Manpages - acosh.3

acosh, acoshf, acoshl - inverse hyperbolic cosine function

  #include <math.h>

  double acosh(double x);
  float acoshf(float x);
  long double acoshl(long double x);

Link with -lm.

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

*acosh*():

      _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
          || _XOPEN_SOURCE >= 500
          || /* Since glibc 2.19: */ _DEFAULT_SOURCE
          || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

*acoshf*(), *acoshl*():

      _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
          || /* Since glibc 2.19: */ _DEFAULT_SOURCE
          || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

These functions calculate the inverse hyperbolic cosine of x; that is the value whose hyperbolic cosine is x.

On success, these functions return the inverse hyperbolic cosine of x.

If x is a NaN, a NaN is returned.

If x is +1, +0 is returned.

If x is positive infinity, positive infinity is returned.

If x is less than 1, a domain error occurs, and the functions return a NaN.

See *math_error*(7) for information on how to determine whether an error has occurred when calling these functions.

The following errors can occur:

Domain error: x is less than 1

errno is set to EDOM. An invalid floating-point exception (FE_INVALID) is raised.

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

C99, POSIX.1-2001, POSIX.1-2008.

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

*asinh*(3), *atanh*(3), *cacosh*(3), *cosh*(3), *sinh*(3), *tanh*(3)

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