Path: utzoo!utgpu!watmath!att!tut.cis.ohio-state.edu!purdue!ames!apple!motcsd!hpda!hpcuhb!hpcllla!hpclisp!hpclwjm!walter
From: walter@hpclwjm.HP.COM (Walter Murray)
Newsgroups: comp.lang.c
Subject: Re: floating point constants
Message-ID: <660048@hpclwjm.HP.COM>
Date: 27 Jul 89 19:13:38 GMT
References: <1925@arisia.Xerox.COM>
Organization: Hewlett-Packard Calif. Language Lab
Lines: 25

>Is this a valid C program?  gcc 1.35 handles it fine on a sun386i --
>everything else I've tried won't compile these odd constants.

>/* This should print out
>        inf
>        -inf
>        NaN
>*/
>
>main()
>{
>        printf("%f\n", 1.0/0.0);
>        printf("%f\n", -1.0/0.0);
>        printf("%f\n", 0.0/0.0);
>}

In our compiler (HP 9000 Series 800) we evaluate these expressions
at compile time, produce a warning, and store the appropriate
bit patterns for +/- infinity and NaN.  That seemed to be the thing
to do to conform with the spirit of IEEE 754.  Note, however, that
there is no standard for what these numbers look like when formatted
with "%f".

Walter Murray
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