NAG FL Interface
f06ejf (dnrm2)

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1 Purpose

f06ejf returns the Euclidean norm of the n-element real vector x.

2 Specification

Fortran Interface
Function f06ejf ( n, x, incx)
Real (Kind=nag_wp) :: f06ejf
Integer, Intent (In) :: n, incx
Real (Kind=nag_wp), Intent (In) :: x(*)
C Header Interface
#include <nag.h>
double  f06ejf_ (const Integer *n, const double x[], const Integer *incx)
The routine may be called by the names f06ejf, nagf_blas_dnrm2 or its BLAS name dnrm2.

3 Description

f06ejf returns, via the function name, the Euclidean norm
of the n-element real vector x scattered with stride incx.

4 References

Lawson C L, Hanson R J, Kincaid D R and Krogh F T (1979) Basic linear algebra supbrograms for Fortran usage ACM Trans. Math. Software 5 308–325

5 Arguments

1: n Integer Input
On entry: n, the number of elements in x.
2: x(*) Real (Kind=nag_wp) array Input
Note: the dimension of the array x must be at least max(1, 1+(n-1) ×incx ) .
On entry: the n-element vector x. xi must be stored in x(1+(i-1)×incx), for i=1,2,,n.
Intermediate elements of x are not referenced.
3: incx Integer Input
On entry: the increment in the subscripts of x between successive elements of x.
Constraint: incx>0.

6 Error Indicators and Warnings


7 Accuracy

Not applicable.

8 Parallelism and Performance

Background information to multithreading can be found in the Multithreading documentation.
f06ejf is not threaded in any implementation.

9 Further Comments


10 Example