cosh(3)

cosh3

Hyperbolic cosine function

Usage

#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

Library

Math library (libm, -lm)

Overview

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).

InterfaceAttributeValue
cosh(), coshf(), coshl()Thread safetyMT-Safe

Releases

19 releases since Debian 1.1 (Buzz); the text changed 15 times.

  1. 1.1
  2. 1.2
  3. 1.3–2.2
  4. 3.0
  5. 3.1
  6. 4.0
  7. 5.0
  8. 6.0
  9. 7
  10. 8
  11. 9
  12. 10
  13. 11
  14. 12
  15. 13
  16. Arch

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.

From man-pages 6.19-1 in Arch Linux 2026-11-01. Parsed by carta from the page's man source.