Re: [Qucs/gnucsator] Assertion failed (#9)

[al davis]

Clearly something is wrong.  Probably there is more than one problem.

If you get warnings you do not understand, you cannot trust the results.


On Fri, 17 Sep 2021 22:54:07 +0000
Dow Drake <dowdrake@msn.com> wrote:
> ;: already installed, replacing
> stashing as ;:0
> *: already installed, replacing
> stashing as *:0
> ': already installed, replacing
> stashing as ':0
> ": already installed, replacing
> stashing as ":0

; * ' " .......... are rather odd names for plugins.  I suspect a
parsing or syntax problem here.

> open circuit: internal node 5
> open circuit: internal node 3
> (+ many more warnings like this)

There is a floating subcircuit?
There is a mathematical problem that makes it impossible to solve.  The
solver may try to patch it so it can go on, because it might be just in
one iteration and will shake out in the next.  If you see a lot of
these, either results cannot be trusted or it is telling you that your
circuit burnt up.  (or both).


> Gnucap   System status
> iterations: op=0, dc=0, tran=12251, fourier=0, total=12291
> transient timesteps: accepted=39, rejected=567, total=606
> nodes: user=3, subckt=0, model=2, total=5
> dctran density=92.0%, ac density=92.0%

The circuit is simple .. only 3 user nodes, plus 2 hidden nodes inside
a model that you may not see.

The big warning here is 567 rejected steps with only 39 accepted steps.
Make a calculation ..  iterations / steps  = about 20 ... the value of
the option ITL4.  ... which says to reject a step that takes more
iterations than that to converge.

One might be tempted to increase ITL4, but it would be a waste of
time.  There is something wrong, probably in the model code, that is
giving a totally nonsense result.  It tries reducing the time step,
still doesn't work, tries again, eventually leading to that failed
assertion.

This is not something you can fix by tightening tolerances, or
loosening tolerances.