Developer Reference

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

p?dttrf

Computes the
LU
factorization of a diagonally dominant-like tridiagonal distributed matrix.

Syntax

call psdttrf
(
n
,
dl
,
d
,
du
,
ja
,
desca
,
af
,
laf
,
work
,
lwork
,
info
)
call pddttrf
(
n
,
dl
,
d
,
du
,
ja
,
desca
,
af
,
laf
,
work
,
lwork
,
info
)
call pcdttrf
(
n
,
dl
,
d
,
du
,
ja
,
desca
,
af
,
laf
,
work
,
lwork
,
info
)
call pzdttrf
(
n
,
dl
,
d
,
du
,
ja
,
desca
,
af
,
laf
,
work
,
lwork
,
info
)
Include Files
Description
The
p?dttrf
routine
computes the
LU
factorization of an
n
-by-
n
real/complex diagonally dominant-like tridiagonal distributed matrix
A
(1:
n
,
ja
:
ja
+
n
-1) without pivoting for stability.
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*L*U*P
T
,
where
P
is a permutation matrix, and
L
and
U
are banded lower and upper 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
n
(global)
INTEGER
.
The number of rows and columns to be operated on, that is, the order of the distributed submatrix
A
(1:
n
,
ja
:
ja
+
n
-1)
(
n
0)
.
dl
,
d
,
du
(local)
REAL
for
pspttrf
DOUBLE PRECISON
for
pdpttrf
COMPLEX
for
pcpttrf
DOUBLE COMPLEX
for
pzpttrf
.
Pointers to the local arrays of size
nb_a
each.
On entry, the array
dl
contains the local part of the global vector storing the subdiagonal elements of the matrix. Globally,
dl
(1)
is not referenced, and