## Developer Reference

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

# p?lauum

Computes the product
U
*
U
'
or
L
'*
L
, where
U
and
L
are upper or lower triangular matrices.

## Syntax

Description
The
p?lauum
routine
computes the product
U*U
' or
L'*L
, where the triangular factor
U
or
L
is stored in the upper or lower triangular part of the matrix sub
(
A
)=
A
(
ia
:
ia
+
n
-1,
ja
:
ja
+
n
-1)
.
If
uplo
=
'U'
or
'u'
, then the upper triangle of the result is stored, overwriting the factor
U
in sub(
A
). If
uplo
=
'L'
or
'l'
, then the lower triangle of the result is stored, overwriting the factor
L
in sub(
A
).
This is the blocked form of the algorithm, calling Level 3 PBLAS.
Input Parameters
uplo
(global)
CHARACTER*1
.
Specifies whether the triangular factor stored in the matrix sub(
A
) is upper or lower triangular:
=
'U'
: upper triangular
=
'L'
: lower triangular.
n
(global)
INTEGER
.
The number of rows and columns to be operated on, that is, the order of the triangular factor
U
or
L
.
n
0
.
a
(local)
REAL
for
pslauum
DOUBLE PRECISION
for
pdlauum
COMPLEX
for
pclauum
COMPLEX*16
for
pzlauum
.
Pointer into the local memory to an array of size
(
lld_a
,
LOCc
(
ja
+
n
-1))
. On entry, the local pieces of the triangular factor
U
or
L
.
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
.
Output Parameters
a
(local)
On exit, if
uplo
=
'U'
, the upper triangle of the distributed matrix sub(
A
) is overwritten with the upper triangle of the product
U*U
' ; if
uplo
=
'L'
, the lower triangle of sub(
A
) is overwritten with the lower triangle of the product
L
'*
L
.