double acosh (double x); float acoshf (float x); long double acoshl (long double x);
Returns the nonnegative arc hyperbolic cosine of x, expressed in radians.
The arc hyperbolic cosine is the inverse operation of the hyperbolic cosine.
- Value whose arc hyperbolic cosine is computed.
- If the argument is less than 1, a domain error occurs.
Nonnegative arc hyperbolic cosine of x, in the interval [0,+INFINITY] radians.
Note that the negative of this value is also a valid arc hyperbolic cosine of x One radian is equivalent to 180/PI degrees.
If a domain error occurs:
- And math_errhandling has MATH_ERRNO set: the global variable errno is set to EDOM.
- And math_errhandling has MATH_ERREXCEPT set: FE_INVALID is raised.