Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ames!pacbell!well!nagle
From: nagle@well.UUCP (John Nagle)
Newsgroups: comp.unix.wizards
Subject: Re: what does NaN mean out of printf?
Message-ID: <12831@well.UUCP>
Date: 23 Jul 89 15:04:18 GMT
References: <20283@adm.BRL.MIL> <588@amms4.UUCP> <573@mmlai.UUCP>
Reply-To: nagle@well.UUCP (John Nagle)
Lines: 16


      In IEEE Floating Point, there is a value for the exponent that
indicates that the mantissa, rather than representing a numeric value,
represents a special code.  At least the following codes are defined:

	positive infinity
	negative infinity
	not a number

Uninitialized variables should be initialized to the "not a number"
value, and some implementations do this.  One gets positive infinity
if you divide a positive number by zero, and negative infinity if
you divide a negative number by zero.  Try generating these values 
and see what happens when you print them on your implementation.

					John Nagle