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

Janis Voigtlaender voigt at tcs.inf.tu-dresden.de
Mon Oct 27 06:37:55 EDT 2008

Henning Thielemann wrote:
> 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 repeated rounding *is* worse than rounding in one go, under any
reasonable scheme:

3.46 -> 3.5 -> 4


3.46 -> 3

That was actually the debate with that teacher. Unbelievable as that
still is to me today, she advocated the 3.46 -> 3.5 -> 4 route...

And yes, Henning, you are right, we didn't yet share school in fourth
grade when rounding was taught.

Ciao, Janis.

Dr. Janis Voigtlaender
mailto:voigt at tcs.inf.tu-dresden.de

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