Developer Reference

  • 2021.1
  • 12/04/2020
  • Public Content
Contents

?ormqr

Multiplies a real matrix by the orthogonal matrix Q of the QR factorization formed by
?geqrf
or
?geqpf
.

Syntax

lapack_int
LAPACKE_sormqr
(
int
matrix_layout
,
char
side
,
char
trans
,
lapack_int
m
,
lapack_int
n
,
lapack_int
k
,
const
float
*
a
,
lapack_int
lda
,
const
float
*
tau
,
float
*
c
,
lapack_int
ldc
);
lapack_int
LAPACKE_dormqr
(
int
matrix_layout
,
char
side
,
char
trans
,
lapack_int
m
,
lapack_int
n
,
lapack_int
k
,
const
double
*
a
,
lapack_int
lda
,
const
double
*
tau
,
double
*
c
,
lapack_int
ldc
);
Include Files
  • mkl.h
Description
The routine multiplies a real matrix
C
by
Q
or
Q
T
, where
Q
is the orthogonal matrix
Q
of the
QR
factorization formed by the routine
?geqrf
or ?geqpf
.
Depending on the parameters
side
left_right
and
trans
, the routine can form one of the matrix products
Q
*
C
,
Q
T
*
C
,
C
*
Q
, or
C
*
Q
T
(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
T
is applied to
C
from the left.
If
side
='R'
,
Q
or
Q
T
is applied to
C
from the right.
trans
Must be either
'N'
or
'T'
.
If
trans
='N'
, the routine multiplies
C
by
Q
.
If
trans
='T'
, the routine multiplies
C
by
Q
T
.
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
,
tau
,
c
Arrays:
a
and
tau
are the arrays returned by
sgeqrf
/
dgeqrf
or
sgeqpf
/
dgeqpf
.
The size of
a
is max(1,
lda
*
k
) for column major layout, max(1,
lda
*
m
) for row major layout and
side
= 'L', and max(1,
lda
*
n
) for row major layout and
side
= 'R'.
The size of
tau
must be at least max(1,
k
).
Array
c
of 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
The leading dimension of
a
. Constraints:
if
side
=
'L'
,
lda
max(1,
m
)
for column major layout and max(1,
k
) for row major layout
;
if
side
=
'R'
,
lda
max(1,
n
)
for column major layout and max(1,
k
) for row major layout
.
ldc
The leading dimension of
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
T
*
C
,
C
*
Q
, or
C
*
Q
T
(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 complex counterpart of this routine is unmqr.

Product and Performance Information

1

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