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Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!think!snorkelwacker!spdcc!ima!haddock!karl
From: karl@haddock.ima.isc.com (Karl Heuer)
Newsgroups: comp.theory,comp.misc,comp.lang.misc,comp.arch
Subject: Re: Modulus (Re: hashing function for strings)
Summary: why do we use sign-magnitude representation?
Message-ID: <16014@haddock.ima.isc.com>
Date: 23 Feb 90 21:35:51 GMT
References: <Er$cfg@cs.psu.edu> <12099@goofy.megatest.UUCP> <98399@linus.UUCP> <E5$4$m@cs.psu.edu> <98717@linus.UUCP> <E*er-q@cs.psu.edu>
Reply-To: karl@haddock.ima.isc.com (Karl Heuer)
Organization: Interactive Systems, Cambridge, MA 02138-5302
Lines: 15

In article <E*er-q@cs.psu.edu> callahan@mordor.endor.cs.psu.edu (Paul B. Callahan) writes:
>After seeing enough mathematics, I was ultimately convinced that my intuition
>was at fault.

A similarly confusing point is that the negative of a negative number is
positive.  Ah, the memories of being a TA...

>If we assume that floating point arithmetic is done using a sign-magnitude
>representation [then truncate is probably easier than floor to implement].

But, given that most implementations use two's complement for integers, and
even for floating-point exponents, why *is* sign-magnitude the standard for
floating point significands?

Karl W. Z. Heuer (karl@ima.ima.isc.com or harvard!ima!karl), The Walking Lint