TANH(3) Linux Programmer's Manual TANH(3)

tanh, tanhf, tanhl - hyperbolic tangent function

#include <math.h>
double tanh(double x);
float tanhf(float x);
long double tanhl(long double x);
Link with -lm.

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
tanhf(), tanhl():
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

These functions return the hyperbolic tangent of x, which is defined mathematically as:
    tanh(x) = sinh(x) / cosh(x)

On success, these functions return the hyperbolic tangent of x.
If x is a NaN, a NaN is returned.
If x is +0 (-0), +0 (-0) is returned.
If x is positive infinity (negative infinity), +1 (-1) is returned.

No errors occur.

For an explanation of the terms used in this section, see attributes(7).
Interface Attribute Value
tanh (), tanhf (), tanhl () Thread safety MT-Safe

C99, POSIX.1-2001, POSIX.1-2008.
The variant returning double also conforms to SVr4, 4.3BSD, C89.

acosh(3), asinh(3), atanh(3), cosh(3), ctanh(3), sinh(3)