## Developer Reference

• 2020.2
• 07/15/2020
• Public Content
Contents

# ?trmv

Computes a matrix-vector product using a triangular matrix.

## Syntax

Include Files
• mkl.fi
,
blas.f90
Description
The
?trmv
routines perform one of the following matrix-vector operations defined as
x
:=
A
*
x
, or
x
:= A'*
x
, or
x
:= conjg(
A
')*
x
,
where:
x
is an
n
-element vector,
A
is an
n
-by-
n
unit, or non-unit, upper or lower triangular matrix.
Input Parameters
uplo
CHARACTER*1
.
Specifies whether the matrix
A
is upper or lower triangular:
uplo
=
'U'
or
'u'
if
uplo
=
'L'
or
'l'
, then the matrix is low triangular.
trans
CHARACTER*1
.
Specifies the operation:
if
trans
= 'N'
or
'n'
, then
x
:=
A
*
x
;
if
trans
= 'T'
or
't'
, then
x
:=
A
'*
x
;
if
trans
= 'C'
or
'c'
, then
x
:= conjg(
A
')*
x
.
diag
CHARACTER*1
.
Specifies whether the matrix
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.
n
INTEGER
.
Specifies the order of the matrix
A
. The value of
n
must be at least zero.
a
REAL
for
strmv
DOUBLE PRECISION
for
dtrmv
COMPLEX
for
ctrmv
DOUBLE COMPLEX
for
ztrmv
Array, size
(
lda
,
n
)
. Before entry with
uplo
=
'U'
or
'u'
n
-by-
n
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
=
'L'
or
'l'