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Path: utzoo!utgpu!water!watnot!watmath!clyde!rutgers!husc6!linus!philabs!pwa-b!mmintl!franka
From: franka@mmintl.UUCP
Newsgroups: comp.lang.c
Subject: Re: Floating Point Comparisons
Message-ID: <2074@mmintl.UUCP>
Date: Wed, 1-Apr-87 17:57:44 EST
Article-I.D.: mmintl.2074
Posted: Wed Apr  1 17:57:44 1987
Date-Received: Sun, 5-Apr-87 10:16:57 EST
References: <842@vaxb.calgary.UUCP>
Reply-To: franka@mmintl.UUCP (Frank Adams)
Distribution: na
Organization: Multimate International, E. Hartford, CT
Lines: 18

In article <842@vaxb.calgary.UUCP> lomow@calgary.UUCP writes:
>While it is clear that comparing floating point numbers using the ==
>  relation is dangerous, are there similar problems with using the
>  other relational operators such as <, <=, >, >=    ?

Only in cases involving near-equality.  For example, don't write:

double a;

for (a = 0.0; a < 1.0; a += 0.1)
	...

because you don't know what will happen the 11th time through.  A good
general rule is: don't make comparisons between floats where you care
which result is returned when the numbers are very close.

Frank Adams                           ihnp4!philabs!pwa-b!mmintl!franka
Ashton-Tate          52 Oakland Ave North         E. Hartford, CT 06108