NAG Library Manual, Mark 27.3
Interfaces:  FL   CL   CPP   AD 
NAG FL Interface Introduction
F06 (Blas) Chapter Contents
F06 (Blas) Chapter Introduction
f06bm:  FL   CL   CPP   AD 

NAG FL Interface
f06bmf (dnorm)

NAG Library Manual, Mark 27.3
Interfaces:  FL   CL   CPP   AD 
NAG FL Interface Introduction
F06 (Blas) Chapter Contents
F06 (Blas) Chapter Introduction
f06bm:  FL   CL   CPP   AD 

▸▿ Contents

© The Numerical Algorithms Group Ltd. 2021
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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 <nag.h>
double  f06bmf_ (const double *scal, const double *ssq)
The routine may be called by the names f06bmf or nagf_blas_dnorm.

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
‖x‖22=α2ξ.  
f06bmf returns, via the function name, the value
min(α⁢ξ,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: scal≥0.0.
2: ssq – Real (Kind=nag_wp) Input
On entry: the scaled sum of squares ξ, returned by f06fjf or f06kjf.
Constraint: ssq≥1.0.

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.
NAG Library Manual, Mark 27.3
Interfaces:  FL   CL   CPP   AD 
NAG FL Interface Introduction
F06 (Blas) Chapter Contents
F06 (Blas) Chapter Introduction
f06bm:  FL   CL   CPP   AD 
© The Numerical Algorithms Group Ltd. 2021