[REBOL] Re: mathematical rounding...
From: rpgwriter::yahoo::com at: 6-Nov-2001 14:47
--- Gregg Irwin <[greggirwin--mindspring--com]> wrote:
> Hi Alan,
>
> << There are several accepted methods of rounding.
> One version for rounding
> from 0.5 says to round up if the number to the left
> of the decimal is even,
> and truncate if it is odd. The purpose (hope) is to
> randomize the error
> so any statistics behave better. >>
>
> Right. That's what I meant by statistical rounding.
Right. Other schemes try to preserve different
features.
Examples
Round even (or odd) guarantees that:
1) if integer-parts are evenly distributed, rounding
bias cancels.
2) round(-x) equals -round(x)
Round toward (or away from) zero guarantees that:
1) round(-x) equals -round(x)
2) if (sign(x)=sign(x+1)) round(x)+1 = round(x+1)
Round greater (or less) guarantees that:
1) round(x)+1 = round(x+1)
This isn't exhaustive, merely illustrative. In
different applications, different behaviors may be
most desirable.
