F06FEF (PDF version)
F06 Chapter Contents
F06 Chapter Introduction
NAG Library Manual
NAG Library Routine Document
F06FEF
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
Further Comments
9
Example
1 Purpose
F06FEF multiplies a real vector by the reciprocal of a scalar.
2 Specification
SUBROUTINE F06FEF (
N
,
ALPHA
,
X
,
INCX
)
INTEGER
N, INCX
REAL (KIND=nag_wp)
ALPHA, X(*)
3 Description
F06FEF performs the operation
x
←
1
α
x
where
x
is an
n
-element real vector scattered with stride
INCX
and
α
is a real nonzero scalar.
4 References
None.
5 Parameters
1: N – INTEGER
Input
On entry
:
n
, the number of elements in
x
.
2: ALPHA – REAL (KIND=nag_wp)
Input
On entry
: the scalar
α
.
Constraint
:
ALPHA
≠
0.0
.
3: X(
*
) – REAL (KIND=nag_wp) array
Input/Output
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.
On exit
: the updated vector
x
, stored in the same array elements used to supply the original vector.
4: 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 Further Comments
None.
9 Example
None.
F06FEF (PDF version)
F06 Chapter Contents
F06 Chapter Introduction
NAG Library Manual
© The Numerical Algorithms Group Ltd, Oxford, UK. 2012