Roll the credits

If you are interested in the people behind Symbulator, here's who made it and who helped, plus some acknowledgements. And some glowing reviews received over the decades.

Last updated 2026-09-06

Who made Symbulator

Symbulator and its documentation, in all its versions up to this date, have been made by me, Roberto Perez-Franco. I started coding it as an engineering student at the Technological University of Panama (Universidad Tecnológica de Panamá) in Azuero, and the timeline below has the dates.

A timeline

Date	Event
30 March 1999	The first line of code, at the Technological University of Panama in Azuero.
2 April 1999	Version 0.92, the first public release, goes onto the Internet.
29 May 1999	Version 0.994 — the equivalent of version 1.
19 August 1999	Version 2, presented in person for the first time, at UTP Azuero.
October 1999	The Elect SCS plug-in. The program is still called SCS.
November 1999	The paper is written.
Late 1999 or early 2000	Version 3.
14 May 2000	The Power Tools plug-in. The program is now called Symbulator.
October 2000	First place, IEEE Region 9 Student Paper Competition.
December 2000	The paper is published in Panama, in the bulletin of the IEEE section.
9 January 2001	Version 4.
30 March 2001	Version 5, called Q.
9 July 2001	The thesis is defended, and graded 100 out of 100.
September 2001	The paper is published in Barcelona, in the magazine of the IEEE student branch.
June 2013	Version 6, written at MIT.
July 2023	Versions 7 and 8, written in Melbourne.
13 August 2026	The symbulator package goes onto PyPI.
28 August 2026	Version 9, a public beta.
1 October 2026	Versions 9 and 8 leave beta.

What Symbulator did for me

I've never made any money from Symbulator: it has always been and will remain free of charge. But I have benefited from Symbulator in other ways. Thanks in large part to Symbulator, I landed my first job, received a Distinguished Alum award from UTP in 2008 and an Outstanding Young Person (TYOP) award from the Panamanian chapter of Junior Chamber International (JCI), and won a Fulbright Scholarship that took me to a Master of Engineering and later a PhD in Engineering Systems at the Massachusetts Institute of Technology. MIT then hired me, and I lived in Boston for almost twelve years. I now live in Melbourne, Australia. You can say that writing Symbulator changed my life. Beyond my lifetime, Symbulator may preserve a part of my mind as it solves circuits for new generations, the same way a composer lives in the tunes or a writer in the words they conceived.

Dedication

Two people made Symbulator possible, with their love and support.

The first is my wife Monica, who had the patience to live with a cyborg for all the years my mind was focused on coding and documenting. Mi reina, my attention was elsewhere, but my heart was always with you.

The second is my late father Tito, who invested time and money in my education and bought me every gadget and every book I needed or wanted for my studies, with a blind faith that one day something good would come of it. I'm happy to know that I made you proud, Dad, and I miss you every day.

How to reach me

If you liked Symbulator, let me know. My email is my given name, then my last name with a hyphen, as a dot-com address, like so: rxxxxxx@pxxxx-fxxxxx.cxx

Acknowledgements

Human collaborators

Over the past decades, many people have made Symbulator better through their suggestions and corrections, on both the software and the documentation. Many were complete strangers at first and became dear friends through our exchanges. Others were dear friends that became collaborators.

Versions 1 through 6 received feedback and suggestions from José Vega (Panama), Tim Hutcheson (USA), Lars Frederiksen (Denmark), Joe Riel (USA), Arne Harstad (Norway), Erwin Baert (Belgium), Charles 'Chuck' Ware (USA), Doug Burkett (USA), Reinhard Willinski (Germany), Kamil Malinski (Austria), Jake Adams (USA), Daniele Martini (Italy), Rozgonyi Szabolcs (Hungary), Michael Rans (UK), Alex Astashyn (Russia), Al Charpentier (USA), Nevin McChesney (USA), Ivan Oro Yu (Panama), Pepe Iborra (Spain), and Dave Conklin (USA). Versions 7 and 8 received feedback and suggestions from Carlos Perez Ortega (Chile) and Qifan Wang (China).

Version 9 benefited from feedback and excellent suggestions from my dear old friend Antony García (Panama), who is not only one hell of an engineer and a consummate circuit theorist, but who also taught the same Circuits class at UTP as Prof. Eliane Boulet for many years. I met Antony in May 2013, while he was a student at UTP Azuero in the same major that I had completed more than a dozen years earlier. I was immediately struck by his brilliance, and we became friends. In August 2026, I shared an early version of Symbulator 9 with Antony while he was a PhD candidate in the ECE Department at WPI (MA, USA). Antony generously provided me with a series of fantastic recommendations — from his vantage point as both a student and a teacher of circuit theory — regarding features he would like to see in Symbulator. I worked with Claude over a few weeks in September to turn them into reality.

My thanks to all of them. I truly am in their debt.

Software I relied on

Symbulator 8 relies on Lars Frederiksen's Laplace functions, adapted for the TI-Nspire by Philippe Fortin. I have renamed that file LF here, in homage to Lars.

Problem credits

To make this book useful to actual students, the problems were chosen from widely used textbooks on electric circuit analysis, and their circuit diagrams are reproduced here as they appear in the source.

Code	Textbook
AS2	Fundamentals of Electric Circuits (2nd ed.), Charles K. Alexander and Matthew N. O. Sadiku, McGraw-Hill, 2004
AS5	Fundamentals of Electric Circuits (5th ed.), Alexander and Sadiku, McGraw-Hill, 2013
AS7	Fundamentals of Electric Circuits (7th international ed.), Alexander and Sadiku, McGraw-Hill, 2020
B11	Introductory Circuit Analysis (11th ed.), Robert L. Boylestad, Pearson – Prentice Hall, 2007
Bo2	Elementary Linear Circuit Analysis (2nd ed.), Leonard S. Bobrow, Oxford, 1987
HK5	Engineering Circuit Analysis (5th ed.), William H. Hayt Jr. and Jack E. Kemmerly, McGraw-Hill, 1993
NR9	Electric Circuits (9th ed.), James W. Nilsson and Susan A. Riedel, Prentice Hall, 2011
NR11	Electric Circuits (11th ed.), Nilsson and Riedel, Pearson, 2020
NR12	Electric Circuits (12th ed.), Nilsson and Riedel, Pearson, 2023
RM3	Circuit Analysis: Theory and Practice (3rd ed.), Allan H. Robbins and Wilhelm C. Miller, Thomson – Delmar Learning, 2004
TR5	The Analysis and Design of Linear Circuits (5th ed.), Roland E. Thomas and Albert J. Rosa, Wiley, 2006

For the purpose of teaching students how to use Symbulator, these diagrams are reproduced under the principle of fair use. No copyright infringement is intended.

Praise received

Over the past quarter of a century, the words of encouragement I received from users of Symbulator were my incentive to keep working on it. Here is a little of that precious collection.

The masterpiece of TI-89 programming.
— Alex Astashyn, EE+CoE+CoS major, Polytechnic University, Brooklyn, New York, USA

Symbulator is and always will be the best program for TI-89/92/V200.
— Charles Ware, EE major, Columbus, Ohio, USA

Roberto, your program Symbulator is by itself a reason to buy the calc. It's a masterpiece of programming.
— Pepe Iborra, Telecommunications, Spain

The program is really a masterpiece. It gives you everything you need, very accurate, very fast. It's really what every Electrical Engineer dreams of. It's so easy to use and it does everything! DC, AC, Transient analysis, Thévenin, Bode plots… everything! I'm really amazed.
— Nikolaos Trichakis, EE major, Aristotle University of Thessaloniki, Greece

I wish I had it while going through school.
— Joe Riel, BSEE, creator of Syrup (a symbolic circuit simulator for Maple V), University of California, Irvine, USA

Congratulations for your program: it's simply fantastic. Symbulator is worth the cost of a TI-89!
— Pier Giorgio Raponi, engineering student, Pisa, Italy

You've made an excellent program. Symbulator is really the best circuit simulator ever made for a calculator.
— Rui Sebastião, EE major, University of Coimbra, Portugal

Symbulator is probably the most useful program ever made for a TI calculator. I am an electronics student and even paid for the EE*Pro software, yet I find myself using Symbulator more because it is much better at what it does.
— Josh Cunningham, electronics major

Symbulator, by far, has been the best tool for EE I have come across yet. […] It is truly an impressive piece of work. You should be proud. It certainly is helping me to focus on my studying of EE instead of trying to remember all the math.
— Jim Wachtel, EE, Process Control & Electrical Co., St. Louis, Missouri, USA

Licence

From June 2013, Symbulator was offered under a Creative Commons BY-NC-SA licence. Since 2026 it is open source under the MIT licence, which supersedes it. If you want to port it to another platform, you are free to do so, provided the copyright notice and the attribution of authorship travel with it.