Path: utzoo!attcan!uunet!husc6!rutgers!bellcore!decvax!spray!anson
From: anson@spray.CalComp.COM (Ed Anson)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Float to integer conversion problem in LSC 3.0?
Keywords: Lightspeed, LSC, conversion
Message-ID: <2403@spray.CalComp.COM>
Date: 8 Aug 88 14:39:33 GMT
References: <5813@batcomputer.tn.cornell.edu>
Reply-To: anson@spray.UUCP (Ed Anson)
Organization: CalComp, A Lockheed Company, Hudson, NH, USA
Lines: 20

In article <5813@batcomputer.tn.cornell.edu> eacj@tcgould.tn.cornell.edu (Julian Vrieslander) writes:
>	
>        m = 126.0;          /* m becomes 126 */	
>        d = 12.6 * 10.0;    /* d becomes 126 */
>        n = d;              /* n becomes 125 !! */
>		
>I cannot understand why n gets "rounded down" to 125.

Because of the differences between binary and decimal notation, the value
12.6 cannot be represented exactly in floating point format.

My guess is that 12.6 gets converted to something just a hair lower than
12.6, which will always give the result described.

When converting from floating point to integer, I generally round the 
value, rather than simply truncate. That approach saves a lot of grief.
-- 
=====================================================================
   Ed Anson,    Calcomp Display Products Division,    Hudson NH 03051
   (603) 885-8712,      anson@elrond.CalComp.COM