eigs: Compute some eigenvalues of a matrix
In dmkaplan2000/ConnMatTools: Tools for Working with Connectivity Data

Description Usage Arguments Value Author(s) See Also

This function computes a limited number of eigenvalues and eigenvectors of a matrix. It uses arpack function from the igraph package. If this package is not available, it will use the standard eigen function to do the calculation, but will issue a warning.

eigs(
  M,
  nev = min(dim(M)[1] - 1, 1),
  sym = sum(abs(M - t(M)))/sum(abs(M)) < 1e-10,
  which = "LM",
  use.arpack = TRUE,
  options.arpack = NULL
)

`M`	a matrix.
`nev`	number of eigenvalues and eigenvectors to return
`sym`	A boolean indicating if matrix is symmetric or not. Defaults to checking if this is the case or not.
`which`	A character string indicating which eigenvalues to return. Defaults to "LM", meaning largest magnitude eigenvalues. If not using `arpack`, then "SM" is also a possibility to return the smallest magnitude eigenvalues. If using `arpack`, then a number of options are possible, though they are not all guaranteed to work for all use cases. See that function for more details.
`use.arpack`	Boolean determining if calculation is to be done with `arpack` function from the igraph package. This is much quicker for large matrices, but requires igraph. Defaults to TRUE, but will use eigen instead if igraph is not found.
`options.arpack`	Additional options for `arpack`. See that function for details. Not all options are compatible with this function.