tanh - Man Page

hyperbolic tangent function


Math library (libm, -lm)


#include <math.h>

double tanh(double x);
float tanhf(float x);
long double tanhl(long double x);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

tanhf(), tanhl():

    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
        || /* glibc <= 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)

Return Value

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).

tanh(), tanhf(), tanhl()Thread safetyMT-Safe


C99, POSIX.1-2001, POSIX.1-2008.

The variant returning double also conforms to SVr4, 4.3BSD.

See Also

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

Referenced By

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

The man pages tanhf(3) and tanhl(3) are aliases of tanh(3).

2023-02-05 Linux man-pages 6.03