EIGC

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
MAX Normalize to unit value of the largest magnitude to a unit value for the real part and a zero value for the imaginary part.
POINT Normalize the component defined in fields 5 and 6 to a unit value for the real part and a zero for the imaginary part.
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:

  1. Complex eigenvalue extraction data sets must be selected with the Case Control command CMETHOD = SID.
  2. 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.
  3. 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.