Eigen Command: Difference between revisions

Revision as of 00:44, 1 June 2013

This command is used to perform the analysis.

eigen <$type> <$solver> $numEigenvalues

$numEigenvalues	number of eigenvalues required
$type	optional string detailing type of eigen analysis: -standard or -generalized (default: -generalized)
$solver	optional string detailing type of solver: -genBandArpack, -fullGenLapack, -UmfPack, -SuperLU (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.

THEORY:

Standard Problem:

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

Generalized Problem:

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

EXAMPLE:

set eigenvalues [eigen 10];

Code Developed by: fmk

@@ Line 4: / Line 4: @@
 {|
-| style="background:yellow; color:black; width:800px" | '''eigen <$type> <$solver> $numEigenvalues'''
+| style="background:light green; color:black; width:800px" | '''eigen <$type> <$solver> $numEigenvalues'''
 |}
@@ Line 14: / Line 14: @@
 |  '''$type''' || optional string detailing type of eigen analysis: -standard or -generalized (default: -generalized)
 |-
-| '''$solver'''|| optional string detailing type of solver: -genBandArpack, -symmSparseArpack, -symmBandLapack, -fullGenLapack, -UmfPack, -SuperLU (default: -genBandArpack)
+| '''$solver'''|| optional string detailing type of solver: -genBandArpack,  -fullGenLapack, -UmfPack, -SuperLU (default: -genBandArpack)
 |}