Re: Why do some math functions return -0

[KHMan <keinhong@...>]

On 9/20/2010 4:45 AM, HyperHacker wrote:
> [snipped all]
> Note that a number displayed as -0.0000 could also be a  very small
> negative number rounded to fit the display, e.g.:
> > =('%f'):format(-0.00000001)
> -0.000000
> %f rounds to six places by default. This is the proper meaning of
> negative zero - a negative value that rounded to zero.

The last sentence is wrong. No book on computer arithmetic 
discusses a negative zero in such a fashion. Do not mix negative 
zeros with rounding behaviour. It is misleading with respect to 
the standard use of the terminology.

> It'd probably save you a lot of headache in the future to read up on
> how floating-point works, as it has a lot of potential pitfalls.

Ironic.

--
Cheers,
Kein-Hong Man (esq.)
Kuala Lumpur, Malaysia