Re: Why do some math functions return -0

[Tony Finch <dot@...>]

On 21 Sep 2010, at 02:35, Mike Pall <mikelu-1009@mike.de> wrote:
> 
> Also note that your finding is unrelated to the problem at hand
> (no constant folding, no change of rounding mode). There's some
> prior evidence of buggy or miscompiled floor/ceil for OSX/PPC:
> 

That explains it :-) I was wrong to blame rounding in general, but that was the only explanation I could think of late at night for subtraction giving -0 in the default rounding mode (nearest). Inconsistent constant folding effects are a red herring too because they don't explain the weird behaviour of Lua (where compile time constants aren't involved) but broken floor() does explain that.

Tony.
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