math.acosh
Available inall subroutines.
Computes the inverse hyperbolic cosine of its argument x.
Parameters
x - Floating point value representing the area of a hyperbolic sector.
Return Value
Upon successful completion, this function returns the inverse hyperbolic
cosine of x.
If x is math.NAN, a NaN will be returned.
If x is +1, +0 will be returned.
If x is math.POS_INFINITY,
math.POS_INFINITY will be returned.
If x is math.NEG_INFINITY,
a domain error occurs and a NaN will be returned.
For finite values of x < 1, a domain error occurs and a NaN will be returned.
Errors
If the x argument is finite and less than +1.0, or is
math.NEG_INFINITY,
then fastly.error will be set to EDOM.
Example
declare local var.fo FLOAT;
set var.fo = math.acosh(10);