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| 22 | <title>Signed Zeros (GNU C Language Manual)</title>
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| 32 | <link href="Floating-Point-in-Depth.html" rel="up" title="Floating Point in Depth">
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| 58 | <span id="Signed-Zeros"></span><div class="header">
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| 59 | <p>
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| 60 | Next: <a href="Scaling-by-the-Base.html" accesskey="n" rel="next">Scaling by the Base</a>, Previous: <a href="Handling-NaN.html" accesskey="p" rel="prev">Handling NaN</a>, Up: <a href="Floating-Point-in-Depth.html" accesskey="u" rel="up">Floating Point in Depth</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Symbol-Index.html" title="Index" rel="index">Index</a>]</p>
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| 61 | </div>
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| 62 | <hr>
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| 63 | <span id="Signed-Zeros-1"></span><h3 class="section">28.15 Signed Zeros</h3>
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| 64 | <span id="index-signed-zeros-in-floating_002dpoint-arithmetic"></span>
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| 65 | <span id="index-floating_002dpoint-signed-zeros"></span>
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| 66 |
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| 67 | <p>The sign of zero is significant, and important, because it records the
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| 68 | creation of a value that is too small to represent, but came from
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| 69 | either the negative axis, or from the positive axis. Such fine
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| 70 | distinctions are essential for proper handling of <em>branch cuts</em>
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| 71 | in complex arithmetic (see <a href="Complex-Arithmetic.html">Complex Arithmetic</a>).
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| 72 | </p>
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| 73 | <p>The key point about signed zeros is that in comparisons, their sign
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| 74 | does not matter: <code>0.0 == -0.0</code> must <em>always</em> evaluate to
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| 75 | <code>1</code> (true). However, they are not <em>the same number</em>, and
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| 76 | <code>-0.0</code> in C code stands for a negative zero.
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| 77 | </p>
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| 78 |
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