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Name

cosh, coshf, coshl - hyperbolic cosine function

Synopsis


#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():

_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or cc -std=c99

Description

The cosh() function returns 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.

Conforming to

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

Bugs

In glibc version 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)

Colophon

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