vec_rsqrte

Purpose

Returns a vector containing estimates of the reciprocal square roots of the corresponding elements of the given vector.

Syntax

d=vec_rsqrte(a)

Result and argument types

The following table describes the types of the returned value and the function arguments.

d	a
`vector4double`	`vector4double`

Result value

Each element of the result contains the estimated value of the reciprocal square root of the corresponding element of a.

Note:

The precision guarantee is specified by the following expression, where x is the value of each element of a and r is the value of the corresponding element of the result value:

| (r-1/√x) / 1/√x | ≤ 1/32

Special operands

Special operands are handled as follows:

Operand	Estimate	Exception
-Infinity	QNaN²	VXSQRT
<0	QNaN²	VXSQRT
-0	-Infinity¹	ZX
+0	+Infinity¹	ZX
+Infinity	+0	None
SNaN	QNaN²	VXSNAN
QNaN	QNaN	None
No result if FPSCR_ZE = 1. No result if FPSCR_VE = 1.

Formula

d[0] = 1 / √a[0]
d[1] = 1 / √a[1]
d[2] = 1 / √a[2]
d[3] = 1 / √a[3]

Example

a =  (4.0, 16.0, 25.0,  64.0)
d: (0.5, 0.25,  0.2, 0.125)