eigenvalues 0.4.0

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Eigenvalue Decomposition
========================
This package contains some iterative algorithms for computing the eigenvalues/eigenvectors of a symmetric matrix **H**, implemented in [Rust](https://www.rust-lang.org/).

## Matrix Representation
The library examples represent **H** using the [nalgebra](https://nalgebra.org/) *DMatrix* type, but the matrix **H** does not need to be dense. Sparse or other representations are handled by implementing the `Matrixoperations` trait.

## Available Algorithms:
 * **Davidson** using either  Diagonal-Preconditioned-Residue (**DPR**) or Generalized Jacobi Davidson (**GJD**). See [Davidson Diagonalization Method](https://www.semanticscholar.org/paper/DAVIDSON-DIAGONALIZATION-METHOD-AND-ITS-APPLICATION-Liao/5811eaf768d1a006f505dfe24f329874a679ba59)
 * **Lanczos**, see [Hermitian Lanczos](https://en.wikipedia.org/wiki/Lanczos_algorithm)


### Note:
The Davidson method is suitable for **diagonal-dominant symmetric matrices** that are quite common
in certain scientific problems like [electronic structure calculations](https://en.wikipedia.org/wiki/Electronic_structure). The Davidson method could be not practical
for other kind of symmetric matrices.