Add libopenblas-dev to Dockerfile dependencies

[hughjonesd]

This is a requirement for building my Rmlx package, and it seems likely to be useful for many packages. The package is only ~18Kb so unlikely to be too demanding.

[jeroen]

IIRC we did not include it on purpose because it would override or conflict with R's default BLAS implementation and some other R packages had problems icw/ openblas.

Is there a reason Rmlx does not pick up on the default BLAS on the system that is used by all other R packages?

See https://cran.r-project.org/doc/manuals/r-devel/R-exts.html#Numerical-analysis-subroutines-1

Maybe your configure script needs something like

export CPPFLAGS+="$(R RHOME)/include/R_ext"
export LIBS+="(R CMD config BLAS_LIBS)"

[jeroen]

Did this solve your problem?

[hughjonesd]

I worked on the configure script and have something that works with current r-universe – though only on Linux, until MacOS becomes 14.0. It's not quite as simple as picking up the default BLAS, we needed to shim headers, see https://github.com/hughjonesd/Rmlx/blob/master/configure lines 338 and following.

At least, that's what codex told me, and eventually we got something working. It may be that the llm has completely got its knickers in a twist and is missing the obvious way to do it... I must admit that I know nothing about makefiles and configure scripts and am quite deeply interested in not learning about them, so I trust the robot fairly blindly.

Anyway, it seems to work, so I don't think it's necessary to have libopenblas-dev in there, unless it would help others.