EIGC

Bulk Data Entry Defines data required to perform complex eigenvalue analysis.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
EIGC SID NORM G C ND0
Continuation for EIGC
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
ALPHAAJ OMEGAAJ ND1
EXTN UB

Example 1

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
EIGC 4 MAX 15

Example 2

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
EIGC 4 MAX
15

Example 3

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
EIGC 4 MAX
1000.0 1000.0 15

Definitions

Field Contents SI Unit Example
SID Unique set identification number.

No default (Integer > 0)
NORM Indicates the option for normalizing eigenvectors.
MAX (Default)
Normalize the component having 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 value for the imaginary part. The value for NORM defaults to MAX if the magnitude of the defined component is zero.
G Grid or scalar point identification number. Required only if NORM = POINT.

No default (Integer > 0)
C Component number. Required only if NORM = POINT and G is a geometric grid point.

No default (0 ≤ Integer ≤ 6)
ND0 Desired number of roots and eigenvectors to be extracted.

Required if there is no continuation, and it must be empty if the ALPHAAJ continuation line exists.

Default = blank (Integer > 0)
ND1 Desired number of roots and eigenvectors to be extracted.

No default (Integer > 0)
ALPHAAJ Real part of the shift point.

Default = 0.0 (Real)
OMEGAAJ Imaginary part of the shift point.

Default = 0.0 (Real)
EXTN Flag indicating that parameters for EIGC entry are to follow.
UB Upper bound of the frequency up to which Complex Eigenvalue pairs will be output. This option only affects the output and not the analysis. 3

Default = blank (Real)

Comments

  1. ALPHAAJ and OMEGAAJ are only useful for direct complex eigenvalue analysis. If there is no METHOD command present in the subcase control area, the direct method is considered for the complex eigenvalue analysis. Otherwise, modal method is used.
  2. The third field is reserved for a numerical complex eigensolution (METHOD). Currently, this field should be left blank; however, certain method types (INV, HESS and CLAN) will be accepted, but there will be no effect on the analysis.
  3. For modal complex eigenvalue analysis, set the ND0 field to AUTO.