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From: manis@ubc-cs.UUCP
Newsgroups: comp.lang.c
Subject: Re:  float ==
Message-ID: <949@ubc-cs.UUCP>
Date: Tue, 31-Mar-87 11:04:31 EST
Article-I.D.: ubc-cs.949
Posted: Tue Mar 31 11:04:31 1987
Date-Received: Sat, 4-Apr-87 04:43:23 EST
References: <6529@brl-adm.ARPA>
Reply-To: manis@ubc-cs.UUCP (Vincent Manis)
Organization: UBC Department of Computer Science
Lines: 17

In article <6529@brl-adm.ARPA> gwyn@BRL.ARPA (VLD/VMB) writes:
>I don't think at this stage X3J11 would really take my idea about
>banishing floating == very seriously.  It may very well be something
>that "lint" should catch, though.

Back in prehistory (about 1970) I used a Fortran compiler on a Univac 1108
running the Exec 2 operating system. This compiler would generate a warning
when you compared floating point numbers for equality (or non-equality). I
would go further than asking lint to catch it. This is a classic instance of
something the compiler knows and can easily tell you. A non-fatal warning
(which can be suppressed) is all that's really necessary. Something like
"Warning: floating point equality tests are rarely correct" would do quite
nicely. A compiler which generates this warning is only trivially
non-compliant. 

A "flequal(a, b, fuzz)" function is a perfect candidate for a library
routine (or even an inline expansion).