gEDA-user: Re: specifying an arbitrary function as ac source

["H.S." <hs.samix@xxxxxxxxx>]

Stuart Brorson wrote:
>>How do I specify an aribtrary ac source in gschem? For example,
>>I want a current a source of e^(At)sin(Bt) where A and B are some constants.
>>
>>I have tried searching google, but am not sure what I should
>>specifically search for. I have found that I can specify an ac source
>>with an amplitude and a phase, but not how to specify a source which an
>>arbitrary function of time.
> 
> 
> Ummmm, what kind of arbitrary AC source are you looking for?  I assume
> SPICE.   If so, SPICE doesn't support arbitrary source
> waveforms using a single device.  It gives you things like sine, PWL,
> DC, and a few others which I have forgotten.  Here's the SPICE
> documentation on sources: 
> 
> http://newton.ex.ac.uk/teaching/CDHW/Electronics2/userguide/sec3.html#3.2
> 


Thanks for the pointer. I see that we can form exp and sin sources. It
took me quite some time to decipher the syntac in which the specs for
exp are written. Actually, a differently phrased explanation in a text
book's appendix showed me the light. I also see that the sin source is
itself an exponentially decaying source! So I do not need two different
sources at all to get an exponentially decaing sinusoidal. The only that
remains is how do I insert a phase change. Or, special case, how do I
get a cosine source.

thanks,
->HS