Continuous system simulation packages?

[GFA001K%CALSTATE.BITNET at ricevm1.rice.edu]

Anyone know of a good continuous system simulation package that runs on a
SSI?  How about a object/graphical model building front-end for some of
the traditional type simulation packages like simusolve?

Thanks!

Brad Finney
Environmental Engineering Department, Humboldt State University
Arcata, CA  95521
gfa001k at calstate.bitnet