[fpc-devel] format function

[Christian Ulrich]

when the statement

if (-0 = 0)

is true then RoundTo schould not return an numer like -0 ?!
i think the point of view of an fpu is in the round functions not nessesary 
0 is 0 and not -0



----- Original Message ----- 
From: "Jonas Maebe" <jonas.maebe at elis.ugent.be>
To: "FPC developers' list" <fpc-devel at lists.freepascal.org>
Sent: Thursday, October 12, 2006 3:46 PM
Subject: Re: Re[2]: [fpc-devel] format function



On 12 okt 2006, at 15:41, Пётр Косаревский wrote:

> In the othe case, if the user is supposed to understand, that he  looks at 
> some representation of binary representation of a real  number, "-0.000" 
> obviously means "little negative number".

No, it means the value 0, but with a negative sign. The value "-0" is
representable in an exact way on any IEEE standard-compliant fpu. The
reason is that fpu's have a separate bit to store the sign. So even
if the mantissa and exponent show that it's the value zero, the sign
bit can still be one (meaning that it's a negative zero). And for
some fpu calculations this even matters.


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