p. 83 'Coercions and Component Extraction'
I find it quite odd that round 3.5 returns 4, but round 2.5 returns 2.
I always thought that round x.5 returns x+1 (instead of the
even integer).
That's the behaviour in most math books and programming languages
It looks odd to me too. I think this is just taken from some other
standard, so I don't propose to alter it.
Can anyone shed light?
This is generally considered the most accurate kind of rounding, since it
avoids cumulative errors. If you get lots of values on the 0.5 boundary,
`round up' gives you an error of +0.5 for each, whereas round-to-even gives
you a mean error of zero.
I think IEEE floating point does this by default for its basic operations.
--KW 8-)
--
: Keith Wansbrough, MSc, BSc(Hons) (Auckland) :
: PhD Student, Computer Laboratory, University of Cambridge, England. :
: (and recently of the University of Glasgow, Scotland. [] ) :
: Native of Antipodean Auckland, New Zealand: 174d47' E, 36d55' S.:
: http://www.cl.cam.ac.uk/users/kw217/ mailto:[EMAIL PROTECTED] :
:-:
--
: Keith Wansbrough, MSc, BSc(Hons) (Auckland) :
: PhD Student, Computer Laboratory, University of Cambridge, England. :
: (and recently of the University of Glasgow, Scotland. [] ) :
: Native of Antipodean Auckland, New Zealand: 174d47' E, 36d55' S.:
: http://www.cl.cam.ac.uk/users/kw217/ mailto:[EMAIL PROTECTED] :
:-:
--
: Keith Wansbrough, MSc, BSc(Hons) (Auckland) :
: PhD Student, Computer Laboratory, University of Cambridge, England. :
: (and recently of the University of Glasgow, Scotland. [] ) :
: Native of Antipodean Auckland, New Zealand: 174d47' E, 36d55' S.:
: http://www.cl.cam.ac.uk/users/kw217/ mailto:[EMAIL PROTECTED] :
:-:
