Contents

# p?hemm

Performs a scalar-matrix-matrix product (one matrix operand is Hermitian) and adds the result to a scalar-matrix product.

## Syntax

Include Files
• mkl_pblas.h
Description
The
p?hemm
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 Hermitian 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 Hermitian 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 Hermitian 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
)
,
n
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 Hermitian 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 Hermitian 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 distributed matrix.

#### Product and Performance Information

1

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Notice revision #20110804