gEDA-user: TwoStageAmp example

[Stuart Brorson]

>> Here's what crashes for me:
>>
>> $ ~/local/bin/gnucap spice.netlist.wpd
>> gnucap> plot ac v(Vout)
>> gnucap> ac dec 1Hz 1MegHz
>>
>> #Freq
>> Segmentation fault
>
> 1.  You need to do "op" before "ac".

I was thinking about this during my morning commute.  It's fine that
Gnucap wants an op performed before doing anything else.  However, it
shouldn't segfault if the user forgets or doesn't know this.  Rather,
Gnucap should do a check before running an analysis to verify that the
operating point has already been computed and is known.  If it's
unknown, then Gnucap should print out a warning like "No operating
point -- you probably need to run op".

> 2. The AC line is incorrect.  The "Hz" is ignored, so you asked
> for 1 step per decade, with a start frequency of 1 meg, no stop
> frequency.  It assumes the stop frequency is also 1 meg, so you
> get a single point.

Perhaps this is what caused the segfault?  Again, a little args
checking prior to running an analysis would help clean this stuff up.

Maybe I'll take this up as a project during the upcoming code sprint.

Stuart