## Developer Reference

• 0.9
• 09/09/2020
• Public Content
Contents

# p?potf2

Computes the Cholesky factorization of a symmetric/Hermitian positive definite matrix (local unblocked algorithm).

## Syntax

Include Files
• mkl_scalapack.h
Description
The
p?potf2
function
computes the Cholesky factorization of a real symmetric or complex Hermitian positive definite distributed matrix sub
(
A
)=
A
(
ia
:
ia
+
n
-1,
ja
:
ja
+
n
-1)
.
The factorization has the form
sub(
A
) =
U'
*
U
, if
uplo
=
'U'
, or sub(
A
) =
L
*
L'
, if
uplo
=
'L'
,
where
U
is an upper triangular matrix,
L
is lower triangular.
X'
denotes transpose (conjugate transpose) of
X
.
Input Parameters
uplo
(global)
Specifies whether the upper or lower triangular part of the symmetric/Hermitian matrix
A
is stored.
=
'U'
: upper triangle of sub (
A
) is stored;
=
'L'
: lower triangle of sub (
A
) is stored.
n
(global)
The number of rows and columns to be operated on, that is, the order of the distributed matrix sub (
A
).
n
0
.
a
(local)
Pointer into the local memory to an array of size
lld_a
*
LOCc
(
ja
+
n
-1)
containing the local pieces of the
n
-by-
n
symmetric distributed matrix sub(
A
) to be factored.
If
uplo
=
'U'
n
-by-
n
upper triangular part of sub(
A
) contains the upper triangular matrix and the strictly lower triangular part of this matrix is not referenced.
If
uplo
=
'L'
n
-by-
n
lower triangular part of sub(
A
) contains the lower triangular matrix and the strictly upper triangular part of sub(
A
) is not referenced.
ia
,
ja
(global)
The row and column indices in the global matrix
A
indicating the first row and the first column of the sub(
A
), respectively.
desca
(global and local) array of size
dlen_
. The array descriptor for the distributed matrix
A
.
Output Parameters
a
(local)
On exit,
if
uplo
=
'U'
, the upper triangular part of the distributed matrix contains the Cholesky factor
U
;
if
uplo
=
'L'
, the lower triangular part of the distributed matrix contains the Cholesky factor
L
.
info
(local)
= 0
: successful exit
< 0
: if the
i
-th argument is an array and the
j
-th entry
, indexed
j
-1,
then
info
= - (
i
*100 +
j
),
if the
i
-th argument is a scalar and had an illegal value,
then
info
= -
i
.
>
0
: if
info
=
k
, the leading minor of order
k
is not positive definite, and the factorization could not be completed.

#### Product and Performance Information

1

Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804