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
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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.