Developer Reference

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

p?latrz

Reduces an upper trapezoidal matrix to upper triangular form by means of orthogonal/unitary transformations.

Syntax

call pslatrz
(
m
,
n
,
l
,
a
,
ia
,
ja
,
desca
,
tau
,
work
)
call pdlatrz
(
m
,
n
,
l
,
a
,
ia
,
ja
,
desca
,
tau
,
work
)
call pclatrz
(
m
,
n
,
l
,
a
,
ia
,
ja
,
desca
,
tau
,
work
)
call pzlatrz
(
m
,
n
,
l
,
a
,
ia
,
ja
,
desca
,
tau
,
work
)
Description
The
p?latrz
routine
reduces the
m
-by-
n
(
m
n
)
real/complex upper trapezoidal matrix
sub(
A
) = [
A
(
ia
:
ia
+
m
-1,
ja
:
ja
+
m
-1)
A
(
ia
:
ia
+
m
-1,
ja
+
n-l
:
ja
+
n
-1)]
to upper triangular form by means of orthogonal/unitary transformations.
The upper trapezoidal matrix sub(
A
) is factored as
sub(
A
) = (
R
0 )*
Z
,
where
Z
is an
n
-by-
n
orthogonal/unitary matrix and
R
is an
m
-by
-
m
upper triangular matrix.
Input Parameters
m
(global)
INTEGER
.
The number of rows in the distributed matrix sub(
A
).
m
0
.
n
(global)
INTEGER
.
The number of columns in the distributed matrix sub(
A
).
n
0
.
l
(global)
INTEGER
.
The number of columns of the distributed matrix sub(
A
) containing the meaningful part of the Householder reflectors.
l
>
0
.
a
(local)
REAL
for
pslatrz
DOUBLE PRECISION
for
pdlatrz
COMPLEX
for
pclatrz
COMPLEX*16
for
pzlatrz
.
Pointer into the local memory to an array of size
(
lld_a
,
LOCc
(
ja
+
n
-1))
. On entry, the local pieces of the
m
-by-
n
distributed matrix sub(
A
), which is to be factored.
ia
(global)
INTEGER
.
The row index in the global matrix
A
indicating the first row of sub(
A
).
ja
(global)
INTEGER
.
The column index in the global matrix
A
indicating the first column of sub(
A
).
desca
(global and local)
INTEGER
array of size
dlen_
.
The array descriptor for the distributed matrix
A
.
work
(local)
REAL
for
pslatrz
DOUBLE PRECISION
for
pdlatrz
COMPLEX
for
pclatrz
COMPLEX*16
for
pzlatrz
.
Workspace array of size
lwork
.
lwork
nq
0 + max(1,
mp
0)
, where
iroff
= mod(
ia
-1,
mb_a
),
icoff
= mod(
ja
-1,