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| <h3 class="section">1.9 <code>atanh</code>, <code>atanhf</code>—inverse hyperbolic tangent</h3> |
| |
| <p><a name="index-atanh-17"></a><a name="index-atanhf-18"></a><strong>Synopsis</strong> |
| <pre class="example"> #include <math.h> |
| double atanh(double <var>x</var>); |
| float atanhf(float <var>x</var>); |
| |
| </pre> |
| <p><strong>Description</strong><br> |
| <code>atanh</code> calculates the inverse hyperbolic tangent of <var>x</var>. |
| |
| <p><code>atanhf</code> is identical, other than taking and returning |
| <code>float</code> values. |
| |
| <p><br> |
| <strong>Returns</strong><br> |
| <code>atanh</code> and <code>atanhf</code> return the calculated value. |
| |
| <p>If |
| <pre class="smallexample"> <var>x</var>| |
| </pre> |
| <p>is greater than 1, the global <code>errno</code> is set to <code>EDOM</code> and |
| the result is a NaN. A <code>DOMAIN error</code> is reported. |
| |
| <p>If |
| <pre class="smallexample"> <var>x</var>| |
| </pre> |
| <p>is 1, the global <code>errno</code> is set to <code>EDOM</code>; and the result is |
| infinity with the same sign as <code>x</code>. A <code>SING error</code> is reported. |
| |
| <p>You can modify the error handling for these routines using |
| <code>matherr</code>. |
| |
| <p><br> |
| <strong>Portability</strong><br> |
| Neither <code>atanh</code> nor <code>atanhf</code> are ANSI C. |
| |
| <p><br> |
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