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Re: Negative zeros?
From: |
Przemek Klosowski |
Subject: |
Re: Negative zeros? |
Date: |
Wed, 14 Sep 2005 15:59:51 -0400 (EDT) |
I am sorry, John, David, and Stephan. I am a mathematician. I don't
choose to read nonsense. Zero is zero is zero.
I realize that e-1000000 is positive and -e-1000000 is negative and
that these might be represented by 0 and -0 respectively on a
machine. But I will never accept that
0 * (-1) = -0.
OK, so as a mathematician you should be well receptive to Kahan's
arguments, stemming from the complex analysis where there is a
definite need to distinguish lim(x>0, x->0) from lim(x<0, x->0)
because of branch cuts---otherwise, what would be the value of
sqrt(i*x-1) in each case?
Actually, Octave doesn't do it this way; sqrt(-1-0i)=sqrt(-1+0i)
but the concept of signed zeros does make sense if you understand
when it's appropriate.
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Re: Negative zeros?, Tom Holroyd, 2005/09/13
Re: Negative zeros?, Tom Holroyd, 2005/09/14