UIC option in SPICE?

I have read all I could find about the Use Initial Conditions (UIC) option in SPICE, but I still don't fully understand it. The reason I am confused is this: When I run a DC transient analysis with UIC enabled on a simple RLC tank circuit (with all passives having an IC of '0'), shouldn't these results be the same as a DC transient simulation with *no* UIC, since they should both have a initial starting condition of 0V/0A? Yet with the simulation with no UIC enabled, the circuit reaches steady state instantly; while with the UIC option enabled it takes a finite time to reach its voltage level, then over/undershoots a few time (rings) -- as it should. What am I missing here?

Thank You,

-Bill

If UIC is not specified then SPICE does not assume zero initial conditions. By default SPICE will solve for the DC operating point of the circuit before performing a transient analysis, and use that for the initial conditions.

The originating message was also posted to sci.electronics.cad but was not cross-posted, so I have cross-posted now.

Jonathan

Thanks very much for the clear answer Jonathan! Very much appreciated.

Best Regards,

-Bill