I'm not one of the implementors, but this sort of behavior
can reduce error in fields where X.5 is a common result-
a rule like "The nearest even integer" moves upward half
the time and downward half the time- hopefully cancelling
itself out.
Or maybe they had other reasons...
Joe
> -----Original Message-----
> From: Rijk-Jan van Haaften [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, May 09, 2001 8:06 AM
> To: [EMAIL PROTECTED]
> Subject: Class RealFrac: round
>
>
> Hello,
>
> While I were writing a RealFrac implementation for BigDouble's (for
> high-precision computations) I found a strange implementation of
> round in the standard prelude (from the haskell definition):
...
> The strange case is if signum (abs r - 0.5) is 0:
> such numbers are round to the nearest EVEN integer. In mathematics,
> computer science (the studies I'm doing) and physics, as far as I
> know, it is usual to round such numbers up, rather than to the nearest
> integer. For example:
>
> Number Hugs Math
> 0.5 0 1
> 1.5 2 2
> -3.5 -4 -4
> 6.5 6 7
>
> Why did the Haskell designers choose this behaviour?
>
> Thanks in advance,
>
> Rijk-Jan van Haaften
>
>
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