Henning Thielemann wrote:
On Mon, 27 Oct 2008, L.Guo wrote:
I think this is unresonable. then try it in GHC 6.8.3.
Prelude> round 3.5
4
Prelude> round 2.5
2
Is there any explanation about that ?
It's the definition we learnt in school ...
Hmm, Henning, this is strange. The two of us went to the very same
school, but I know for a fact that I learnt 2.5 to round to 3, not 2 as
above. ;-)
I think one reason is that repeated rounding should not be worse than
rounding in one go. Consider the rule 'use ceiling when the first
removed digit is 5'. Then
0.45 - (round to one place) -> 0.5 - (round to integer) -> 1
but
0.45 - (round to integer) -> 0
That is of course true (and was the topic of heated discussion with my
fourth grade math teacher), but does not explain 2.5 -> 2.
Ciao, Janis.
--
Dr. Janis Voigtlaender
http://wwwtcs.inf.tu-dresden.de/~voigt/
mailto:[EMAIL PROTECTED]
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