Available in all subroutines.

Computes the square root of its argument x.


x - Floating point value.

Return Value

Upon successful completion, this function returns the square root of x.

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

If x is ±0 or math.POS_INFINITY, x will be returned.

If x is a finite value < -0 or math.NEG_INFINITY, a domain error occurs and a NaN will be returned.


If the x argument is < -0 or math.NEG_INFINITY, then fastly.error will be set to EDOM.


declare local FLOAT;
declare local FLOAT;
set = 9.0;
set = math.sqrt(;

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