From help-request at octave dot org Wed Sep 14 22:49:41 2005
Subject: Re: Negative zeros?
From: Bill Denney <denney at seas dot upenn dot edu>
To: Vic Norton <vic at norton dot name>
cc: Przemek Klosowski <przemek at jazz dot ncnr dot nist dot gov>, help@octave.org
Date: Wed, 14 Sep 2005 23:45:45 -0400 (EDT)

On Wed, 14 Sep 2005, Vic Norton wrote:

> The 0's I had problems with were never computed. They were assigned. But 
> because of the nature of my routine they were continually being 
> multiplied by -1 (also an integer). If a 0 was multiplied an even number 
> of times it stayed 0, and if a zero was multiplied an odd number of 
> times it became -0. All of this was an artifact of my routine and had no 
> meaning whatsoever. And the 0's and -0's popped up quite randomly in the 
> output.

If you did things normally within octave, then the numbers you were using 
are not integers, they are double precision floating point numbers.  If 
you were actually using ints, then they give the answer you expected:

octave:1> a = 0*-1
a = -0
octave:2> class(a)
ans = double
octave:3> a = int16(0)*int16(-1)
a = 0
octave:4> class(a)
ans = int16

Bill

-- 
"The towels in that hotel were so thick I could hardly close my
suitcase."
   -- Yogi Berra



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