Re: [ng-spice-devel] New data file format
On Thu, 7 Dec 2000, Steve Hamm wrote:
> ---"AG" == Gillespie, Alan <Alan.Gillespie@analog.com> writes:
>
> AG> I think the standard binary format outputs double precision
> AG> data, which is overkill in my opinion, although I know some
> AG> people disagree. But single precision halves the file size,
> AG> and therefore doubles the access speed. Single precision has
> AG> plenty resolution, way more than any reasonable reltol
> AG> setting. At least, the precision could be optional.
>
> Generally, any situation where the dynamic range exceeds 140db would
> need double precision. I can think of a few examples, off the top of
> my head: Looking at settling time of a precision amplifier, microvolts
> on a 1v signal may be significant. To accurately resolve those
> microvolts, 1e-7 or 1e-8 reltol would be useful. Or, transient
> analysis followed by an FFT, where you want the noise floor more than
> 140db down, would also fit. Also, AC simulation of very high-Q
> circuits may also need results of more than 7 digits.
I generally agree that I hate to lose the option for extreme accuracy.
What I'd be in support of though is an option. So the default would be
single precision unless you set some option in the simulation. And of
course the binary file would have a flag to indicate single/double
precision. That way you get the size/speed benefit for the most common
cases, but can get more if you want/need it.
-Dan
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