Developer Reference

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

pardiso iparm Parameter

This table describes all individual components of the
Intel® MKL
PARDISO
iparm
parameter. Components which are not used must be initialized with 0. Default values are denoted with an asterisk (*).
Component
Description
iparm
(1)
input
Use default values.
0
iparm
(2)
-
iparm
(64)
are filled with default values.
0
You must supply all values in components
iparm
(2)
-
iparm
(64)
.
iparm
(2)
input
Fill-in reducing ordering for the input matrix.
You can control the parallel execution of the solver by explicitly setting the
MKL_NUM_THREADS
environment variable. If fewer OpenMP threads are available than specified, the execution may slow down instead of speeding up. If
MKL_NUM_THREADS
is not defined, then the solver uses all available processors.
0
The minimum degree algorithm [Li99] .
2*
The nested dissection algorithm from the METIS package [Karypis98] .
3
The parallel (OpenMP) version of the nested dissection algorithm. It can decrease the time of computations on multi-core computers, especially when
Intel® MKL
PARDISO Phase 1 takes significant time.
Setting
iparm
(2)
= 3
prevents the use of CNR mode (
iparm
(34)
> 0
) because
Intel® MKL
PARDISO uses dynamic parallelism.
iparm
(3)
Reserved. Set to zero.
iparm
(4)
input
Preconditioned CGS/CG.
This parameter controls preconditioned CGS [Sonn89] for nonsymmetric or structurally symmetric matrices and Conjugate-Gradients for symmetric matrices.
iparm
(4)
has the form
iparm
(4)
=
10*
L
+
K
.
K
=0
The factorization is always computed as required by
phase
.
K
=1
CGS iteration replaces the computation of
LU
. The preconditioner is
LU
that was computed at a previous step (the first step or last step with a failure) in a sequence of solutions needed for identical sparsity patterns.
K
=2
CGS iteration for symmetric positive definite matrices replaces the computation of
LL
T
. The preconditioner is
LL
T
that was computed at a previous step (the first step or last step with a failure) in a sequence of solutions needed for identical sparsity patterns.
The value
L
controls the stopping criterion of the Krylov Subspace iteration:
eps
CGS
= 10
-L
is used in the stopping criterion
||
dx
i
|| / ||
dx
0
|| < eps
CGS
where
||
dx
i
|| = ||inv(
L
*
U
)*
r
i
||
for
K
= 1
or
||
dx
i
|| = ||inv(
L
*
L
T
)*
r
i
||
for
K
= 2
and
r
<