[Rd] Lapack / dgesvx function declaration
Prof Brian Ripley
ripley at stats.ox.ac.uk
Fri Jun 6 11:37:14 CEST 2014
On 04/06/2014 10:53, Kristian Buchardt wrote:
> Hello there
> I'm writing some c-code to solve a numerically tough problem for me in
> R. Looking in Lapack.h, i find the following line
> F77_NAME(dgesvx)(const int* fact, const char* trans, const int* n,
> and I believe that "fact" should've been char instead of int, i.e.
> F77_NAME(dgesvx)(const char* fact, const char* trans, const int* n,
> My reasoning: In the R-source:
> I find the following lines:
> * SUBROUTINE DGESVX( FACT, TRANS, N, NRHS, A, LDA, AF, LDAF, IPIV,
> * EQUED, R, C, B, LDB, X, LDX, RCOND, FERR, BERR,
> * WORK, IWORK, INFO )
> * .. Scalar Arguments ..
> * CHARACTER EQUED, FACT, TRANS
> * INTEGER INFO, LDA, LDAF, LDB, LDX, N, NRHS
> * DOUBLE PRECISION RCOND
> where FACT is specified to a char.
> Might this simply be an error in Lapack.h? And can I just edit my
> Lapack.h and compile?
It is an error. Thanks for reporting it: we will change future R
sources and you can edit locally as well.
Note though that passing FORTRAN CHARACTER variables from C is tricky
(see 'Writing R Extensions') and for portable code we would recommend a
FORTRAN wrapper which converted integer codes sent from C to FORTRAN
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
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