[Rd] R Lapack – why a subset?

[Keith O'Hara]

Peter, 

Is there not already a significant maintenance burden from cherry-picking routines? From my own experience (https://bugs.r-project.org/bugzilla/show_bug.cgi?id=16482 <https://bugs.r-project.org/bugzilla/show_bug.cgi?id=16482>) this is a painful process. And while users may not call these complex routines directly, R is often used as a front-end for libraries that do, so Rlapack-related linking errors are arising more and more.

Is the cost really so high as to preclude adding the remaining Lapack routines to Rlapack? 

Best,
Keith

> On Mar 26, 2018, at 10:24 AM, Peter Dalgaard via R-devel <r-devel at r-project.org> wrote:
> 
> I'm not too happy with this either, but I believe the reason is that there would be a significant extra maintenance burden consisting of things that is not being used by R itself. In particular, complex math routines are little used and have historically caused a number of issues with correct argument and return-value passing. 
> 
> Notice that it is a bit of a can of worms involving matching up C and Fortran compilers, OS versions, routines being and not being present in current LAPACK, which may differ from the system-supplied one, etc.
> 
> -pd
> 
>> On 26 Mar 2018, at 07:49 , Baptiste Auguie <baptiste.auguie at gmail.com> wrote:
>> 
>> 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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>> 
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> 
> -- 
> Peter Dalgaard, Professor,
> Center for Statistics, Copenhagen Business School
> Solbjerg Plads 3, 2000 Frederiksberg, Denmark
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> 
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