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NNTP-Posting-Date: Sat, 21 May 2011 21:00:42 -0500
Date: Sat, 21 May 2011 19:00:39 -0700
From: Patricia Shanahan <pats@acm.org>
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Subject: Re: About using assertion
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On 5/21/2011 4:37 PM, Tim McDaniel wrote:
> In article<se-dnUMuGp0Fj0jQnZ2dnUVZ_o-dnZ2d@earthlink.com>,
> Patricia Shanahan<pats@acm.org>  wrote:
>> Negative zero is a strange beast. As far as I can tell, it exists
>> mainly to produce negative infinity when it is used as a divisor. For
>> example, it is equal to zero for comparison purposes.
>
> Hm, I thought it didn't, but the authoritative-looking but old
> <http://www.concentric.net/~ttwang/tech/javafloat.htm>  says otherwise.

The ultimate authority on comparison in Java is, of course, the JLS.
Section "15.20.1 Numerical Comparison Operators <, <=, >, and >=" says
in the paragraph about floating-point comparisons "Positive zero and
negative zero are considered equal."

[http://java.sun.com/docs/books/jls/third_edition/html/expressions.html#15.20.1]

> However, Float/Double apparently acts differently from float/double:

The Java Comparable interface takes a rather different view of ordering
from IEEE 754, requiring some adjustments.

Patricia