Re: Potential Contributions

Kevin Cameron wrote:
> 
> According to Marq at least one simulator company has it's simulator
> handling this with sharing the current across the sources, I'll presume
> that they had some motivation for doing so.

Since one simulator actually allowed unequal voltage sources to
be placed in parallel, it is almost certain that this simulator
indeed did place GMIN-like resistors in series with the voltage
sources.

I would guess the motivation was along the lines:
Customer: hey, why can't I do this?  The voltages are equal!
  What a dumb simulator.
AE: OK, I'll ask R&D to fix it.

and R&D might not have ever seen the test case, which might
have had exactly the sorts of problems Ken mentions.


> We need a definition of the behavior of parallel potentials for the LRM,
> my view is that they should be allowed as long as the potential is
> exactly the same and the current will be split evenly across the
> potentials (and the user gets a warning). If you disagree propose
> something different.

As Marq pointed out, the potential is quite likely to be
not exactly equal: 1/1/3 versus 3.  I've also seen cases where
(on Intel machines) one floating-point number is stored in 
an 80-bit register in the CPU and compared to a 64-bit number
in the cache, and they don't match in those extra bits.

-Geoffrey

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