math.atanh
Available inall subroutines.
Computes the inverse hyperbolic tangent of its argument x
.
Parameters
x
- Floating point value representing a hyperbolic angle.
Return Value
Upon successful completion, this function returns the inverse hyperbolic tangent
of x
.
If x
is math.NAN
, a NaN will be returned.
If x
is ±0, x
will be returned.
If x
is math.POS_INFINITY
or
math.NEG_INFINITY
, a domain error occurs
and a NaN will be returned.
If x
is subnormal, a range error occurs and x
will be returned.
For finite |x
|>1, a domain error occurs and a NaN will be returned.
If x
is ±1, a pole error occurs, and math.atanh
will return the value of
the macro math.POS_HUGE_VAL
or
math.NEG_HUGE_VAL
with the same sign as
the result of the function.
Errors
- If the
x
argument is finite and not in the range -1 to 1 inclusive, or if it ismath.POS_INFINITY
ormath.NEG_INFINITY
, thenfastly.error
will be set toEDOM
. - If the
x
argument is subnormal, or ±1, thenfastly.error
will be set toERANGE
.
Example
declare local var.fo FLOAT;
set var.fo = math.atanh(-1); // Returns `math.NEG_INFINITY`
if (fastly.error) { set resp.http.atanh-error = fastly.error; // Returns "ERANGE"}