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 1: / Line 1: @@
 {{CommandManualMenu}}
+This command is used to perform the analysis.
+{|
+| style="background:lightgreen; color:black; width:800px" | '''eigen  <$solver> $numEigenvalues'''
+|}
+----
+{|
+|  style="width:150px" | '''$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: <span style="color:blue"> fmk </span>