[R] double precision
nabble.30.miller_2555 at spamgourmet.com
Wed Aug 19 21:28:13 CEST 2009
Duncan Murdoch-2 wrote:
> I believe the C99 standard doesn't require that a 64 bit signed integer
> type exist (only one that is 64 bits or more), so that would likely
> cause some headaches. And we may still use some compilers that are not
> C99 compliant, which may not have any type that big.
> But an even bigger problem is that there is a lot of type-specific code
> in R. Adding another primitive type like a 64 bit signed integer would
> mean writing arithmetic routines for that type and deciding how it
> interacts with all the other numeric types. For example: what if you
> add a floating point double to a 64 bit int? Normally adding a double
> to an int coerces the result to double. But double isn't big enough to
> hold a 64 bit int exactly. So doing something like x + 1 could lose
> precision in x.
> So I imagine this will happen eventually, but it will not be easy, and
> it probably won't happen soon.
Thanks for the quick response. I have not delved too deeply into the R
source to see how primitives are handled (I can certainly believe adding/
changing would be a significant chore, though). Mostly, I was curious as to
where this fell on the priority schedule. Admittedly, 64-bit integers are
certainly more of a convenience than a necessity. I sincerely appreciate all
the hard work put into a world class project such as this.
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