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math.acos

Available inall subroutines.

Computes the principal value of the arc cosine of its argument x.

Parameters

x - Floating point value. The value of x should be in the range -1 to 1 inclusive.

Return Value

Upon successful completion, this function returns the arc cosine of x in the range 0 to math.PI radians inclusive.

If x is math.NAN, a NaN will be returned.

If x is +1, +0 will be returned.

If x is math.POS_INFINITY or math.NEG_INFINITY, a domain error occurs and a NaN will be returned.

For finite values of x not in the range -1 to 1 inclusive, a domain error occurs and a NaN will be returned.

Errors

If the x argument is finite and is not in the range -1 to 1 inclusive, or is math.POS_INFINITY or math.NEG_INFINITY, then fastly.error will be set to EDOM.

Example

declare local var.fo FLOAT;

set var.fo = math.cos(1.1); // Returns math.NAN

if (fastly.error) {
  set resp.http.acos-error = fastly.error; // Returns "EDOM"
}