Re: [Rd] [R] Use of .Fortran

From: Prof Brian Ripley <ripley_at_stats.ox.ac.uk>
Date: Fri, 18 Jun 2010 16:06:20 +0100 (BST)

On Sat, 19 Jun 2010, David Scott wrote:

> I have no experience with incorporating Fortran code and am probably doing
> something pretty stupid.

Surely you saw in the posting guide that R-help is not the place for questions about C, C++, Fortran code? Diverting to R-devel.

> I want to use the following Fortran subroutine (not written by me) in the

Well, it is not Fortran 77 but Fortran 95, and so needs to be given a .f95 extension to be sure to work.

> file SSFcoef.f
>
> subroutine SSFcoef(nmax,nu,A,nrowA,ncolA)
> implicit double precision(a-h,o-z)
> implicit integer (i-n)
> integer l,i,nmax
> double precision nu,A(0:nmax,0:nmax)
> A(0,0) = 1D0
> do l=1,nmax
> do i=1,l-1
> A(l,i) = (-nu+i+l-1D0)*A(l-1,i)+A(l-1,i-1)
> end do
> A(l,0) = (-nu+l-1D0)*A(l-1,0)
> A(l,l) = 1D0
> end do
> return
> end
>
>
> I created a dll (this is windows) using R CMD SHLIB SSFcoef.f
>
> Then my R code is:
>
> ### Load the compiled shared library in.
> dyn.load("SSFcoef.dll")
>
> ### Write a function that calls the Fortran subroutine
> SSFcoef <- function(nmax, nu){
> .Fortran("SSFcoef",
> as.integer(nmax),
> as.integer(nu)
> )$A
> }

That does not match. nrowA and ncolA are unused, so you need SSFcoef <- function(nmax, nu){

   .Fortran("SSFcoef",

            as.integer(nmax),
            as.integer(nu),
            A = matrix(0, nmax+1, nmax+1),
            0L, 0L)$A

}

>
> SSFcoef(10,2)
>
> which when run gives
>
>> SSFcoef(10,2)
> NULL
>
> I am pretty sure the problem is that I am not dealing with the matrix A
> properly. I also tried this on linux and got a segfault.
>
> Can anyone supply the appropriate modification to my call (and possibly to
> the subroutine) to make this work?
>
> David Scott

>
>
> --
> _________________________________________________________________
> David Scott Department of Statistics
> The University of Auckland, PB 92019
> Auckland 1142, NEW ZEALAND
> Phone: +64 9 923 5055, or +64 9 373 7599 ext 85055
> Email: d.scott_at_auckland.ac.nz, Fax: +64 9 373 7018
>
> Director of Consulting, Department of Statistics
>
> ______________________________________________
> R-help_at_r-project.org mailing list
>
https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

-- 
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 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

______________________________________________
R-devel_at_r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
Received on Fri 18 Jun 2010 - 15:14:08 GMT

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.2.0, at Sun 20 Jun 2010 - 10:11:06 GMT.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-devel. Please read the posting guide before posting to the list.

list of date sections of archive