Re: VAMS for CM: $limit and $previous


Subject: Re: VAMS for CM: $limit and $previous
From: Geoffrey.Coram (Geoffrey.Coram@analog.com)
Date: Tue Jan 20 2004 - 09:10:14 PST


Sri -
I believe the correct value to return on the first iteration of a
timestep is indeed the accepted value from the previous timestep,
and you must be able to "rewind" if a timestep gets rejected.
This makes it expensive in terms of memory, because the simulator
has to keep the "state" between iterations as well as for each
timestep. For this reason, limiting is usually restricted to
branch voltages, which can be easily recomputed by the simulator
(because it has to save the V-vector anyway).

-Geoffrey

Chandrasekaran Srikanth-A12788 wrote:
>
> Just something on the tangent from the discussion with regards to the behaviour of $previous. Just want to clarify the meaning of this syntax which returns value from the previous iteration.
>
> What value is returned on the first iteration of the timestep? Does it return the accepted value of the previous timestep? Also what happens after doing multiple iterations if the timestep gets rejected? Does the first iteration of the new timestep go for the last "accepted" value. Hope this is not confusing.
>
> cheers,
> Sri



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