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| <h3 class="section">1.25 <code>frexp</code>, <code>frexpf</code>—split floating-point number</h3> |
| |
| <p><a name="index-frexp-61"></a><a name="index-frexpf-62"></a><strong>Synopsis</strong> |
| <pre class="example"> #include <math.h> |
| double frexp(double <var>val</var>, int *<var>exp</var>); |
| float frexpf(float <var>val</var>, int *<var>exp</var>); |
| |
| </pre> |
| <p><strong>Description</strong><br> |
| All nonzero, normal numbers can be described as <var>m</var> * 2**<var>p</var>. |
| <code>frexp</code> represents the double <var>val</var> as a mantissa <var>m</var> |
| and a power of two <var>p</var>. The resulting mantissa will always |
| be greater than or equal to <code>0.5</code>, and less than <code>1.0</code> (as |
| long as <var>val</var> is nonzero). The power of two will be stored |
| in <code>*</code><var>exp</var>. |
| |
| <p><var>m</var> and <var>p</var> are calculated so that |
| <var>val</var> is <var>m</var> times <code>2</code> to the power <var>p</var>. |
| |
| <p><code>frexpf</code> is identical, other than taking and returning |
| floats rather than doubles. |
| |
| <p><br> |
| <strong>Returns</strong><br> |
| <code>frexp</code> returns the mantissa <var>m</var>. If <var>val</var> is <code>0</code>, infinity, |
| or Nan, <code>frexp</code> will set <code>*</code><var>exp</var> to <code>0</code> and return <var>val</var>. |
| |
| <p><br> |
| <strong>Portability</strong><br> |
| <code>frexp</code> is ANSI. |
| <code>frexpf</code> is an extension. |
| |
| <p><br> |
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