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.