F06HCF (PDF version)
F06 Chapter Contents
F06 Chapter Introduction
NAG Library Manual
NAG Library Routine Document
F06HCF
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
F06HCF multiplies a complex vector by a complex diagonal matrix.
2 Specification
SUBROUTINE F06HCF (
N
,
D
,
INCD
,
X
,
INCX
)
INTEGER
N, INCD, INCX
COMPLEX (KIND=nag_wp)
D(*), X(*)
3 Description
F06HCF performs the operation
x
←
D
x
where
x
is an
n
-element complex vector and
D
=
diag
d
is a complex diagonal matrix.
Equivalently, the routine performs the element-by-element product of the vectors
x
and
d
x
i
=
d
i
x
i
,
i
=
1
,
2
,
…
,
n
.
4 References
None.
5 Parameters
1: N – INTEGER
Input
On entry
:
n
, the number of elements in
d
and
x
.
2: D(
*
) – COMPLEX (KIND=nag_wp) array
Input
Note:
the dimension of the array
D
must be at least
max
1
,
1
+
N
-
1
×
INCD
.
On entry
: the vector
d
.
If
INCD
>
0
,
d
i
must be stored in
D
1
+
i
-
1
×
INCD
, for
i
=
1
,
2
,
…
,
N
.
If
INCD
<
0
,
d
i
must be stored in
D
1
-
N
-
i
×
INCD
, for
i
=
1
,
2
,
…
,
N
.
3: INCD – INTEGER
Input
On entry
: the increment in the subscripts of
D
between successive elements of
d
.
4: X(
*
) – COMPLEX (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 array
X
must contain the
n
-element vector
x
.
If
INCX
>
0
,
x
i
must be stored in
X
1
+
i
-
1
×
INCX
, for
i
=
1
,
2
,
…
,
N
.
If
INCX
<
0
,
x
i
must be stored in
X
1
-
N
-
i
×
INCX
, for
i
=
1
,
2
,
…
,
N
.
On exit
: the updated vector
x
stored in the array elements used to supply the original vector
x
.
Intermediate elements of
X
are unchanged.
5: INCX – INTEGER
Input
On entry
: the increment in the subscripts of
X
between successive elements of
x
.
6 Error Indicators and Warnings
None.
7 Accuracy
Not applicable.
8 Further Comments
None.
9 Example
None.
F06HCF (PDF version)
F06 Chapter Contents
F06 Chapter Introduction
NAG Library Manual
© The Numerical Algorithms Group Ltd, Oxford, UK. 2012