Contents

# ?unmqr

Multiplies a complex matrix by the unitary matrix Q of the QR factorization formed by
?geqrf
.

## Syntax

Include Files
• mkl.h
Description
The routine multiplies a rectangular complex matrix
C
by
Q
or
Q
H
, where
Q
is the unitary matrix
Q
of the
QR
factorization formed by the routines
?geqrf
or geqpf
.
Depending on the parameters
side
and
trans
, the routine can form one of the matrix products
Q*C
,
Q
H
*C
,
C*Q
, or
C*Q
H
(overwriting the result on
C
).
Input Parameters
matrix_layout
Specifies whether matrix storage layout is row major (
LAPACK_ROW_MAJOR
) or column major (
LAPACK_COL_MAJOR
).
side
Must be either
'L'
or
'R'
.
If
side
=
'L'
,
Q
or
Q
H
is applied to
C
from the left.
If
side
=
'R'
,
Q
or
Q
H
is applied to
C
from the right.
trans
Must be either
'N'
or
'C'
.
If
trans
=
'N'
, the routine multiplies
C
by
Q
.
If
trans
=
'C'
, the routine multiplies
C
by
Q
H
.
m
The number of rows in the matrix
C
(
m
0
).
n
The number of columns in
C
(
n
0
).
k
The number of elementary reflectors whose product defines the matrix
Q
. Constraints:
0
k
m
if
side
=
'L'
;
0
k
n
if
side
=
'R'
.
a
,
c
,
tau
Arrays:
a
size max(1,
lda
*
k
) for column major layout, max(1,
lda
*
m
) for row major layout when
side
='L', and max(1,
lda
*
n
) for row major layout when side ='R'
and
tau
are the arrays returned by
cgeqrf
/
zgeqrf
or
cgeqpf
/
zgeqpf
.
The size of
tau
must be at least max(1,
k
).
c
(size max(1,
ldc
*
n
) for column major layout and max(1,
ldc
*
m
for row major layout)
contains the
m
-by-
n
matrix
C
.
lda
a
. Constraints:
lda
max(1,
m
)
for column major layout and
lda
max(1,
k
) for row major layout
if
side
=
'L'
;
lda
max(1,
n
)
for column major layout and
lda
max(1,
k
) for row major layout
if
side
=
'R'
.
ldc
c
. Constraint:
ldc
max(1,
m
)
for column major layout and max(1,
n
) for row major layout
.
Output Parameters
c
Overwritten by the product
Q*C
,
Q
H
*C
,
C*Q
, or
C*Q
H
(as specified by
side
and
trans
).
Return Values
This function returns a value
info
.
If
info
=0
, the execution is successful.
If
info
=
-i
, the
i
-th parameter had an illegal value.
Application Notes
The real counterpart of this routine is ormqr.

#### 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