Contents

# p?trmm

Computes a scalar-matrix-matrix product (one matrix operand is triangular) for distributed matrices.

## Syntax

Include Files
• mkl_pblas.h
Description
The
p?trmm
routines perform a matrix-matrix operation using triangular matrices. The operation is defined as
`sub(B) := alpha*op(sub(A))*sub(B)`
or
`sub(B) := alpha*sub(B)*op(sub(A))`
where:
alpha
is a scalar,
sub(
B
)
is an
m
-by-
n
distributed matrix,
sub(
B
)=
B
(
ib
:
ib
+
m
-1,
jb
:
jb
+
n
-1)
.
A
is a unit, or non-unit, upper or lower triangular distributed matrix,
sub(
A
)=
A
(
ia
:
ia
+
m
-1,
ja
:
ja
+
m
-1)
, if
side
= '
L
'
or
'
l
'
, and
sub(
A
)=
A
(
ia
:
ia
+
n
-1,
ja
:
ja
+
n
-1)
, if
side
= '
R
'
or
'
r
'
.
op(sub(
A
))
is one of
op(sub(
A
)) = sub(
A
)
, or
op(sub(
A
)) = sub(
A
)'
, or
op(sub(
A
)) = conjg(sub(
A
)')
.
Input Parameters
side
(global) Specifies whether
op(sub(
A
))
appears on the left or right of
sub(
B
)
in the operation:
if
side
=
'L'
or
'l'
, then
sub(
B
) :=
alpha
*op(sub(
A
))*sub(
B
)
;
if
side
=
'R'
or
'r'
, then
sub(
B
) :=
alpha
*sub(
B
)*op(sub(
A
))
.
uplo
(global) Specifies whether the distributed matrix
sub(
A
)
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.
transa
(global) Specifies the form of
op(sub(
A
))
used in the matrix multiplication:
if
transa
= '
N
'
or
'
n
'
, then
op(sub(
A
)) = sub(
A
)
;
if
transa
= '
T
'
or
'
t
'
, then
op(sub(
A
)) = sub(
A
)'
;
if
transa
= '
C
'
or
'
c
'
, then
op(sub(
A
)) = conjg(sub(
A
)')
.
diag
(global) Specifies whether the matrix
sub(
A
)
is unit triangular:
if
diag
=
'U'
or
'u'
then the matrix is unit triangular;
if
diag
=
'N'
or
'n'
, then the matrix is not unit triangular.
m
(global) Specifies the number of rows of the distributed matrix
sub(
B
)
,
m
0.
n
(global) Specifies the number of columns of the distributed matrix
sub(
B
)
,
n
0.
alpha
(global)
Specifies the scalar
alpha
.
When
alpha
is zero, then the array
b
need not be set before entry.
a
(local)
Array, size
lld_a
by
ka
, where
ka
is at least
LOCq(1,
ja
+
m
-1)
when
side
=
'L'
or
'l'
and is at least
LOCq(1,
ja
+
n
-1)
when
side
=
'R'
or
'r'
.
Before entry with
uplo
=
'U'
or
'u'
, this array contains the local entries corresponding to the entries of the upper triangular distributed matrix
sub(
A
)
, and the local entries corresponding to the entries of the strictly lower triangular part of the distributed matrix
sub(
A
)
is not referenced.
Before entry with
uplo
=
'L'
or
'l'
, this array contains the local entries corresponding to the entries of the lower triangular distributed matrix
sub(
A
)
, and the local entries corresponding to the entries of the strictly upper triangular part of the distributed matrix
sub(
A
)
is not referenced .
When
diag
=
'U'
or
'u'
, the local entries corresponding to the diagonal elements of the submatrix
sub(
A
)
are not referenced either, but are assumed to be unity.
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(1,
jb
+
n
-1)
).
Before entry, this array contains 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
.
Output Parameters
b
Overwritten by the transformed distributed matrix.

#### Product and Performance Information

1

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