Re: gEDA-user: Mathematical expressions in gnucap?

[John Doty <jpd@xxxxxxxxxxxxx>]

On Sep 18, 2007, at 5:48 PM, al davis wrote:

> On Tuesday 18 September 2007, John Doty wrote:
>> If you have Mathematica
>
> Have you tried "Mathomatic"?

No. So many packages, so little time ;-)

>
> It's a free (GPL) symbolic math program.  I don't know how it
> compares to Mathematica, which is a commercial product.

I like "free" for its advantages, when they apply, not out of  
ideology. But I've been using Mathematica for almost two decades and  
have an extensive collection of "notebooks" covering my many  
interests: that's a very valuable resource, difficult to give up. I  
find benefit/cost for Mathematica very high. But show me an  
interesting *community*, and I might get interested in their tool.

I note that if somebody is an expert on another package, it should be  
easy to change my gnetlist back end to support it. It basically  
generates:

A series of assignments equating pin voltages with the corresponding  
net voltages.

A list of equations representing Kirchoff's current law for each net.

A list of model invocations, one for each device. Mathematica expands  
these into more equations.

A list of pin currents and net voltages. This tells Mathematica which  
symbols are variables (the rest are assumed to be parameters).

To adapt this to a different computer algebra system, I think only  
minor changes in the output (to adapt to the syntax of the system)  
would be required. The support definitions in gEDAmath.m would also  
require translation, but they're not complicated.

John Doty              Noqsi Aerospace, Ltd.
http://www.noqsi.com/
jpd@xxxxxxxxx




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