[R] precision in seq

Barry Rowlingson b.rowlingson at lancaster.ac.uk
Tue Feb 5 11:41:05 CET 2008


Prof Brian Ripley wrote:
> FAQ Q7.31 and ?"==" should enlighten you.
> 
> None of 0.05, 0.1 ... 0.9, 0.95 are exactly representable on a binary 
> computer.

  Doesn't the string "0.95" constitute an exact representation? And my 
computer is definitely binary. Although I suspect it is also bipolar.

  It's the lack of understanding of the underlying encoding of real 
numbers - or even the actual *existence* of the underlying encoding - 
that means the cry of 'FAQ Q7.31!' will long echo down the halls of R-help.


Barry



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