Developer Reference

  • 2021.1
  • 12/04/2020
  • Public Content
Contents

p?herk

Performs a rank-k update of a distributed Hermitian matrix.

Syntax

void pcherk
(
const char
*uplo
,
const char
*trans
,
const MKL_INT
*n
,
const MKL_INT
*k
,
const float
*alpha
,
const MKL_Complex8
*a
,
const MKL_INT
*ia
,
const MKL_INT
*ja
,
const MKL_INT
*desca
,
const float
*beta
,
MKL_Complex8
*c
,
const MKL_INT
*ic
,
const MKL_INT
*jc
,
const MKL_INT
*descc
);
void pzherk
(
const char
*uplo
,
const char
*trans
,
const MKL_INT
*n
,
const MKL_INT
*k
,
const double
*alpha
,
const MKL_Complex16
*a
,
const MKL_INT
*ia
,
const MKL_INT
*ja
,
const MKL_INT
*desca
,
const double
*beta
,
MKL_Complex16
*c
,
const MKL_INT
*ic
,
const MKL_INT
*jc
,
const MKL_INT
*descc
);
Include Files
  • mkl_pblas.h
Description
The
p?herk
routines perform a distributed matrix-matrix operation defined as
sub(C):=alpha*sub(A)*conjg(sub(A)')+ beta*sub(C),
or
sub(C):=alpha*conjg(sub(A)')*sub(A)+ beta*sub(C),
where:
alpha
and
beta
are scalars,
sub(
C
)
is an
n
-by-
n
Hermitian distributed matrix,
sub(
C
)=C(
ic
:
ic
+
n
-1,
jc
:
jc
+
n
-1)
.
sub(
A
)
is a distributed matrix,
sub(
A
)=
A
(
ia
:
ia
+
n
-1,
ja
:
ja
+
k
-1)
, if
trans
= '
N
'
or
'
n
'
, and
sub(
A
)=
A
(
ia
:
ia
+
k
-1,
ja
:
ja
+
n
-1)
otherwise.
Input Parameters
uplo
(global) Specifies whether the upper or lower triangular part of the Hermitian distributed matrix
sub(
C
)
is used:
If
uplo
=
'U'
or
'u'
, then the upper triangular part of the
sub(
C
)
is used.
If
uplo
=
'L'
or
'l'
, then the low triangular part of the
sub(
C
)
is used.
trans
(global) Specifies the operation:
if
trans
=
'N'
or
'n'
, then
sub(
C
) :=
alpha
*sub(
A
)*conjg(sub(
A
)') +
beta
*sub(
C
)
;
if
trans
=
'C'
or
'c'
, then
sub(
C
) :=
alpha
*conjg(sub(
A
)')*sub(
A
) +
beta
*sub(
C
)
.
n
(global) Specifies the order of the distributed matrix
sub(
C
)
,
n
0.
k
(global) On entry with
trans
=
'N'
or
'n'
,
k
specifies the number of columns of the distributed matrix
sub(
A
)
, and on entry with
trans
=
'T'
or
't'
or
'C'
or
'c'
,
k
specifies the number of rows of the distributed matrix
sub(
A
)
,
k
0.
alpha
(global)
Specifies the scalar
alpha
.
a
(local)
Array, size
(
lld_a
,
kla
)
, where
kla
is
LOCq(
ja
+
k
-1)
when
trans
=
'N'
or
'n'
, and is
LOCq(
ja
+
n
-1)
otherwise. Before entry with
trans
=
'N'
or
'n'
, this array contains the local pieces of the distributed matrix
sub(
A
)
.
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
.
beta
(global)
Specifies the scalar
beta
.
c
(local)
Array, size
(
lld_c
, LOCq(
jc
+
n
-1))
.
Before entry with
uplo
=
'U'
or
'u'
, this array contains
n
-by-
n
upper triangular part of the symmetric distributed matrix
sub(
C
)
and its strictly lower triangular part is not referenced.
Before entry with
uplo
=
'L'
or
'l'
, this array contains
n
-by-
n
lower triangular part of the symmetric distributed matrix
sub(
C
)
and its strictly upper triangular part is not referenced.
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
With
uplo
=
'U'
or
'u'
, the upper triangular part of
sub(
C
)
is overwritten by the upper triangular part of the updated distributed matrix.
With
uplo
=
'L'
or
'l'
, the lower triangular part of
sub(
C
)
is overwritten by the upper triangular part of the updated distributed matrix.

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.