On 12-Feb-08 14:53:19, Gavin Simpson wrote: > On Tue, 2008-02-12 at 15:35 +0100, [EMAIL PROTECTED] wrote: >> Dear developer, >> >> in my version of R (2.4.0) as weel as in a more recent version >> (2.6.0) on different computers, we found this problem : > > No problem in R. This is the FAQ of all FAQs (Type III SS is > probably up there as well).
I'm thinking (by now quite strongly) that there is a place in "Introduction to R" (and maybe other basic documentation) for an account of arithmetic precision in R (and in digital computation generally). A section "Arithmetic Precision in R" near the beginning would alert people to this issue (there is nothing about it in "Introduction to R", "R Language Definition", or "R internals"). Once upon a time, poeple who did arithmetic knew about this from hands-on experience (just when do you break out of the loop when you are dividing 1 by 3 on a sheet of paper?) -- but now people press buttons on black boxes, and when they find that 1/3 calculated in two "mathematically equivalent" ways comes out with two different values, they believe that there is a bug in the software. It would not occur to them, spontaneously, that the computer is doing the right thing and that they should look in a FAQ for an explanation of how they do not understand! I would be willing to contribute to such an explanation; and probably many others would too. But I feel it should be coordinated by people who are experts in the internals of how R handles such things. Best wishes to all, Ted. -------------------------------------------------------------------- E-Mail: (Ted Harding) <[EMAIL PROTECTED]> Fax-to-email: +44 (0)870 094 0861 Date: 12-Feb-08 Time: 15:31:26 ------------------------------ XFMail ------------------------------ ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
