Path: utzoo!utgpu!water!watmath!clyde!rutgers!sri-spam!ames!amdahl!nsc!taux01!amos
From: amos@taux01.UUCP (Amos Shapir)
Newsgroups: comp.lang.c
Subject: Re: Simple question about:  ~
Message-ID: <470@taux01.UUCP>
Date: 29 Jan 88 09:41:52 GMT
References: <1620006@hpcilzb.HP.COM> <2148@chinet.UUCP>
Reply-To: amos%taux01@nsc.com (Amos Shapir)
Organization: National Semiconductor (Israel) Ltd. Home of the 32532
Lines: 20
Hdate: 10 Shvat 5748

Since no one had mentioned this yet, I guess I'll have to:

In article <2148@chinet.UUCP> dag@chinet.UUCP (Daniel A. Glasser) writes:
>in two's complement arithmetic, the additive inverse (negative) of
>a number is computed by taking the 1's complement (all 1's become 0's,
>0's become 1's) of the bit pattern and adding 1.

The definition of 2's complement is actually a little different: the
binary represantation of a negative value is obtained by adding to it
2**n (** means power), where n is the number of bits, and doing a 'pure'
unsigned binary represantation of the result.

E.g. to represent -2 in a 16-bit word:
 -2 + 65536 = 65534 = 0b1111111111111110

-- 
	Amos Shapir			(My other cpu is a NS32532)
National Semiconductor (Israel)
6 Maskit st. P.O.B. 3007, Herzlia 46104, Israel  Tel. +972 52 522261
amos%taux01@nsc.com  34 48 E / 32 10 N