NAG Library Routine Document

F06BMF

+− Contents

1 Purpose

9 Example

F06BMF completes the safe computation of the Euclidean length of a vector, following a call to F06FJF or F06KJF.

FUNCTION F06BMF (

REAL (KIND=nag_wp) F06BMF

REAL (KIND=nag_wp)

SCAL, SSQ

F06BMF completes the safe computation of the Euclidean length of a vector, following a call to F06FJF or F06KJF which return values

α

and

ξ

such that

{‖x‖}_{2}^{2} = α^{2} ξ .

F06BMF returns, via the function name, the value

\min (α \sqrt{ξ}, flmax),

where

flmax

is the value given by

1 / (X02AMF)

None.

1: SCAL – REAL (KIND=nag_wp)Input: On entry: the scaling factor $α$ , returned by F06FJF or F06KJF.
Constraint: $SCAL \geq 0.0$ .
2: SSQ – REAL (KIND=nag_wp)Input: On entry: the scaled sum of squares $ξ$ , returned by F06FJF or F06KJF.
Constraint: $SSQ \geq 1.0$ .