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

cosh, coshf, coshl - hyperbolic cosine function

#include <math.h>
double cosh(double x);
float coshf(float x);
long double coshl(long double x);
Link with -lm.

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

These functions return the hyperbolic cosine of x, which is defined mathematically as:
    cosh(x) = (exp(x) + exp(-x)) / 2

On success, these functions return the hyperbolic cosine of x.
If x is a NaN, a NaN is returned.
If x is +0 or -0, 1 is returned.
If x is positive infinity or negative infinity, positive infinity is returned.
If the result overflows, a range error occurs, and the functions return +HUGE_VAL, +HUGE_VALF, or +HUGE_VALL, respectively.

See math_error(7) for information on how to determine whether an error has occurred when calling these functions.
The following errors can occur:
Range error: result overflow
errno is set to ERANGE. An overflow floating-point exception (FE_OVERFLOW) is raised.

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

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

In glibc version 2.3.4 and earlier, an overflow floating-point (FE_OVERFLOW) exception is not raised when an overflow occurs.

acosh(3), asinh(3), atanh(3), ccos(3), sinh(3), tanh(3)