> >  file: myfile
> > [[1]]
> > [1] "myfile"
> >
> > [[2]]
> > [1] 6
> >
> > [[3]]
> >  [1] 1.000000 1.414214 1.732051 2.000000 2.236068 2.449490 2.645751 2.828427
> >  [9] 3.000000 3.162278
> > attr(,"Csingle")
> > [1] TRUE
> >
> > [[4]]
> > [1] 10
> >
> > BTW, no one said Fortran I/O would work, and it sometimes is a problem.
> >
> > > % R
> > > > dyn.load("mysub.so")
> > > > .Fortran( "mysub", as.character("myfile"), as.integer(6), as.single(rep(0,10)), as.integer(10), DUP=F )
> > > Error: character variables must be duplicated in .C/.Fortran
> >
> > > Any comments?
> >
> > Do you have one of the many broken Linux versions of g77?
> >
>
> I have now tried versions 2.95.2 and 3.0 with no success. I will ask my
> system administrator to install the latest gcc version (3.0.1?). Maybe I
> should update R to 1.3.1 also. BTW where is the default compiler options
> set for 'R CMD SHLIB'?

>From the configure script, in etc/Makeconf.

I doubt if 3.0.1 would help much over 3.0.  It's puzzling though.

> In
> "Writing R Extensions" on page 23 it says "It is not possible to pass
> numeric vectors as float * or REAL if DUP=TRUE". It should be DUP=FALSE,
> or?

It should be FALSE, and I've jut fixed it, thanks.

>
>
> John Bjornar Bremnes
> Norwegian Meteorological Institute
>

-- 
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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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