Re: [Help-gnucap] Convergence error

[al davis]

On Friday 19 May 2006 13:31, al davis wrote:
> There is a bug in the switch model.  I have known about a
> convergence problem for a long time, but this circuit
> demonstrates it perfectly, so I found the bug quickly.  Thank
> you!

The result is still incorrect.  ng-spice gives you an incorrect 
result too.  With the patch (in the previous message), gnucap 
gives the same incorrect result as ng-spice.

To get a correct result, specify ".option method=euler".  What 
you see without this option is trapezoidal ringing, a common 
problem with simulators.

Even then, although this particular result appears to be 
correct, the algorithm is still wrong.  The patch I posted 
doesn't fix the real problem.  It just appears to make this 
particular case, sort of.   It still gets has a convergence 
problem, but appears to recover and do a good job at hiding it.

By not converging, at least gnucap let you know there is a 
problem.  I think that is better than converging to the wrong 
answer.

I'm working on it.