al davis wrote: > Another interesting type of analysis that Spice doesn't have is > a semi-symbolic analysis, where the result is a transfer > function, in S, that has some values carried through as > symbols. I would have to help you a lot, but it would be a > real accomplishment, and I think I know of a few places where > you could get a paper out of it. .. at least a conference > paper, maybe two, maybe even a journal paper.
anyone remember the program xfunc which did exactly this? I have tried to track down the author a few times over the years with no luck. The manual says: XFUNC 1.2 Transfer Function Symbolic Calculator Copyright 1991 - YY Corporation The program was distributed with sources and a DOS binary. The programmer is listed as Henry Yiu. History shows 1989 as the original release date and 1991 as the most recent. I do not see any sort of license anywhere. Just the copyright notice. The tool worked and really my primary complaint was that you quickly ended up with an expression that a) was not at all a low entropy expression (see various papers by Middlebrook or the textbook by Vorperian) b) represented polynomials as the coefficients like 1 + a1*s + a2*s^2 + a3*s^3 .... which of course tends to be a poor way to represent polynomials from both a numerical sense and an insight sense. That said, it was still useful from time to time. If anyone would have a clue on how to contact Henry Yiu it might be interesting to see if he would provide a license that allows for redistribution. GPL would work. The program is in C and doesn't take much to build on modern systems. If he were willing, I'd volunteer to get it into a version control system (probably git) and provide a build system other than the DOS build system. -Dan -Dan _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user