Developer Reference

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

p?pbtrf

Computes the Cholesky factorization of a symmetric (Hermitian) positive-definite banded distributed matrix.

Syntax

call pspbtrf
(
uplo
,
n
,
bw
,
a
,
ja
,
desca
,
af
,
laf
,
work
,
lwork
,
info
)
call pdpbtrf
(
uplo
,
n
,
bw
,
a
,
ja
,
desca
,
af
,
laf
,
work
,
lwork
,
info
)
call pcpbtrf
(
uplo
,
n
,
bw
,
a
,
ja
,
desca
,
af
,
laf
,
work
,
lwork
,
info
)
call pzpbtrf
(
uplo
,
n
,
bw
,
a
,
ja
,
desca
,
af
,
laf
,
work
,
lwork
,
info
)
Include Files
Description
The
p?pbtrf
routine
computes the Cholesky factorization of an
n
-by-
n
real symmetric or complex Hermitian positive-definite banded distributed matrix
A
(1:
n
,
ja
:
ja
+
n
-1).
The resulting factorization is not the same factorization as returned from LAPACK. Additional permutations are performed on the matrix for the sake of parallelism.
The factorization has the form:
A
(1:
n
,
ja
:
ja
+
n
-1) =
P
*
U
H
*
U
*
P
T
, if
uplo
=
'U'
, or
A
(1:
n
,
ja
:
ja
+
n
-1) =
P*L*L
H
*P
T
, if
uplo
=
'L'
,
where
P
is a permutation matrix and
U
and
L
are banded upper and lower triangular matrices, respectively.
Optimization Notice
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
This notice covers the following instruction sets: SSE2, SSE4.2, AVX2, AVX-512.
Input Parameters
uplo
(global)
CHARACTER*1
.
Must be
'U'
or
'L'
.
If
uplo
=
'U'
, upper triangle of
A
(1:
n
,
ja
:
ja
+
n
-1) is stored;
If
uplo
=