2009/10/29, Alan Grimes <agrimes@...>:
> In recent weeks, all of my changes had to do with the Component
> heirarchy, fixing pins and wires, and a pass through the connector
> I've also added some compile-time switches to toggle strict error
> checking in the engine, that's all.
> Okay, so what in god's name is going on here? Well, I'll tell you.
> Problem 1:
> The row permutation algorithm is broken.
> Many cases the engine will be given a pathalogical but non-broken
> matrix. A matrix for which there is a solution but the current
> single-pass permutation system will not find the correct permutation and
> then the thing goes crazy. When this happens, the simulation goes crazy
> showing absurdly large currents and voltages. Want to know why? The
> permutation loop. Fixing it will not be easy and will involve carefully
> evaluating how changes to that loop will affect the partial solution
> cache that ktechlab owes much of its speed to.
> There are a number of things that can be done to further improve the
> performance of the linear algebra engine but these will not earn you
> more than 5% over what we have now. The slowness we see in profiling is
> due to the issues below. (It might also simply be inherent to the
> problem at hand...)
> Problem 2: Nonlinear and all of its children.
> The reason perform non-linear is slow is two reasons, first, inherent
> slowness in the system and second, because the models for a number of
> the components are horribly, horribly wrong. I'm about 85% sure that the
> computation of the conductance of the diode in forward bias is correct.
> I'm not at all sure about the current calculation. =( Also, correcting
> the conductance in the diode seems to have broken something about Jfet,
> which had seemed to be doing very well recently. =( (Not all of these
> changes are in SVN).
> To better understand WTF is going on here, the word of the day may as
> well be "Numerical Integration." What is basically going on is that the
> nonlinear classes generate values for the derivative of the conductance
> and then by iteration attempt to converge on the solution. If this
> works, everything's happy. If it doesn't, well...
> Problem 3: My current diodeTest circuit is showing some faults that I
> can't readily explain. The test of the many different LED circuits seems
> to stall out even though the engine is configured to keep going no
> matter what. I have no idea what's really going on there. =(
> New president: Here we go again...
> Chemistry.com: A total rip-off.
> Powers are not rights.
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Enviado desde mi dispositivo móvil
Naranjo, Manuel Francisco
Wireless Cables Inc.