## Developer Reference

• 2020.2
• 07/15/2020
• Public Content
Contents

# p?symv

Computes a distributed matrix-vector product using a symmetric matrix.

## Syntax

Include Files
• mkl_pblas.h
Description
The
p?symv
routines perform a distributed matrix-vector operation defined as
`sub(y)  := alpha*sub(A)*sub(x) + beta*sub(y),`
where:
alpha
and
beta
are scalars,
sub(
A
)
is a
n
-by-
n
symmetric distributed matrix,
sub(
A
)=
A
(
ia
:
ia
+
n
-1,
ja
:
ja
+
n
-1)
,
sub(
x
)
and
sub(
y
)
are distributed vectors.
sub(
x
)
denotes
X
(
ix
,
jx
:
jx
+
n
-1)
if
incx
=
m_x
, and
X
(
ix
:
ix
+
n
-1,
jx
)
if
incx
= 1,
sub(
y
)
denotes
Y
(
iy
,
jy
:
jy
+
n
-1)
if
incy
=
m_y
, and
Y
(
iy
:
iy
+
n
-1,
jy
)
if
incy
= 1
.
Input Parameters
uplo
(global)
CHARACTER*1
.
Specifies whether the upper or lower triangular part of the symmetric distributed matrix
sub(
A
)
is used:
If
uplo
=
'U'
or
'u'
, then the upper triangular part of the
sub(
A
)
is used.
If
uplo
=
'L'
or
'l'
, then the low triangular part of the
sub(
A
)
is used.
n
(global)
INTEGER
.
Specifies the order of the distributed matrix
sub(
A
)
,
n
0.
alpha
(global)
REAL
for
pssymv
DOUBLE REAL
for
pdsymv
Specifies the scalar
alpha
.
a
(local)
REAL
for
pssymv
DOUBLE REAL
for
pdsymv
Array, size
(
lld_a
, LOCq(
ja
+
n
-1))
. This array contains the local pieces of the distributed matrix
sub(
A
)
.
Before entry when
uplo
=
'U'
or
'u'
, the
n
-by-
n
upper triangular part of the distributed matrix
sub(
A
)
must contain the upper triangular part of the symmetric distributed matrix and the strictly lower triangular part of
sub(
A
)
is not referenced, and when
uplo
=
'L'
or
'l'
, the
n
-by-
n
lower triangular part of the distributed matrix
sub(
A
)
must contain the lower triangular part of the symmetric distributed matrix and the strictly upper triangular part of
sub(
A
)
is not referenced.
ia
,
ja
(global)
INTEGER
.