﻿ f06ej Method
f06ej returns the Euclidean norm of the $n$-element real vector $x$.

# Syntax

C#
```public static double f06ej(
int n,
double[] x,
int incx,
out int ifail
)```
Visual Basic
```Public Shared Function f06ej ( _
n As Integer, _
x As Double(), _
incx As Integer, _
<OutAttribute> ByRef ifail As Integer _
) As Double```
Visual C++
```public:
static double f06ej(
int n,
array<double>^ x,
int incx,
[OutAttribute] int% ifail
)```
F#
```static member f06ej :
n : int *
x : float[] *
incx : int *
ifail : int byref -> float
```

#### Parameters

n
Type: System..::..Int32
On entry: $n$, the number of elements in $x$.
x
Type: array<System..::..Double>[]()[][]
An array of size [dim1]
Note: the dimension of the array x must be at least $\mathrm{max}\phantom{\rule{0.125em}{0ex}}\left(1,1+\left({\mathbf{n}}-1\right)×{\mathbf{incx}}\right)$.
On entry: the $n$-element vector $x$. ${x}_{\mathit{i}}$ must be stored in ${\mathbf{x}}\left[1+\left(\mathit{i}-1\right)×{\mathbf{incx}}\right]$, for $\mathit{i}=1,2,\dots ,{\mathbf{n}}$.
Intermediate elements of x are not referenced.
incx
Type: System..::..Int32
On entry: the increment in the subscripts of x between successive elements of $x$.
Constraint: ${\mathbf{incx}}>0$.
ifail
Type: System..::..Int32%
On exit: $\mathbf{ifail}=0$ unless the method detects an error (see [Error Indicators and Warnings]).

#### Return Value

f06ej returns the Euclidean norm of the $n$-element real vector $x$.

# Description

f06ej returns the Euclidean norm
 $x2=xTx$
of the $n$-element real vector $x$ scattered with stride incx.

# 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

# Error Indicators and Warnings

${\mathbf{ifail}}=-9000$
An error occured, see message report.
${\mathbf{ifail}}=-8000$
Negative dimension for array $〈\mathit{\text{value}}〉$
${\mathbf{ifail}}=-6000$
Invalid Parameters $〈\mathit{\text{value}}〉$
${\mathbf{ifail}}=-6000$
Invalid Parameters $〈\mathit{\text{value}}〉$

Not applicable.

None.