Hi, That is a fairly standard implementation of rounding for financial institutions. Consider sum . map round Over the list [3.5,2.5] With rounding to the nearest even integer for 0.5's you get 6, otherwise if you always round up you get 7. If you bias towards rounding up you get a general upwards trend as numbers are rounded, which is bad, while the even condition ensures that statistically it averages to the same thing. For more details see: http://en.wikipedia.org/wiki/Rounding#Round-to-even_method Thanks Neil
-----Original Message----- From: haskell-cafe-bounces@haskell.org [mailto:haskell-cafe-bounces@haskell.org] On Behalf Of L.Guo Sent: 27 October 2008 9:49 am To: MailList Haskell-Cafe Subject: [Haskell-cafe] Why 'round' does not just round numbers ?
Hi all:
I just read about definitions of Prelude [1], and noticing that.
In 6.4.6 Coercions and Component Extraction, it discribes like this:
"round x returns the nearest integer to x, the even integer if x is equidistant between two integers."
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 ?
[1] The Haskell 98 Report: Predefined Types and Classes http://haskell.org/onlinereport/basic.html
Regards -------------- L.Guo 2008-10-27
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