NAG Library Manual, Mark 30
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NAG CL Interface
f16gcc (zaxpby)
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NAG Library Manual, Mark 30
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NAG CL Interface Introduction
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▸
▿
Contents
1
Purpose
2
Specification
3
Description
4
References
5
Arguments
6
Error Indicators and Warnings
7
Accuracy
8
Parallelism and Performance
9
Further Comments
▸
▿
10
Example
10.1
Program Text
10.2
Program Data
10.3
Program Results
© The Numerical Algorithms Group Ltd. 2024
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1
Purpose
f16gcc
computes the sum of two scaled vectors, for complex scalars and vectors.
2
Specification
copy
#include <nag.h>
void
f16gcc
(
Integer
n
,
Complex
alpha
,
const Complex
x
[],
Integer
incx
,
Complex
beta
,
Complex
y
[],
Integer
incy
,
NagError *
fail
)
The function may be called by the names:
f16gcc
,
nag_blast_zaxpby
or
nag_zaxpby
.
3
Description
f16gcc
performs the operation
y
←
α
x
+
β
y
,
where
x
and
y
are
n
-element complex vectors, and
α
and
β
are complex scalars. If
n
is equal to zero, or if
α
is equal to zero and
β
is equal to
1
, this function returns immediately.
4
References
Basic Linear Algebra Subprograms Technical (BLAST) Forum (2001)
Basic Linear Algebra Subprograms Technical (BLAST) Forum Standard
University of Tennessee, Knoxville, Tennessee
https://www.netlib.org/blas/blast-forum/blas-report.pdf
5
Arguments
1:
n
–
Integer
Input
On entry
:
n
, the number of elements in
x
and
y
.
Constraint
:
n
≥
0
.
2:
alpha
–
Complex
Input
On entry
: the scalar
α
.
3:
x
[
dim
]
–
const Complex
Input
Note:
the dimension,
dim
, of the array
x
must be at least
max
(
1
,
1
+
(
n
-
1
)
×
|
incx
|
)
.
On entry
: the
n
-element vector
x
.
If
incx
>
0
,
x
i
must be stored in
x
[
(
i
-
1
)
×
incx
]
, for
i
=
1
,
2
,
…
,
n
.
If
incx
<
0
,
x
i
must be stored in
x
[
(
n
-
i
)
×
|
incx
|
]
, for
i
=
1
,
2
,
…
,
n
.
Intermediate elements of
x
are not referenced. If
n
=
0
,
x
is not referenced and may be
NULL
.
4:
incx
–
Integer
Input
On entry
: the increment in the subscripts of
x
between successive elements of
x
.
Constraint
:
incx
≠
0
.
5:
beta
–
Complex
Input
On entry
: the scalar
β
.
6:
y
[
dim
]
–
Complex
Input/Output
Note:
the dimension,
dim
, of the array
y
must be at least
max
(
1
,
1
+
(
n
-
1
)
×
|
incy
|
)
.
On entry
: the
n
-element vector
y
.
If
incy
>
0
,
y
i
must be stored in
y
[
(
i
-
1
)
×
incy
]
, for
i
=
1
,
2
,
…
,
n
.
If
incy
<
0
,
y
i
must be stored in
y
[
(
n
-
i
)
×
|
incy
|
]
, for
i
=
1
,
2
,
…
,
n
.
Intermediate elements of
y
are not referenced.
On exit
: the updated vector
y
stored in the array elements used to supply the original vector
y
.
Intermediate elements of
y
are unchanged.
7:
incy
–
Integer
Input
On entry
: the increment in the subscripts of
y
between successive elements of
y
.
Constraint
:
incy
≠
0
.
8:
fail
–
NagError *
Input/Output
The NAG error argument (see
Section 7
in the Introduction to the NAG Library CL Interface).
6
Error Indicators and Warnings
NE_ALLOC_FAIL
Dynamic memory allocation failed.
See
Section 3.1.2
in the Introduction to the NAG Library CL Interface for further information.
NE_BAD_PARAM
On entry, argument
⟨
value
⟩
had an illegal value.
NE_INT
On entry,
incx
=
⟨
value
⟩
.
Constraint:
incx
≠
0
.
On entry,
incy
=
⟨
value
⟩
.
Constraint:
incy
≠
0
.
On entry,
n
=
⟨
value
⟩
.
Constraint:
n
≥
0
.
NE_NO_LICENCE
Your licence key may have expired or may not have been installed correctly.
See
Section 8
in the Introduction to the NAG Library CL Interface for further information.
7
Accuracy
The BLAS standard requires accurate implementations which avoid unnecessary over/underflow (see Section 2.7 of
Basic Linear Algebra Subprograms Technical (BLAST) Forum (2001)
).
8
Parallelism and Performance
Background information to multithreading can be found in the
Multithreading
documentation.
f16gcc
makes calls to BLAS and/or LAPACK routines, which may be threaded within the vendor library used by this implementation. Consult the documentation for the vendor library for further information.
Please consult the
X06 Chapter Introduction
for information on how to control and interrogate the OpenMP environment used within this function. Please also consult the
Users' Note
for your implementation for any additional implementation-specific information.
9
Further Comments
None.
10
Example
This example computes the result of a scaled vector accumulation for
α
=
3
+
2
i
,
x
=
(
-
6
+
1.2
i
,
3.7
+
4.5
i
,
-
4
+
2.1
i
)
T
,
β
=
-
i
,
y
=
(
-
5.1
,
6.4
-
5
i
,
-
3
-
2.4
i
)
T
.
x
and
y
are stored in reverse order.
10.1
Program Text
Program Text (f16gcce.c)
10.2
Program Data
Program Data (f16gcce.d)
10.3
Program Results
Program Results (f16gcce.r)
NAG Library Manual, Mark 30
Interfaces:
FL
CL
CPP
AD
PY
MB
NAG CL Interface Introduction
F16 (Blast) Chapter Contents
F16 (Blast) Chapter Introduction
f16gc:
FL
CL
CPP
AD
PY
MB
© The Numerical Algorithms Group Ltd. 2024