EIGVSAVE

Subcase Information Entry The EIGVSAVE command can be used to output eigenvalue and eigenvector results of a Normal Modes Analysis to an external data file (.eigv).

Format

EIGVSAVE = integer

Definitions

Argument Options Description
integer <integer>

No default

 Outputs eigenvalues and eigenvectors obtained from a normal modes analysis to an external data file.

The external eigenvalue data file name is of the form:

<prefix>.#.eigv

Where,
<prefix>
Is defined by the EIGVNAME I/O Options Entry.
#
The integer argument defined. 4

Comments

  1. Only one occurrence of EIGVSAVE per subcase is permitted.
  2. If EIGVSAVE is not present, eigenvalue and eigenvector results do not get exported to an external data file.
  3. EIGVSAVE is not supported for fluid elements.
  4. The integer argument specified here is used as part of the name of the .eigv file as:

    In an input file named testfile.fem, if EIGVSAVE=50 is specified, without EIGVNAME entry, then the eigenvalue and eigenvector results are exported to the testfile.50.eigv file. You can see that the input file name is used as the default file name for the .eigv file when the EIGVNAME entry is not specified.

  5. There are several scenarios under which EIGSAVE and EIGVRETRIEVE can be used:
    • Saving the eigenvector for the full model (using DISP = ALL) in the EIGVSAVE run and then retrieving for the full model (or a subset) in the EIGVRETRIEVE run (using DISP = ALL).
    • Saving the eigenvector for only a part of the model (using DISP = SET ID) in the EIGVSAVE run and then retrieving for the same (or a subset) part of the model (using DISP = SET ID) in the EIGVRETRIEVE run. Saving partial eigenvector in EIGVSAVE run is only valid if the run with EIGVRETRIEVE is a Modal Transient analysis.

    The Degrees of Freedom (DoF) to be retrieved by EIGVRETRIEVE must be the same as or a subset of the DoF provided by corresponding EIGVSAVE entry.

  6. In the case of Modal Transient Analysis
    • If full-model eigenvector is saved and retrieved, EIGVRETRIEVE can be used with Lanczos (EIGRL), AMSES (EIGRA), and AMLS eigen solvers.
    • If partial-model eigenvector is retrieved, EIGVRETRIEVE can be used only with AMSES (EIGRA) and AMLS eigen solvers.

    In the case of Modal Frequency Response Analysis, EIGVRETRIEVE can only be used with the Lanczos eigen solver. Otherwise, an error message will be printed.

    Although an eigen solver is not involved in the EIGVRETRIEVE run, these restrictions are for syntactical reasons.