Eigen Command: Difference between revisions

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|  style="width:150px" | '''$numEigenvalues''' || number of eigenvalues required
|  style="width:150px" | '''$numEigenvalues''' || number of eigenvalues required
|-
|-
| '''$solver'''|| optional string detailing type of solver: -genBandArpack, -symmBandLapack, -fullGenLapack (default: -genBandArpack)
| '''$solver'''|| optional string detailing type of solver: -genBandArpack, -fullGenLapack (default: -genBandArpack)
|}
|}


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# The eigenvectors are stored at the nodes and can be printed out using a Node Recorder, the nodeEigenvector command,  or the Print command.
# The eigenvectors are stored at the nodes and can be printed out using a Node Recorder, the nodeEigenvector command,  or the Print command.
# The default eigensolver is able to solve only for N-1 eigenvalues, where N is the number of inertial DOFs. When running into this limitation the -fullGenLapack solver can be used instead of the default Arpack solver.
# The default eigensolver is able to solve only for N-1 eigenvalues, where N is the number of inertial DOFs. When running into this limitation the -fullGenLapack solver can be used instead of the default Arpack solver.
# The -fullGenLapack option is VERY SLOW for moderate to large models





Latest revision as of 19:38, 19 August 2022




This command is used to perform the analysis.

eigen <$solver> $numEigenvalues

$numEigenvalues number of eigenvalues required
$solver optional string detailing type of solver: -genBandArpack, -fullGenLapack (default: -genBandArpack)


RETURNS:

a tcl string containg eigenvalues.


NOTES:

  1. The eigenvectors are stored at the nodes and can be printed out using a Node Recorder, the nodeEigenvector command, or the Print command.
  2. The default eigensolver is able to solve only for N-1 eigenvalues, where N is the number of inertial DOFs. When running into this limitation the -fullGenLapack solver can be used instead of the default Arpack solver.
  3. The -fullGenLapack option is VERY SLOW for moderate to large models


THEORY:


<math> \left (K - \lambda M \right ) \Phi = 0 </math>



EXAMPLE:

set eigenvalues [eigen 10];



Code Developed by: fmk