Re: [SI-LIST] : **error**: internal timestep too small

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From: Kim Helliwell (khelliwe@acuson.com)
Date: Thu Jan 20 2000 - 13:03:26 PST


"Muranyi, Arpad" wrote:
>
> Kim,
>
> I meant the series version:
>
> U-element---------R-------|---------R---------U-element
> |
> U-element---------R-------node---------R---------U-element
> |
> U-element---------R-------|---------R---------U-element
>
> I used resistors much less than 1 Ohm, something like 1e-4 or so.
> I also reported this to Avant! and since it was around the time
> when the W-element came out I was told that I should not expect
> any research and fixes to this.
>
> Arpad Muranyi
> Intel Corporation
> ====================================================================

OK, I thought that probably was what you meant. The other
possibility I mentioned wouldn't really make sense to me.

I wonder if this is similar to putting a series parasitic
resistor on a diode that is otherwise ideal. The resistor
limits the otherwise runaway current in forward bias therefore
helps convergence.

That much less than 1 ohm is a bit dangerous, in general. You
can lose needed accuracy by using very small resistors.

So, apparently Avant! is abandoning the U model entirely? I
find that to be a flawed attitude.

-- 
Kim Helliwell
Senior CAE Engineer
Acuson Corporation
Phone: 650 694 5030  FAX: 650 943 7260

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