[Rd] How to call DBLEPR in Fortran code to be used by R

Duncan Murdoch murdoch.duncan at gmail.com
Fri Dec 10 14:19:57 CET 2010

On 09/12/2010 1:11 PM, Marian K Talbert wrote:
> Hi
> I've built a dll using Fortran code and can call it by either R or
> Fortran. Calling by the former gives me the wrong answer and the later
> gives the correct answer.

That sounds like a type problem.  Are you using double precision variables?

>    From what I've read, it looks like I should use
> the subroutines DBLEPR, INTPR and REALPR to get values to show up in R
> which I hope will allow me to find the error.  I've downloaded the
> R-2.12.0.tar.gz but have been unable to find these subroutines or any
> examples of how to get Fortran to recognize them.  Obviously when I try to
> compile I get undefined reference to 'dblepr_'.  So I was wondering if
> there is some way I can specify in the makefile or possibly by building
> the dll using R CMD SHLIB where to find these subroutines or where else
> this information might need to be.  I noticed in Venables book that the
> functionality of these subroutines can be compiler dependent but there is
> no specification of which compilers might work.  I'm using gfortran could
> this be an issue?

You should use

R CMD SHLIB source.f

to compile your Fortran.  Does the example of dblepr in Writing R 
Extensions work for you?

Duncan Murdoch

> Thanks,
> Marian Talbert
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