At 11:06 PM 11/7/00 -0500, you wrote: Ever since the late 60's, very large simulations of power grids were being performed on analog computers for the purposes of contingency analysis and dynamic stability assessment. These special-purpose analog computers filled entired rooms and sometimes had thousands of dynamic states (one integrator per dynamic state). Back in 1992, I remember that I was running a simulation of a large power system on a Sparcstation IPX with 32MB or RAM. The model had several thousand states, and, with all of the storage overhead, the machine was swapping frantically for a couple of days while the simulation ran. An older faculty member saw that, and told me that he was solving problems of that size in one morning in the 60's. Most of the work involved setting the initial conditions and making sure that several dozen plotters had enough paper to print all of the results :-) . The actual simulation ran in just a few minutes. Carlos.