long integer in R?
On Feb 13, 2010, at 5:04 PM, blue sky wrote:
On Fri, Feb 12, 2010 at 12:06 PM, Simon Urbanek <simon.urbanek at r-project.org> wrote:
On Feb 12, 2010, at 12:33 , blue sky wrote:
R-exts.pdf dosen't list many types that are supported in C++, for example, long. Are there storage.mode corresponds to those extra types?
There are none - that's why they are not listed. As for long: on 32-bit platforms (and Win64) int and long are equivalent so you can simply use INTSXP. On 64-bit unix platforms (LP64) there is no way to losslessly use it (other than raw) but in most applications you can simply use REALSXP as it gives you at least 52-bits of precision which its sufficient for most applications.
According to ?integer, "Note that on *almost* all implementations of R the range of representable integers is restricted to about +/-2*10^9: ?double?s can hold much larger integers exactly." It uses 'almost'. I'm wondering on what platform integer is not restricted to about +/-2*10^9 so that double's can not hold large integers exactly?
I'm not sure I can parse your statement including a question, so I'll rather address the two disjoint parts of the quote: a) restriction of representable integers. Today's platforms use 32-bit integers, but on 16-bit platforms is used to be 16-bit hence the "almost". b) doubles can hold much larger integers exactly (note that there is no "almost" in this part) -- that is what I was saying above since doubles can store 52-bit integers without loss of precision. I hope it helps. Cheers, Simon