NAG Library Routine Document

f06bmf (dnorm)

1
Purpose

f06bmf completes the safe computation of the Euclidean length of a vector, following a call to f06fjf or f06kjf.

2
Specification

Fortran Interface
Function f06bmf ( scal, ssq)
Real (Kind=nag_wp):: f06bmf
Real (Kind=nag_wp), Intent (In):: scal, ssq
C Header Interface
#include <nagmk26.h>
double  f06bmf_ (const double *scal, const double *ssq)

3
Description

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
x22=α2ξ.  
f06bmf returns, via the function name, the value
minαξ,flmax,  
where flmax is the value given by 1/x02amf.

4
References

None.

5
Arguments

1:     scal – Real (Kind=nag_wp)Input
On entry: the scaling factor α, returned by f06fjf or f06kjf.
Constraint: scal0.0.
2:     ssq – Real (Kind=nag_wp)Input
On entry: the scaled sum of squares ξ, returned by f06fjf or f06kjf.
Constraint: ssq1.0.

6
Error Indicators and Warnings

None.

7
Accuracy

Not applicable.

8
Parallelism and Performance

f06bmf is not threaded in any implementation.

9
Further Comments

None.

10
Example

None.