Complex Eigenvalue Extraction Data
Description: Defines data needed to perform complex eigenvalue analysis.
Format:
Example:
| Field | Definition | Type | Default | ||||
|---|---|---|---|---|---|---|---|
| SID | Set identification number. | Integer > 0 | Required | ||||
| METHOD | Method of complex eigenvalue extraction, one of the following character variables: ARNO, HESS, or CLAN. See Remark 2. | Character | ARNO | ||||
| NORM | Method for normalizing eigenvectors, one of the following character variables: MAX or POINT
|
Character | MAX | ||||
| G | Grid point identification number. | Integer > 0 | Required for NORM = POINT | ||||
| C | Component number of global coordinate. | 1 ≤ Integer ≤ 6 | Required for NORM = POINT | ||||
| CTOL | Eigenvalue convergence tolerance. | Real or blank | 1.0E-6 | ||||
| ND | Number of roots desired. | Integer > 0 | Required | ||||
| NIVEC | Number of additional iteration vectors. | Integer > 0 | 9 | ||||
| MAXITER | Maximum number of iterations. | Integer > 0 | 100 | ||||
| XC | Extraction criteria, one of the following character variables: LM, SM, LR, SR, LI, SI or AUTO. See Remark 3. | Character | AUTO | ||||
| ALPHA | Real component of Hessenberg shift scale. | Real or blank | |||||
| OMEGA | Imaginary component of Hessenberg shift scale. | Real or blank |
Remarks:
- Complex eigenvalue extraction data sets must be selected with the Case Control command CMETHOD = SID.
- METHOD = ARNO specifies that the complex Arnoldi eigensolver will be used. This is the preferred method and will handle all problems sizes. METHOD = HESS specifies that the complex general eigensolver based on the QZ method will be used. This method is only recommended when METHOD = ARNO fails and may be considerably slower for larger problem sizes. METHOD = CLAN is functionally equivalent to METHOD = ARNO.
- The extraction criteria determines the internal sorting method and controls how the ND roots requested are extracted. The following table gives the various options.
XC Setting Extraction Method Used LM Largest magnitude SM Smallest magnitude LR Largest real component SR Smallest real component LI Largest imaginary component SI Smallest imaginary component AUTO Automatic based on damping The AUTO setting selects the best option based on the type of damping specified.