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| <h3 class="section">1.35 <code>log1p</code>, <code>log1pf</code>—log of <code>1 + </code><var>x</var></h3> |
| |
| <p><a name="index-log1p-102"></a><a name="index-log1pf-103"></a><strong>Synopsis</strong> |
| <pre class="example"> #include <math.h> |
| double log1p(double <var>x</var>); |
| float log1pf(float <var>x</var>); |
| |
| </pre> |
| <p><strong>Description</strong><br> |
| <code>log1p</code> calculates |
| the natural logarithm of <code>1+</code><var>x</var>. You can use <code>log1p</code> rather |
| than `<code>log(1+</code><var>x</var><code>)</code>' for greater precision when <var>x</var> is very |
| small. |
| |
| <p><code>log1pf</code> calculates the same thing, but accepts and returns |
| <code>float</code> values rather than <code>double</code>. |
| |
| <p><br> |
| <strong>Returns</strong><br> |
| <code>log1p</code> returns a <code>double</code>, the natural log of <code>1+</code><var>x</var>. |
| <code>log1pf</code> returns a <code>float</code>, the natural log of <code>1+</code><var>x</var>. |
| |
| <p><br> |
| <strong>Portability</strong><br> |
| Neither <code>log1p</code> nor <code>log1pf</code> is required by ANSI C or by the System V |
| Interface Definition (Issue 2). |
| |
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