Developer Reference

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

p?orgqr

Generates the orthogonal matrix
Q
of the
QR
factorization formed by
p?geqrf
.

Syntax

call psorgqr
(
m
,
n
,
k
,
a
,
ia
,
ja
,
desca
,
tau
,
work
,
lwork
,
info
)
call pdorgqr
(
m
,
n
,
k
,
a
,
ia
,
ja
,
desca
,
tau
,
work
,
lwork
,
info
)
Include Files
Description
The
p?orgqr
routine
generates the whole or part of
m
-by-
n
real distributed matrix
Q
denoting
A
(
ia
:
ia
+
m
-1,
ja
:
ja
+
n
-1) with orthonormal columns, which is defined as the first
n
columns of a product of
k
elementary reflectors of order
m
Q
=
H
(1)*
H
(2)*...*
H
(
k
)
as returned by
p?geqrf
.
Input Parameters
m
(global)
INTEGER
.
The number of rows in the matrix sub(
Q
)
(
m
0)
.
n
(global)
INTEGER
.
The number of columns in the matrix sub(
Q
)
(
m
n
0)
.
k
(global)
INTEGER
.
The number of elementary reflectors whose product defines the matrix
Q
(
n
k
0)
.
a
(local)
REAL
for
psorgqr
DOUBLE PRECISION
for
pdorgqr
Pointer into the local memory to an array of local size
(
lld_a
,
LOCc
(
ja
+
n
-1))
. The
j
-th column must contain the vector that defines the elementary reflector
H
(
j
),
ja
j
ja
+
k
-1, as returned by
p?geqrf
in the
k
columns of its distributed matrix argument
A
(
ia
:*,
ja
:
ja
+
k
-1).
ia
,
ja
(global)
INTEGER
.
The row and column indices in the global matrix
A
indicating the first row and the first column of the submatrix
A
(
ia
:
ia
+
m
-1,
ja
:
ja
+
n
-1), respectively.
desca
(global and local)
INTEGER
array of size
dlen_
. The array descriptor for the distributed matrix
A
.
tau
(local)
REAL
for
psorgqr
DOUBLE PRECISION
for
pdorgqr
Array of size
LOCc
(
ja
+
k
-1)
.
Contains the scalar factor
tau
(
j
)
of elementary reflectors
H
(
j
)
as returned by
p?geqrf
.
tau
is tied to the distributed matrix
A
.
work
(local)
REAL
for
psorgqr
DOUBLE PRECISION
for
pdorgqr
Workspace array of size of
lwork
.
lwork
(local or global)
INTEGER
,
size of
work
.
Must be at least
lwork
nb_a
*(
nqa