Groups > comp.lang.java.programmer > #4399

Re: About using assertion

Date	2011-05-21 19:00 -0700
From	Patricia Shanahan <pats@acm.org>
Newsgroups	comp.lang.java.programmer
Subject	Re: About using assertion
References	<f1e4cc83-8596-4e53-bed7-34a5209fe8c4@k3g2000prl.googlegroups.com> <92r0e9F6lvU1@mid.individual.net> <sjmea8-067.ln1@tmcd-linux-p4.austin.tx.us> <se-dnUMuGp0Fj0jQnZ2dnUVZ_o-dnZ2d@earthlink.com> <juula8-jc3.ln1@tmcd-linux-p4.austin.tx.us>
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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

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Re: About using assertion tmcd@tmcd-p4-linux.austin.tx.us (Tim McDaniel) - 2011-05-19 00:32 -0500
  Re: About using assertion Michal Kleczek <kleku75@gmail.com> - 2011-05-19 08:34 +0200
    Re: About using assertion Lew <noone@lewscanon.com> - 2011-05-19 08:46 -0400
      Re: About using assertion Michal Kleczek <kleku75@gmail.com> - 2011-05-19 15:16 +0200
        Re: About using assertion Lew <noone@lewscanon.com> - 2011-05-19 09:38 -0400
          Re: About using assertion Robert Klemme <shortcutter@googlemail.com> - 2011-05-19 07:41 -0700
            Re: About using assertion Lew <noone@lewscanon.com> - 2011-05-19 11:00 -0400
  Re: About using assertion Patricia Shanahan <pats@acm.org> - 2011-05-19 05:52 -0700
    Re: About using assertion tmcd@tmcd-p4-linux.austin.tx.us (Tim McDaniel) - 2011-05-21 18:37 -0500
      Re: About using assertion Patricia Shanahan <pats@acm.org> - 2011-05-21 19:00 -0700
      Re: About using assertion Lew <noone@lewscanon.com> - 2011-05-22 01:19 -0400

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