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### 1.40 `tanh`, `tanhf`—hyperbolic tangent

Synopsis

         #include <math.h>
         double tanh(double x);
         float tanhf(float x);

Description

`tanh` computes the hyperbolic tangent of the argument x. Angles are specified in radians.

`tanh(`x`)` is defined as

          sinh(x)/cosh(x)

`tanhf` is identical, save that it takes and returns `float` values.

Returns
The hyperbolic tangent of x is returned.

Portability
`tanh` is ANSI C. `tanhf` is an extension.