Eigen Command: Difference between revisions

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:

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 -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

@@ Line 25: / Line 25: @@
 # 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.
-# Note: the fullGenLapack is VERY SLOW for moderate to large models
+# The -fullGenLapack option is VERY SLOW for moderate to large models