[R-pkg-devel] Use of long double in configuration

[Simon Urbanek]

Tim,

no, and as far as I can tell some of the claims in that thread are incorrect. Whether long double is identical to double is irrelevant and has nothing to do with it.

R has a configuration option --enable-long-double which governs whether R should use algorithms which can benefit from extended precision where applicable. However, that is entirely internal to R and has nothing to do with packages, it just changes algorithms used in R itself.

It is definitely a bug in matrixStats to assume that HAVE_LONG_DOUBLE  of LDOUBLE are somehow defined as they are not unless matrixStats does so.

Cheers,
Simon



> On Apr 30, 2025, at 8:25 PM, Tim Taylor <tim.taylor using hiddenelephants.co.uk> wrote:
> 
> Is it correct to say that R's conditional use of long double is around ensuring things work on platforms which have 'long double' identical to 'double' types, as opposed to there being an odd compiler targeted that does not even have any concept of 'long double' type?
> 
> As background this was motivated by a query raised in the matrixStats package:
> https://github.com/HenrikBengtsson/matrixStats/issues/278
> 
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