RE: [ng-spice-devel] Re: snapshot/resimulate


To <ng-spice-devel@ieee.ing.uniroma1.it>
From "Jon Engelbert" <jon@beigebag.com>
Date Thu, 12 Apr 2001 13:06:17 -0400
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Al,
I think that the source of our disagreement is that I've been assuming that
the graphics program is a separate executable.  You are right as long as the
graphics program that you are analyzing data with is the same as the program
that is running the simulation.

Regarding your licensing concerns, this could be a Windows only option, and
it would not have any licensing ramifications on Windows because Microsoft
allows free distribution of the database libraries.

The advantages of using the database only show up when the graphics program
is separate.  I'm not a big fan of the graphing that comes with
spice/nutmeg.  I like to use a graphics program that is a user-friendly: It
"should" allow you to add and remove plots, to zoom-in and scroll, to find
maximum & minimum, to see values as you move the cursor across a plot, etc.

So, let me narrow down the scope of my plug for the database;
If it's a large circuit, the simulation generates a lot of data points, and
the user wants to be able to pick and choose what he wants to probe after
the simulation is complete, then the database approach has advantages.  It's
not a core issue, so I'm willing to shut my mouth on this topic now.

Jon Engelbert
President, Beige Bag Software
279 E. Liberty, Ann Arbor, MI 48105
jon@beigebag.com

-----Original Message-----
From: Al Davis [mailto:aldavis@ieee.org]
Sent: Thursday, April 12, 2001 2:21 AM
To: ng-spice-devel@ieee.ing.uniroma1.it
Subject: Re: [ng-spice-devel] Re: snapshot/resimulate

On Wed, 04 Apr 2001, Jon Engelbert wrote:
> On Microsoft Windows, the Data Access Objects (DAO) libraries make
> it possible to store simulation data into a database.  DAO is
> "free" with Windows.  This way, all of the data that is generated
> by the simulator can be stored to the hard drive and, if the
> database is set up logically, then the data can be retrieved into
> RAM as needed.  I think that this is the ideal solution to the
> problem.

There are two immediately apparent problems with this approach:

First, any libraries used must have acceptable licensing and
availability.  For ACS, this means anything required must have a
GPL-compatible license, implying that source is available and can be
redistributed.

Even if it is GPL, I would not use someone elses code for something
that is absolutely necessary.  In this case, for a non-GPL license, I
could leave out that part.


Second, performance is a big issue.  It may be good, even optimal, as
a random access database, written one record at a time, but that
doesn't make it optimal for this application.  A raw dump of an array
is about as fast as you can get, and the standard C library will do
that.


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