LOGICAL arguments in FORTRAN code

G'day all,

I just took over maintenance of the quadprog package from Kurt Hornik
and noticed that one of the FORTRAN routines has an argument that is
declared to be a LOGICAL.  The R code that calls this routine (via
the .Fortran interface) passes the argument down wrapped in a call to
as.logical().

This was fine (and as documented) under S-Plus 3.4, for which this code
was originally developed.  However, as far as I know, in R objects of
storage mode logical were always supposed to be passed to FORTRAN
arguments of type INTEGER; and that is what the current "Writing R
extension manual states".

Thus, given that the port of quadprog existed for quite some time, I
am wondering whether it is o.k. to pass R objects with storage mode
logical into FORTRAN code to arguments declared as LOGICAL?  Or should
the FORTRAN code be corrected to declare the argument in question as
INTEGER?
The second to be safe.  This is not a question on the S-PLUS/R side 
but on the Fortran side.  A Fortran compiler may or may not use the 
same storage for integer and logical (and it may depend on compiler 
flags, although not on the compilers I just checked, gfortran and 
SunStudio f95).  S-PLUS ran on only a few platforms and with specified 
compilers.
Cheers,

	Berwin

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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)
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Oxford OX1 3TG, UK                Fax:  +44 1865 272595

LOGICAL arguments in FORTRAN code

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