Arm Compiler armasm User Guide : 14.107 VRECPS

14.107 VRECPS

Vector Reciprocal Step.

Syntax

VRECPS{cond}.F32 {Qd}, Qn, Qm

VRECPS{cond}.F32 {Dd}, Dn, Dm

where:

cond: is an optional condition code.
Qd, Qn, Qm: are the destination vector, the first operand vector, and the second operand vector, for a quadword operation.
Dd, Dn, Dm: are the destination vector, the first operand vector, and the second operand vector, for a doubleword operation.

Operation

VRECPS multiplies the elements of one vector by the corresponding elements of another vector, subtracts each of the results from 2, and places the final results into the elements of the destination vector.

The Newton-Raphson iteration:

x_n+1 = x_n (2–dx_n)

converges to (1/d) if x₀ is the result of VRECPE applied to d.

Results for out-of-range inputs

The following table shows the results where input values are out of range:

Table 14-14 Results for out-of-range inputs in VRECPS

1st operand element	2nd operand element	Result element
NaN	-	Default NaN
-	NaN	Default NaN
± 0.0 or denormal	± infinity	2.0
± infinity	± 0.0 or denormal	2.0

Related references

7.11 Condition code suffixes

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