Contents

# p?symm

Performs a scalar-matrix-matrix product (one matrix operand is symmetric) and adds the result to a scalar-matrix product for distribute matrices.

## Syntax

Include Files
• mkl_pblas.h
Description
The
p?symm
routines perform a matrix-matrix operation with distributed matrices. The operation is defined as
`sub(C):=alpha*sub(A)*sub(B)+ beta*sub(C),`
or
`sub(C):=alpha*sub(B)*sub(A)+ beta*sub(C),`
where:
alpha
and
beta
are scalars,
sub(
A
)
is a symmetric distributed matrix,
sub(
A
)=
A
(
ia
:
ia
+
m
-1,
ja
:
ja
+
m
-1)
, if
side
=
'L'
, and
sub(
A
)=
A
(
ia
:
ia
+
n
-1,
ja
:
ja
+
n
-1)
, if
side
=
'R'
.
sub(
B
)
and
sub(
C
)
are
m
-by-
n
distributed matrices.
sub(
B
)=
B
(
ib
:
ib
+
m
-1,
jb
:
jb
+
n
-1)
,
sub(
C
)=
C
(
ic
:
ic
+
m
-1,
jc
:
jc
+
n
-1)
.
Input Parameters
side
(global) Specifies whether the symmetric distributed matrix
sub(
A
)
appears on the left or right in the operation:
if
side
=
'L'
or
'l'
, then
sub(
C
) :=
alpha
*sub(
A
) *sub(
B
) +
beta
*sub(
C
)
;
if
side
=
'R'
or
'r'
, then
sub(
C
) :=
alpha
*sub(
B
) *sub(
A
) +
beta
*sub(
C
)
.
uplo
(global) 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 is used;
if
uplo
=
'L'
or
'l'
, then the lower triangular part is used.
m
(global) Specifies the number of rows of the distribute submatrix
sub(
C
)
,
m
0.
n
(global) Specifies the number of columns of the distribute submatrix
sub(
C
)
,
m
0.
alpha
(global)
Specifies the scalar
alpha
.
a
(local)
Array, size
(
lld_a
, LOCq(
ja
+
na
-1))
.
Before entry this array must contain the local pieces of the symmetric distributed matrix
sub(
A
)
, such that when
uplo
=
'U'
or
'u'
, the
na
-by-
na
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
na
-by-
na
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) 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
.
b
(local)
Array, size
(
lld_b
, LOCq(
jb
+
n
-1) )
. Before entry this array must contain the local pieces of the distributed matrix
sub(
B
)
.
ib
,
jb
(global) The row and column indices in the distributed matrix
B
indicating the first row and the first column of the submatrix
sub(
B
)
, respectively.
descb
(global and local) array of dimension 9. The array descriptor of the distributed matrix
B
.
beta
(global)
Specifies the scalar
beta
.
When
beta
is set to zero, then
sub(
C
)
need not be set on input.
c
(local)
Array, size
(
lld_c
, LOCq(
jc
+
n
-1) )
. Before entry this array must contain the local pieces of the distributed matrix
sub(
C
)
.
ic
,
jc
(global) The row and column indices in the distributed matrix
C
indicating the first row and the first column of the submatrix
sub(
C
)
, respectively.
descc
(global and local) array of dimension 9. The array descriptor of the distributed matrix
C
.
Output Parameters
c
Overwritten by the
m
-by-
n
updated matrix.

#### 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