## Developer Reference

• 0.10
• 10/21/2020
• Public Content
Contents

# cblas_?trmm

Computes a matrix-matrix product where one input matrix is triangular.

## Syntax

Include Files
• mkl.h
Description
The
?trmm
routines compute a scalar-matrix-matrix product
with one triangular matrix
. The operation is defined as
`B := alpha*op(A)*B`
or
`B := alpha*B*op(A)`
where:
alpha
is a scalar,
B
is an
m
-by-
n
matrix,
A
is a unit, or non-unit, upper or lower triangular matrix
op(
A
)
is one of
op(
A
)
=
A
, or
op(A) =
A
'
, or
op(
A
) = conjg(
A
')
.
Input Parameters
Layout
Specifies whether two-dimensional array storage is row-major (
CblasRowMajor
) or column-major (
CblasColMajor
).
side
Specifies whether
op(
A
)
appears on the left or right of
B
in the operation:
if
side
=
CblasLeft
, then
B
:=
alpha
*op(
A
)*
B
;
if
side
=
CblasRight
, then
B
:=
alpha
*
B
*op(
A
)
.
uplo
Specifies whether the matrix
A
is upper or lower triangular.
uplo
=
CblasUpper
if
uplo
=
CblasLower
, then the matrix is low triangular.
transa
Specifies the form of
op(
A
)
used in the matrix multiplication:
if
transa
=
CblasNoTrans
, then
op(
A
) =
A
;
if
transa
=
CblasTrans
, then
op(
A
) =
A
'
;
if
transa
=
CblasConjTrans
, then
op(
A
) = conjg(
A
')
.
diag
Specifies whether the matrix
A
is unit triangular:
if
diag
=
CblasUnit
then the matrix is unit triangular;
if
diag
=
CblasNonUnit
, then the matrix is not unit triangular.
m
Specifies the number of rows of
B
. The value of
m
must be at least zero.
n
Specifies the number of columns of
B
. The value of
n
must be at least zero.
alpha
Specifies the scalar
alpha
.
When
alpha
is zero, then
a
is not referenced and
b
need not be set before entry.
a
Array, size
lda
by
k
, where
k
is
m
when
side
=
CblasLeft
and is
n
when
side
=
CblasRight
. Before entry with
uplo
=
CblasUpper
k
by
k
upper triangular part of the array
a
must contain the upper triangular matrix and the strictly lower triangular part of
a
is not referenced.
Before entry with
uplo
=
CblasLower
k
by
k
lower triangular part of the array
a
must contain the lower triangular matrix and the strictly upper triangular part of
a
is not referenced.
When
diag
=
CblasUnit
, the diagonal elements of
a
are not referenced either, but are assumed to be unity.
lda
a
as declared in the calling (sub)program. When
side
=
CblasLeft
, then
lda
must be at least
max(1,
m
)
, when
side
=
CblasRight
, then
lda
must be at least
max(1,
n
)
.
b
For
Layout
=
CblasColMajor
: array, size
ldb
*
n
m
-by-
n
part of the array
b
must contain the matrix
B
.
For
Layout
=
CblasRowMajor
: array, size
ldb
*
m
n
-by-
m
part of the array
b
must contain the matrix
B
.
ldb
b
as declared in the calling (sub)program.
When
Layout
=
CblasColMajor
,
ldb
must be at least
max(1,
m
)
; otherwise,
ldb
must be at least
max(1,
n
)
.
Output Parameters
b
Overwritten by the transformed 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