## Linux and UNIX Man Pages

Test Your Knowledge in Computers #32
Difficulty: Easy
There are 9 pins in a basic serial port.
True or False?

# tanh(3) [linux man page]

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

NAME
tanh, tanhf, tanhl - hyperbolic tangent function

SYNOPSIS
#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():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or cc -std=c99

DESCRIPTION
The tanh() function returns 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.

ERRORS
No errors occur.

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

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

COLOPHON
This  page is part of release 3.27 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.

2010-09-20								   TANH(3)```

## Check Out this Related Man Page

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

NAME
tanh, tanhf, tanhl - hyperbolic tangent function

SYNOPSIS
#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():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or cc -std=c99

DESCRIPTION
The tanh() function returns 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.

ERRORS
No errors occur.

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