This set of matrices if from the application of the Hydro-Quebec power systems' small-signal model. In the application, one wants to compute all eigenvalues a + b i in a box of the complex plane. Specifically, a_{min} < a < a_{max} and, in general, a_{min} = -300 and a_{max} = 300. b_{min} < b < b_{max}, and, in general, b_{min} = 0 and b_{max} = . Note that the matrices are highly unbalanced.

Matrices in this set:

QH1484 (real unsymmetric, 1484 by 1484, 6110 entries)

QH768 (real unsymmetric, 768 by 768, 2934 entries)

QH882 (real unsymmetric, 882 by 882, 3354 entries)