DAMPOPT

DAMPOPT, Option, Value
Sets damped eigensolver options.

SOLUTION: Dynamic Options

Option

Damped eigensolver option:

SHIFT

—

Activate or deactivate the shift strategy of the damped eigensolver to move to a frequency range of interest. The FREQB value of the MODOPT command is used to choose the first frequency shift (see notes for details).

Valid input for Value when Option = SHIFT:

OFF	—	Do not activate the shift strategy (default).
ON	—	Activate the shift strategy.

MEMORY

—

Controls the memory allocation strategy for the Damped eigensolver.

Valid input for Value when Option = MEMORY:

DEFAULT	—	Default memory configuration (default). Everything is determined dynamically with respect to current machine resources.
INCORE	—	Fully in-core memory configuration.
MIX1	—	First level of mixed in-core / out-of-core configuration.
MIX2	—	Second level of mixed in-core / out-of-core configuration.
OUTOFCORE	—	Fully out-of-core memory configuration.

Value

Assigned value for the specified Option (as described above).

Command Default

By default, the shift strategy is not activated for the damped eigensolver. This ensures a faster solve process but limits the number of eigenvalues that can be found.

The default memory allocation strategy is used. Mechanical APDL evaluates the resources of the machine to choose the in-core or out-of-core mode.

Notes

DAMPOPT specifies options to be used with the damped eigensolver (MODOPT,DAMP) during a modal analysis (ANTYPE,MODAL).

Activating the shift strategy (Option = SHIFT and Value = ON) enables the eigensolver to find higher frequency eigenvalues that might otherwise be missed. The SHIFT option has two objectives:

Extract high frequency eigenvalues according to the FREQB argument specified with MODOPT.
Unlock an auto-shift feature, so the algorithm will chain several analyses automatically then aggregate the solutions in one single results set.

If FREQE is specified on MODOPT, the specified value is used to filter the complex eigenfrequencies based on magnitude.

When the shift strategy is activated (DAMPOPT,SHIFT,ON)

and FREQB on MODOPT is specified, the damped eigensolver only produces eigenfrequencies with a real part greater than FREQB
and FREQB on MODOPT is not specified, the damped eigensolver finds eigenvalues closest to the 0 Hz point.

Memory Allocation Option (Option = MEMORY)

The damped eigensolver algorithm allocates two main pools of memory:

Memory for the internal damped eigensolver iterations.
Memory for the specific damped eigensolver working arrays.

The following table shows how memory is allocated for each option.

`Value` (`Option` = MEMORY)	Damped Eigensolver	Working Arrays
INCORE	In-Core	In-Core
MIX1	In-Core	Out-of-Core
MIX2	Out-of-Core	In-Core
OUTOFCORE	Out-of-Core	Out-of-Core

The MIX1 configuration typically uses more memory than the MIX2 configuration, except when a large number of modes are requested for a small model.

Example Usage

Example: Shift Option Usage on DAMPOPT in the Structural Analysis Guide

Menu Paths

This command cannot be accessed from a menu.