# Eigen Command
This command is used to perform the analysis.
```tcl
eigen <$solver> $numEigenvalues
```
numEigenvalues
|
number of eigenvalues required |
solver
|
optional string detailing type of solver: -genBandArpack,
-symmBandLapack, -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.
## Theory
-
$$\left (K - \lambda M \right ) \Phi = 0 $$
## Examples
set eigenvalues [eigen 10];
Code Developed by: fmk