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)):
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or cc -std=c99
The cosh() function returns 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.
C99, POSIX.1-2001. 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.
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