From:	Mbaccar AT aol DOT com
Message-ID:	<40af648d.2481dc42@aol.com>
Date:	Sat, 29 May 1999 20:11:46 EDT
Subject:	Re: how to round fp-numbers correctly ?
To:	djgpp AT delorie DOT com
CC:	Mbaccar AT aol DOT com
MIME-Version:	1.0
X-Mailer:	AOL 4.0 for Windows sub 11
Reply-To:	djgpp AT delorie DOT com

In a message dated 5/29/99 7:03:52 PM EST, klaas AT ns DOT sympatico DOT ca writes:

> How about:
>  #define ROUND(x) ((x) + SGN(x)*0.5)

Looks good to me. Probably what you could do also is
sgn(x) * ((int) fabs(x) + 0.5)

The reason is simple. There is a discontinuity about 0.
0.6 -> 1
0.6-1 = -0.4 -> -1 using your rule (or my previous which is the same)

so now the delta between the integer numbers of 0.6 and -0.4 is 2
which seems incorrect considering the true delta is 1.0. This is what
you need to watch for in any case.

- Raw text -