Article View: sci.math.num-analysis
Article #199Why IEEE NaN and Inf?
From: Dan Frankowski
Date: Thu, 06 Aug 1992 14:40
Date: Thu, 06 Aug 1992 14:40
21 lines
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1358 bytes
I know the behavior of Inf and NaN (1/0 = Inf, 0/0 = NaN, etc.) in the
IEEE floating point arithmetic standard. In fact, I have the standard
sitting here in front of me. But what are the reasons they were
implemented? Why Infs? NaNs? Signalling NaNs vs. quiet NaNs?
This is part of my work to understand the effects of adding a complex
type to C. For instance, in general
(x, y) * (u, v) = ( x*u - y*v, y*u + x*v )
So 3.0 * (Inf, 5.0) = (3.0, 0.0) * (Inf, 5.0)
= (3.0*Inf - 0.0*5.0, 0.0*Inf + 3.0*5.0)
= (Inf, NaN)
But there is a reasonable argument to preserve a scaling property of
real numbers and have 3 * (Inf, 5.0) = (Inf, 15.0).
What would be reasonable behaviors of Inf and NaN to preserve with
complex arithmetic?
Dan Frankowski dfrankow@centi.cs.umn.edu
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Path: arc1-ca.pugleaf.net!sparky!uunet!dtix!darwin.sura.net!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!The-Star.honeywell.com!umn.edu!centi!dfrankow From: dfrankow@centi.cs.umn.edu (Dan Frankowski) Newsgroups: sci.math.num-analysis Subject: Why IEEE NaN and Inf? Message-ID: <1992Aug6.144008.20542@news2.cis.umn.edu> Date: 6 Aug 92 14:40:08 GMT Sender: news@news2.cis.umn.edu (Usenet News Administration) Organization: University of Minnesota, Minneapolis, CSci dept. Lines: 21 Nntp-Posting-Host: centi.cs.umn.edu