## Developer Reference

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

# p?posv

Solves a symmetric positive definite system of linear equations.

## Syntax

Include Files
Description
The
p?posv
routine
computes the solution to a real/complex system of linear equations
sub(
A
)*
X
= sub(
B
)
,
where sub(
A
) denotes
A
(
ia
:
ia
+
n
-1,
ja
:
ja
+
n
-1)
and is an
n-
by-
n
symmetric/Hermitian distributed positive definite matrix and
X
and sub(
B
) denoting
B
(
ib
:
ib
+
n
-1,
jb
:
jb
+
nrhs
-1)
are
n
-by-
nrhs
distributed matrices. The Cholesky decomposition is used to factor sub(
A
) as
sub(
A
) =
U
T
*
U
, if
uplo
= 'U'
, or
sub(
A
) =
L
*
L
T
, if
uplo
= 'L'
,
where
U
is an upper triangular matrix and
L
is a lower triangular matrix. The factored form of sub(
A
) is then used to solve the system of equations.
Input Parameters
uplo
(global)
CHARACTER
.
Must be
'U'
or
'L'
.
Indicates whether the upper or lower triangular part of sub(
A
) is stored.
n
(global)
INTEGER
.
The order of the distributed matrix sub(
A
)
(
n
0)
.
nrhs
INTEGER
.
The number of right-hand sides; the number of columns of the distributed matrix sub(
B
)
(
nrhs
0)
.
a
(local)
REAL
for
psposv
DOUBLE PRECISION