PSS == Pseudo Steady-State algorithm (e.g. http://www.mos-ak.org/sanfrancisco_2012/presentations/T05_Lannutti_MOS-AK_121212.pdf).?
A PSS is useful for power electronics circuitry (where the steady-state is a trajectory in state-space).
When the option UIC is *not* used,?SPICE?automatically finds an initial solution?at t=0. This?works (very) well for most analog (non-switching) circuits.?With UIC one can provide a hint for the steady-state. IMHO this should be faster in all non-trivial cases, but I notice that the experience of people in this forum is different.
A?brute-force PSS algorithm?simply runs a .tran until you detect that the state trajectories are converging. This convergence is actually?quite?tricky to detect, especially when there is feedback involved.
I hope this answers your question.
-marcel
