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Path: utzoo!linus!philabs!seismo!ut-sally!utastro!nather
From: nather@utastro.UUCP (Ed Nather)
Newsgroups: net.arch
Subject: Re: Complement Arithmetic
Message-ID: <49@utastro.UUCP>
Date: Fri, 27-Jan-84 12:20:17 EST
Article-I.D.: utastro.49
Posted: Fri Jan 27 12:20:17 1984
Date-Received: Sat, 28-Jan-84 02:54:38 EST
References: <1425@burdvax.UUCP>
Organization: UTexas Astronomy Dept., Austin, Texas
Lines: 11

<>
There's a famous shin-barking problem in astronomy that ones complement
arithmetic can fix.  We still use the Babylonian designation for angles
as degrees, minutes, and seconds for the declination direction (pole to
pole) and things go very funny for declinations near the equator, where
the values come out like  "0 degrees,  12 minutes,  24 seconds, usually
written as "00 12 24".  This one is OK, but how about "-00 12 24"?  The
programmer must propagate the minus sign to the integers 12 and 24, and
any testing must test all three before the sign of the result is chosen.

The problem would be much simplified if we could test for neagtive zero!