[Haskell-cafe] Why 'round' does not just round numbers ?

Martijn van Steenbergen martijn at van.steenbergen.nl
Mon Oct 27 11:41:36 EDT 2008


Ketil Malde wrote:
> Of course, Haskell should discard the rather tasteless IEEE754 crud,
> and do its calculations on infinite streams of digits.  Then, rounding
> upwards after 'take'ing a sufficient amount of decimals will be the
> right thing to do.

Except arbitrary-precision real arithmetic is not as trivial as you make 
it sound, and using an infinite stream of digits is not sufficient by 
itself.

See also: http://www.haskell.org/haskellwiki/Exact_real_arithmetic

Martijn.


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