R-devel: Fortran 90 and note on LAPACK

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 at stats.ox.ac.uk
Emeritus Professor of Applied Statistics, University of Oxford