Complex Eigenvalue dialog box (Nastran)

Modeling Object
Name	A descriptive name for this modeling object.
Label	Specifies a unique numerical identifier for this modeling object.
Description	Lets you specify a description for this modeling object.
Complex Solution Options – All Methods
Complex Eigenvalue Extraction Method	METHOD field in the EIGC bulk entry.Lets you specify the method of complex eigenvalue extraction.Select Hessenberg to use the Hessenberg method, which is generally more reliable and economical for small and moderate-sized problems. The Hessenberg method computes all eigenvalues and ND eigenvectors. Select Inverse Power to use the Inverse Power method. Select Complex Lanczos to use the Complex Lanczos method. Note: For a SOL 402 complex modes analysis, you must select Complex Lanczos. SOL 402 does not support the other extraction methods. Single vector complex Lanczos is used for SOL 402.Select Iterative-Schur-Rayleigh-Ritz to use the ISRR method. ISRR is a complex eigenvalue extraction method which works well on sparse matrices, confines the search region to a circle centered on the origin of the complex plane, and provides some reliability that all modes within the circle have been found. See Complex Eigenvalue Analysis in the Simcenter Nastran Numerical Methods Guide for more information.See Complex Eigenvalue Methods in the Simcenter Nastran Advanced Dynamics User's Guide for more information.
Number of Desired Modes	ND0 field in the EIGC bulk entry. Lets you specify the number of modes to calculate.
Convergence Criterion

Inverse Power method options

Search Region End A (Real)	ALPHAAj field in the EIGC bulk entry. Specifies the real part of Aj. Lets you define the end point Aj of the j-th search region in the complex plane.
Search Region End A (Imaginary)	OMEGAAj field in the EIGC bulk entry. Specifies the imaginary part of Aj.
Search Region End B (Real)	ALPHABj field in the EIGC bulk entry. Specifies the real part of Bj. Lets you define the end point Bj of the j-th search region in the complex plane.
Search Region End B (Imaginary)	OMEGABj field in the EIGC bulk entry. Specifies the imaginary part of Bj.
Search Region Width	Lj field in the EIGC bulk entry. Defines the width of the search region

Complex Lanczos method options

Shift Point (Real)	SHIFTRj field in the alternate EIGC bulk entry. Specifies the real part of shift j. Enter a real number.
Shift Point (Imaginary)	SHIFTIj field in the alternate EIGC bulk entry. Specifies the imaginary part of shift j. Enter a real number.
Maximum Block Size	MBLKSZj field in the alternate EIGC bulk entry. Specifies the maximum block size at shift j. Enter an integer > 0.
Initial Block Size	IBLKSZj field in the alternate EIGC bulk entry. Specifies the initial block size at shift j. Enter an integer > 0.
Frequency of Solve

Iterative-Schur-Rayleigh-Ritz method options

Shift Point (Real)	SHIFTRj field in the alternate EIGC bulk entry. Specifies the real part of shift j. Enter a real number.
Shift Point (Imaginary)	SHIFTIj field in the alternate EIGC bulk entry. Specifies the imaginary part of shift j. Enter a real number.
Force Out-of-Core Path	ISRRFLG field, option 2 in the alternate EIGC bulk entry. Select this option to force the out-of-core path in the code.
Override System Cell 405	ISRRFLG field, option 4 in the alternate EIGC bulk entry. Select this option to override system cell 405.
Force Balanced Iteration	ISRRFLG field, option 8 in the alternate EIGC bulk entry. Select this option to force balanced iteration for real unsymmetrical problems only.
Force Starting Vectors Generation	ISRRFLG field, option 16 in the alternate EIGC bulk entry. Select this option to force the generation of starting vectors for quadratic problems from the values found for the linear case when damping is ignored. In all other cases, the software randomly generates the starting vectors.
Maximum Size of Iteration Subspace	ISRRFLG field, option M*32 in the alternate EIGC bulk entry. Forces the maximum size of the subspace to the number of vectors you specify.

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Defining eigenvalue extraction data for Nastran analyses

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Complex Eigenvalue dialog box (Nastran), Simcenter 3D 2021.1 Series

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