Contents

p?atrmv

Computes a distributed matrix-vector product using absolute values for a triangular matrix.

Syntax

Include Files
• mkl_pblas.h
Description
The
p?atrmv
routines perform one of the following distributed matrix-vector operations defined as
sub(
y
) := abs(
alpha
)*abs(sub(
A
))*abs(sub(
x
))+ abs(
beta
*sub(
y
))
, or
sub(
y
) := abs(
alpha
)*abs(sub(
A
)')*abs(sub(
x
))+ abs(
beta
*sub(
y
))
, or
sub(
y
) := abs(
alpha
)*abs(conjg(sub(
A
)'))*abs(sub(
x
))+ abs(
beta
*sub(
y
))
,
where:
alpha
and
beta
are scalars,
sub(
A
)
is a
n
-by-
n
unit, or non-unit, upper or lower triangular distributed matrix,
sub(
A
) =
A
(
ia
:
ia
+
n
-1,
ja
:
ja
+
n
-1)
,
sub(
x
)
is an
n
-element distributed vector.
sub(
x
)
denotes
X
(
ix
,
jx
:
jx
+
n
-1)
if
incx
=
m_x
, and
X
(
ix
:
ix
+
n
-1,
jx
)
if
incx
= 1
.
Input Parameters
uplo
(global) Specifies whether the distributed matrix
sub(
A
)
is upper or lower triangular:
if
uplo
=
'U'
or
'u'
, then the matrix is upper triangular;
if
uplo
=
'L'
or
'l'
, then the matrix is low triangular.
trans
(global) Specifies the form of
op(sub(
A
))
used in the matrix equation:
if
trans
= '
N
'
or
'
n
'
, then
sub(
y
) := |
alpha
|*|sub(
A
)|*|sub(
x
)
|+|
beta
*sub(
y
)|;
if
trans
= '
T
'
or
'
t
'
, then
sub(
y
) := |
alpha
|*|sub(
A
)'|*|sub(
x
)
|+|
beta
*sub(
y
)|;
if
trans
= '
C
'
or
'
c
'
, then
sub(
y
) := |
alpha
|*|conjg(sub(
A
)')|*|sub(
x
)|+|
beta
*sub(
y
)|
.
diag
(global) Specifies whether the matrix
sub(
A
)
is unit triangular:
if
diag
=
'U'
or
'u'
then the matrix is unit triangular;
if
diag
=
'N'
or
'n'
, then the matrix is not unit triangular.
n
(global) Specifies the order of the distributed matrix
sub(
A
)
,
n
0.
alpha
(global)
Specifies the scalar
alpha
.
a
(local)
Array, size at least
(
lld_a
, LOCq(1,
ja
+
n
-1))
.
Before entry with
uplo
=
'U'
or
'u'
, this array contains the local entries corresponding to the entries of the upper triangular distributed matrix
sub(
A
)
, and the local entries corresponding to the entries of the strictly lower triangular part of the distributed matrix
sub(
A
)
is not referenced.
Before entry with
uplo
=
'L'
or
'l'
, this array contains the local entries corresponding to the entries of the lower triangular distributed matrix
sub(
A
)
, and the local entries corresponding to the entries of the strictly upper triangular part of the distributed matrix
sub(
A
)
is not referenced.
When
diag
=
'U'
or
'u'
, the local entries corresponding to the diagonal elements of the submatrix
sub(
A
)
are not referenced either, but are assumed to be unity.
ia
,
ja
(global) The row and column indices in the distributed matrix
A
indicating the first row and the first column of the submatrix
sub(
A
)
, respectively.
desca
(global and local) array of dimension 9. The array descriptor of the distributed matrix
A
.
x
(local)
Array, size at least
(
jx
-1)*
m_x
+
ix
+(
n
-1)*abs(
incx
))
.
This array contains the entries of the distributed vector
sub(
x
)
.
ix
,
jx
(global) The row and column indices in the distributed matrix
X
indicating the first row and the first column of the submatrix
sub(
x
)
, respectively.
descx
(global and local) array of dimension 9. The array descriptor of the distributed matrix
X
.
incx
(global) Specifies the increment for the elements of
sub(
x
)
. Only two values are supported, namely 1 and
m_x
.
incx
must not be zero.
beta
(global)
Specifies the scalar
beta
. When
beta
is set to zero, then
sub(
y
)
need not be set on input.
y
(local)
Array, size
(
jy
-1)*
m_y
+
iy
+(
m
-1)*abs(
incy
))
when
trans
= '
N
'
or
'n'
, and
(
jy
-1)*
m_y
+
iy
+(
n
-1)*abs(
incy
))
otherwise.
This array contains the entries of the distributed vector
sub(
y
)
.
iy
,
jy
(global) The row and column indices in the distributed matrix
Y
indicating the first row and the first column of the submatrix
sub(
y
)
, respectively.
descy
(global and local) array of dimension 9. The array descriptor of the distributed matrix
Y
.
incy
(global) Specifies the increment for the elements of
sub(
y
)
. Only two values are supported, namely 1 and
m_y
.
incy
must not be zero.
Output Parameters
y
Overwritten by the transformed distributed vector
sub(
y
)
.

Product and Performance Information

1

Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804