Eigenvalue algorithm does not handle complex case correctly

[jbrown1618]

https://github.com/jbrown1618/vector/blob/6af9d0da34900c2cd746334e3029026261153b85/src/algorithms/Eigenvalues.ts#L70

https://scicomp.stackexchange.com/questions/30407/how-does-the-qr-algorithm-applied-to-a-real-matrix-returns-complex-eigenvalues