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<a name="tanh_002c-tanhf_002d_002d_002dhyperbolic-tangent"></a>
<h3 class="section">1.57 <code>tanh</code>, <code>tanhf</code>—hyperbolic tangent</h3>
<a name="index-tanh"></a>
<a name="index-tanhf"></a>
<p><strong>Synopsis</strong>
</p><div class="example">
<pre class="example">#include <math.h>
double tanh(double <var>x</var>);
float tanhf(float <var>x</var>);
</pre></div>
<p><strong>Description</strong><br>
</p>
<p><code>tanh</code> computes the hyperbolic tangent of
the argument <var>x</var>. Angles are specified in radians.
</p>
<p><code>tanh(<var>x</var>)</code> is defined as
</p><div class="smallexample">
<pre class="smallexample"> sinh(<var>x</var>)/cosh(<var>x</var>)
</pre></div>
<p><code>tanhf</code> is identical, save that it takes and returns <code>float</code> values.
</p>
<br>
<p><strong>Returns</strong><br>
The hyperbolic tangent of <var>x</var> is returned.
</p>
<br>
<p><strong>Portability</strong><br>
<code>tanh</code> is ANSI C. <code>tanhf</code> is an extension.
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