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99 lines
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99 lines
3.8 KiB
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<a name="frexp"></a>
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<p>
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Next: <a href="gamma.html#gamma" accesskey="n" rel="next">gamma</a>, Previous: <a href="fmod.html#fmod" accesskey="p" rel="prev">fmod</a>, Up: <a href="Math.html#Math" accesskey="u" rel="up">Math</a> [<a href="Document-Index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Document-Index.html#Document-Index" title="Index" rel="index">Index</a>]</p>
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<a name="frexp_002c-frexpf_002d_002d_002dsplit-floating_002dpoint-number"></a>
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<h3 class="section">1.26 <code>frexp</code>, <code>frexpf</code>—split floating-point number</h3>
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<a name="index-frexp"></a>
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<a name="index-frexpf"></a>
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<p><strong>Synopsis</strong>
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</p><div class="example">
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<pre class="example">#include <math.h>
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double frexp(double <var>val</var>, int *<var>exp</var>);
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float frexpf(float <var>val</var>, int *<var>exp</var>);
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</pre></div>
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<p><strong>Description</strong><br>
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All nonzero, normal numbers can be described as <var>m</var> * 2**<var>p</var>.
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<code>frexp</code> represents the double <var>val</var> as a mantissa <var>m</var>
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and a power of two <var>p</var>. The resulting mantissa will always
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be greater than or equal to <code>0.5</code>, and less than <code>1.0</code> (as
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long as <var>val</var> is nonzero). The power of two will be stored
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in <code>*</code><var>exp</var>.
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</p>
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<p><var>m</var> and <var>p</var> are calculated so that
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<var>val</var> is <var>m</var> times <code>2</code> to the power <var>p</var>.
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</p>
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<p><code>frexpf</code> is identical, other than taking and returning
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floats rather than doubles.
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</p>
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<br>
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<p><strong>Returns</strong><br>
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<code>frexp</code> returns the mantissa <var>m</var>. If <var>val</var> is <code>0</code>, infinity,
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or Nan, <code>frexp</code> will set <code>*</code><var>exp</var> to <code>0</code> and return <var>val</var>.
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</p>
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<br>
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<p><strong>Portability</strong><br>
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<code>frexp</code> is ANSI.
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<code>frexpf</code> is an extension.
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</p>
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