F06JJF (DZNRM2) (PDF version)
F06 Chapter Contents
F06 Chapter Introduction
NAG Library Manual
NAG Library Routine Document
F06JJF (DZNRM2)
Note:
before using this routine, please read the Users' Note for your implementation to check the interpretation of
bold italicised
terms and other implementation-dependent details.
▸
▿
Contents
1
Purpose
2
Specification
3
Description
4
References
5
Parameters
6
Error Indicators and Warnings
7
Accuracy
8
Parallelism and Performance
9
Further Comments
10
Example
1 Purpose
F06JJF (DZNRM2) computes the Euclidean norm of a complex vector.
2 Specification
FUNCTION F06JJF (
N
,
X
,
INCX
)
REAL (KIND=nag_wp) F06JJF
INTEGER
N, INCX
COMPLEX (KIND=nag_wp)
X(*)
The routine may be called by its BLAS name
dznrm2
.
3 Description
F06JJF (DZNRM2) returns the Euclidean norm
x
2
=
x
H
x
of the
n
-element complex vector
x
scattered with stride
INCX
, via the function name.
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 Parameters
1:
N
– INTEGER
Input
On entry
:
n
, the number of elements in
x
.
2:
X
*
– COMPLEX (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
.
x
i
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
None.
7 Accuracy
Not applicable.
8 Parallelism and Performance
Not applicable.
9 Further Comments
None.
10 Example
None.
F06JJF (DZNRM2) (PDF version)
F06 Chapter Contents
F06 Chapter Introduction
NAG Library Manual
© The Numerical Algorithms Group Ltd, Oxford, UK. 2015