KRYOPT
KRYOPT, MAXDIM
,
--
,--
,
RESTOL
, OrthTol
Specifies solution options for a Krylov method harmonic analysis.
MAXDIM
Maximum dimension of subspace. The default size is automatically determined by the program (ranges around 50).
-
--
,--
Unused fields.
RESTOL
Tolerance used to verify the L-2 norm values of calculated residuals and issue a warning if
RESTOL
is exceeded throughout the entire frequency range. Default = 0.05.OrthTol
Tolerance that controls the orthonormality check of the Krylov subspace vectors. Valid values range from 0 to 1. The default is 1E-8.
Notes
This command is used to specify solution options for a harmonic analysis solved with the
Krylov method (Method
= KRYLOV on HROPT, see
also Frequency-Sweep Harmonic Analysis via the Krylov Method in the Structural Analysis Guide).
Increasing subspace size (MAXDIM
) improves solution accuracy
with the trade-off of increased computational cost and additional memory requirements.
The RESTOL
and
OrthTol
options do not affect the accuracy of the solution. They
simply control the output of messages displayed regarding the accuracy of the final computed
solution or orthonormality of the computed subspace.
The program computes the condition number of a matrix created based on the dot products of
the Krylov subspace vectors with each other. When the condition number of this matrix is
closer to 1, it means the subspace vectors are orthonormal. When it is closer to 0, that means
the subspace vectors are not orthonormal. The OrthTol
value is used
in the following formula to determine the orthonormality of the computed Krylov subspace: . When this condition is true, the Krylov subspace is determined to be
sufficiently orthonormal, and vice versa.