Developer Reference

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

?org2l/?ung2l

Generates all or part of the orthogonal/unitary matrix Q from a QL factorization determined by
?geqlf
(unblocked algorithm).

Syntax

call sorg2l
(
m
,
n
,
k
,
a
,
lda
,
tau
,
work
,
info
)
call dorg2l
(
m
,
n
,
k
,
a
,
lda
,
tau
,
work
,
info
)
call cung2l
(
m
,
n
,
k
,
a
,
lda
,
tau
,
work
,
info
)
call zung2l
(
m
,
n
,
k
,
a
,
lda
,
tau
,
work
,
info
)
Include Files
  • mkl.fi
Description
The routine
?org2l
/
?ung2l
generates an
m
-by-
n
real/complex matrix
Q
with orthonormal columns, which is defined as the last
n
columns of a product of
k
elementary reflectors of order
m
:
Q
=
H
(
k
)*...*
H
(2)*
H
(1)
as returned by
?geqlf
.
Input Parameters
m
INTEGER
. The number of rows of the matrix
Q
.
m
0
.
n
INTEGER
. The number of columns of the matrix
Q
.
m
n
0
.
k
INTEGER
. The number of elementary reflectors whose product defines the matrix
Q
.
n
k
0
.
a
REAL
for
sorg2l
DOUBLE PRECISION
for
dorg2l
COMPLEX
for
cung2l
DOUBLE COMPLEX
for
zung2l
.
Array,
DIMENSION
(
lda
,
n
).
On entry, the (
n
-k
+
i
)-th column must contain the vector which defines the elementary reflector
H
(
i
), for
i
= 1,2,...,
k
, as returned by
?geqlf
in the last
k
columns of its array argument
A
.
lda
INTEGER
. The leading dimension of the array
a
.
lda
max(1,
m
)
.
tau
REAL
for
sorg2l
DOUBLE PRECISION
for
dorg2l
COMPLEX
for
cung2l
DOUBLE COMPLEX
for
zung2l
.
Array,
DIMENSION
(
k
).
tau
(
i
) must contain the scalar factor of the elementary reflector
H
(
i
), as returned by
?geqlf
.
work
REAL
for
sorg2l
DOUBLE PRECISION
for
dorg2l
COMPLEX
for
cung2l
DOUBLE COMPLEX
for
zung2l
.
Workspace array,
DIMENSION
(
n
).
Output Parameters
a
On exit, the
m
-by-
n
matrix
Q
.
info
INTEGER
.
= 0: successful exit
< 0: if
info
= -
i
, the
i
-th argument has an illegal value