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| <h3 class="section">1.13 <code>cosh</code>, <code>coshf</code>—hyperbolic cosine</h3> |
| |
| <p><strong>Synopsis</strong> |
| <pre class="example"> #include <math.h> |
| double cosh(double <var>x</var>); |
| float coshf(float <var>x</var>) |
| |
| </pre> |
| <p><strong>Description</strong><br> |
| |
| <p><code>cosh</code> computes the hyperbolic cosine of the argument <var>x</var>. |
| <code>cosh(</code><var>x</var><code>)</code> is defined as |
| <pre class="smallexample"> (exp(x) + exp(-x))/2 |
| </pre> |
| <p>Angles are specified in radians. |
| <code>coshf</code> is identical, save that it takes and returns <code>float</code>. |
| |
| <p><br> |
| <strong>Returns</strong><br> |
| The computed value is returned. When the correct value would create |
| an overflow, <code>cosh</code> returns the value <code>HUGE_VAL</code> with the |
| appropriate sign, and the global value <code>errno</code> is set to <code>ERANGE</code>. |
| |
| <p>You can modify error handling for these functions using the |
| function <code>matherr</code>. |
| |
| <p><br> |
| <strong>Portability</strong><br> |
| <code>cosh</code> is ANSI. |
| <code>coshf</code> is an extension. |
| |
| <p><br> |
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