[Rd] R-devel: Fortran 90 and note on LAPACK

[Prof Brian Ripley]

On 24/03/2022 16:32, Avraham Adler wrote:
> Hello.
> 
> In the current notes for R-devel [1] referring to LAPACK, it states
> 
>> The included LAPACK sources have been updated to version 3.10.0, except for the four Fortran
>> 77 routines which 3.10.0 has re-implemented in Fortran 90 (where the older versions have been
>> retained as the R build process does not support Fortran 90)
> 
> I am a bit confused as I know R supports F9x [2]. Moreover, an F90
> compiler seems to be the minimum requirement for R [3]. May I ask for
> clarification of this note, please?

You are seriously confused.  Reference [2] is about package 
installation, not building R.  As R CMD INSTALL is almost entirely 
written in R, it is necessarily not usable in the early stages of 
building R such as compiling in src/modules/lapack.

We could have added support for .f90 files and Fortran modules to the R 
build, but not in time for R 4.2.0.  The NEWS for R-devel (you linked to 
that for 4.2.0alpha) has further information on future plans.

There are reports of bugs in two of the new LAPACK routines, another 
reason not to use them in R 4.2.0.

> 
> Thank you,
> 
> Avi
> 
> [1]: https://cran.r-project.org/doc/manuals/r-devel/NEWS.html
> [2]: https://cran.r-project.org/doc/manuals/r-release/R-exts.html#Using-F9x-code
> [3]: https://cran.r-project.org/doc/manuals/R-admin.html#Using-Fortran


-- 
Brian D. Ripley,                  ripley using stats.ox.ac.uk
Emeritus Professor of Applied Statistics, University of Oxford