Available in all subroutines.

Computes the inverse hyperbolic sine of its argument x.


x - Floating point value representing the area of a hyperbolic sector.

Return Value

Upon successful completion, this function returns the inverse hyperbolic sine of x.

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

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

If x is subnormal, a range error occurs and x will be returned.


If the x argument is subnormal, then fastly.error will be set to ERANGE.


declare local FLOAT;
set = math.asinh(1);

User contributed notes

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