Re: gEDA-user: File instead of SPICE voltage source?

[al davis <ad82@xxxxxxxxxxxxxxxx>]

On Tuesday 03 May 2005 02:52 am, Shahab Sanjari wrote:
> The file exists before. a large one. near 30,000 samples each
> 1ms apart, produced by a data acquisition system.
> like this:
>
>    0.0000    14.65
>    0.0010   -10.99
>    0.0020   -26.86
>    .
>    .
>    .
>    29.9920   -73.24
>    29.9930   -105.0
>    29.9940   -78.13
>
> The original file was comma separated, I removed them with a
> SED script.

It shouldn't matter.  gnucap's parser is pretty forgiving.  
Commas are optional.

As I recall, Spice treats commas like white space.

Actually, it is too forgiving.  When I first started using that 
parser, it was way too forgiving.  You could sometimes feed it 
a line of garbage, and it would find the nearest correct parse, 
with surprises.

You do need to make it look like one line, either by ending each 
physical line with "\" (C style) or beginning each extension 
with "+" (Spice style).

> my experiment with PWL and spice ( my last email ) was
> successful, but it was slow.

Why was it slow?  Big circuit?  Lots of points?

Sometimes it is a good idea to filter the data, and generate a 
reduced set of points.

> I am new to splines, but the idea is interesting, since it
> shows the behavior of the original analog signal better than
> a PWL.
>
> How is this possible with GNU-CAP?
>
> in the case of a quadratic or cubic spline, what value should
> I choose for transient analysis step size?

If you have enough points, splines probably won't help.  The 
benefit is that it lets you use fewer points.

Whatever you need to see the signal without aliasing.  Try it 
and see.