# Get Eigenvalue

Allows the extraction of a single eigenvalue from the spectrum of an operator.

## Inputs

• $\{ E_n \}$: list of real numbers - the eigenvalues to extract a single value from

## Outputs

• E: A real number - the eigenvalue extracted from the list

## Content

In the text field, the index of the desired eigenvalue has to be input. Note that indexing starts with zero.

## Error messages

in addition to input errors, the node shows an error when the desired eigenvalue is not in the list of eigenvalues of the spectrum