## Developer Reference

Contents

Performs sum operation for two distributed triangular matrices.

## Syntax

Include Files
• mkl_pblas.h
Description
The
routines perform sum operation for two distributed triangular matrices. The operation is defined as
`sub(C):=beta*sub(C) + alpha*op(sub(A)),`
where:
op(
x
)
is one of
op(
x
) =
x
, or
op(
x
) =
x
'
, or
op(
x
) = conjg(
x
')
.
alpha
and
beta
are scalars,
sub(
C
)
is an
m
-by-
n
distributed matrix,
sub(
C
)=
C
(
ic
:
ic
+
m
-1,
jc
:
jc
+
n
-1)
.
sub(
A
)
is a distributed matrix,
sub(
A
)=
A
(
ia
:
ia
+
n
-1,
ja
:
ja
+
m
-1)
.
Input Parameters
uplo
(global) Specifies whether the distributed matrix
sub(
C
)
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 operation:
if
trans
=
'N'
or
'n'
, then
op(sub(
A
)) := sub(
A
)
;
if
trans
=
'T'
or
't'
, then
op(sub(
A
)) := sub(
A
)'
;
if
trans
=
'C'
or
'c'
, then
op(sub(
A
)) := conjg(sub(
A
)')
.
m
(global) Specifies the number of rows of the distributed matrix
sub(
C
)
and the number of columns of the submatrix
sub(
A
)
,
m
0.
n
(global) Specifies the number of columns of the distributed matrix
sub(
C
)
and the number of rows of the submatrix
sub(
A
)
,
n
0.
alpha
(global)
Specifies the scalar
alpha
.
a
(local)
Array, size
(
lld_a
, LOCq(
ja
+
m
-1))
. 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
.
When
beta
is equal to zero, then
sub(
C
)
need not be set on input.
c
(local)
Array, size
(
lld_c
, LOCq(
jc
+
n
-1))
.
This array contains 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 updated submatrix.

#### 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