NAME

       cosh, coshf, coshl - hyperbolic cosine function

LIBRARY

       Math library (libm, -lm)

SYNOPSIS

       #include <math.h>

       double cosh(double x);
       float coshf(float x);
       long double coshl(long double x);

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

       coshf(), coshl():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

       These functions return the hyperbolic cosine of x, which is defined mathematically as:

           cosh(x) = (exp(x) + exp(-x)) / 2

RETURN VALUE

       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.

ERRORS

       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.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌───────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │Interface                                                      │ Attribute     │ Value   │
       ├───────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │cosh(), coshf(), coshl()                                       │ Thread safety │ MT-Safe │
       └───────────────────────────────────────────────────────────────┴───────────────┴─────────┘

STANDARDS

       C11, POSIX.1-2008.

HISTORY

       C99, POSIX.1-2001.

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

BUGS

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

SEE ALSO

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