[Rd] R Lapack – why a subset?

[Baptiste Auguie]

Hi,

Why doesn't R include a full Lapack but only a subset?

My cda package (now archived) relying on RcppArmadillo has broken multiple
times on CRAN over the past few years following updates in the underlying
Armadillo library, Every time it follows the same pattern: Armadillo adds a
function to solve a specialised linear system more efficiently, and the
corresponding Lapack routine is not included in the R Lapack subset used on
CRAN, causing breakage. The workaround so far has been an unhappy
compromise with Armadillo developers, adding a "crippled lapack" flag in
the RcppArmadillo configure script, that triggers the use of alternative
(suboptimal) routines and passes CRAN checks. Most RcppArmadillo-dependent
packages don't see the problem; mine seems to be the only one using complex
linear algebra. Two years ago a large number of Lapack routines were added*
to R, and this nicely solved the issue for a while. Unfortunately the same
problem resurfaced last year, with another missing Lapack routine, and my
package is now archived (though it works fine with an external Lapack).
More generally, this workaround is not satisfying for various reasons, and
so I want to ask: why does R ship only a subset of Lapack in the first
place?

Best regards,

baptiste

* Relevant commit at
https://github.com/wch/r-source/commit/98acd96f22eb795a933879c0d3f740e802855473

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