[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
## Re: [Help-gnucap] Convergence error

**From**: |
al davis |

**Subject**: |
Re: [Help-gnucap] Convergence error |

**Date**: |
Fri, 19 May 2006 19:19:24 -0400 |

**User-agent**: |
KMail/1.9.1 |

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.