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Re: [Bug-gnucap] strange behaviour for VCR
From: |
al davis |
Subject: |
Re: [Bug-gnucap] strange behaviour for VCR |
Date: |
Tue, 15 Apr 2008 09:49:38 -0400 |
User-agent: |
KMail/1.9.9 |
On Monday 14 April 2008, address@hidden wrote:
> I was writing a frontend for ngspice-xspice above netbeans in
> java for educational purpose (I'm teacher) and I was
> interested by a more interactive simulator. So I decided to
> test gnucap. I am satisfied with it but also concerned by
> strange behaviour above xp and Linux. I'm using gnucap-0.35
Welcome .. I prefer to start students in the interactive text
mode. Most GUI's make it harder.
> I don't know if it is a bug or if I misunderstand something.
> So please, show clemency, I spend a lot of time to delimit
> this strange behaviour.
It's a bug in the limiting algorithm.
> If I try without the line "V30 30 0 1000.0", I obtain strange
> result : the voltage of the node 11 is 32.77E+12.
> If I uncomment this line, I have good result for the VCR.
> (329.34 V which is the theoretical result). This Voltage
> source would be useless !
>
> Perhaps it's a stupid error but I don't understand...
The voltage source (1000 volts) tells the simulator's limiting
algorithm that 1000 volts is reasonable. Without it, it thinks
such high voltages in a 15 volt transistor circuit are signs of
something wrong, and it tries to fix them.
For now, turn this part of limiting off:
.options vmax=1e99 vmin=-1e99
The default values of vmax and vmin are starting points. They
automatically adjust, but didn't in this case.
>
> Best regards
>
> Jacques Le Coupanec
>
>
>
>
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