Jack Crenshaw is the proverbial Jack of many trades, master of a few. He wants to share what he knows, and that’s one of the reasons this site exists.

Jack wrote his first computer program in 1956, his first dynamic simulation (for NASA) in 1959, and engineered his first embedded system in 1975. For NASA and Project Apollo, he did seminal work on the circumlunar trajectory (the now-familiar “Figure-8″ free return trajectory) and abort trajectories (fast return). He’s continuing that work to this day, for Part-Time Scientists, one of the Google Lunar X-Prize teams.

For trajectory analysis, he pioneered the use of unified two-body orbit formulations now known as universal variables. He also pioneered the use of quaternion mathematics for attitude control analysis and simulations.

Jack specializes in the application of advanced methods of math and physics to the solution of real, practical problems. He is the author of the book, Math Toolkit for Real-Time Programming and the column, Programmer’s Toolbox in Embedded Systems Development Magazine (now on line at EEtimes and linked as Embedded.com). Several years ago he wrote the on-line tutorial series Let’s Build a Compiler. You can find a wonderful update of the tutorial at Pascal Programming for Schools (PP4S). You can learn more about Jack and his views in interviews here and here.

All work and no play could make Jack a dull boy, but he’s not in much danger of that. Jack has many hobbies and interests, ranging from auto and motorcycle racing to physical sports like swimming, diving, gymnastics, and water-skiing to analog and digital electronics. He’s a music lover who was bitten by the “hi-fi” bug in 1955, He collects and repairs vintage vacuum-tube electronics, mostly Heathkits. See more about Heathkits here and here.

Jack is an animal lover.  Aside from the family pets (dogs and parrots), he .has raised many wild and domestic birds, including songbirds, pigeons and doves, ducks, geese, chickens, etc. His favorite songbird is the bluejay, and his favorite water bird, the Muscovy duck.  He and wife Toney have also kept and raised horses, goats, sheep, and one bull.  See more about them here and here. Expect to see many stories about all these remarkable critters in this site.

5 thoughts on “About

  1. Hi Jack

    Not sure where to post this, so sorry if this is inappropriate.

    I’ve been writing a lexer and parser recently and I was having trouble getting my old brain in gear until I read your excellent series of articles “Let’s Build a Compiler!”. I just wanted to thank you, publicly.

    I was also encouraged to read your post on “Science vs. Religion” as I’m a Christian who used to be an atheist, until I seriously considered the evidence for the resurrection. I hope you’ve read C.S. Lewis’s excellent book “Miracles” as I think you’d enjoy it. Similarly, almost anything by the British mathematician and Christian John Lennox is worth reading for his clarity of reasoning.

    All the best,

  2. Hello Jack, I have been trying to send you an email, but each time I get an error message back about relaying not permitted. So I sent the message to your Linkedin account. I really hope to be able to get in touch with you, in particular because of your excellent compiler series.

    – Frank

  3. Jack,

    “One thing you can say about folks from the South: We know how to enjoy life.” Living in Canada, at first I took offence. Then I read further and realized you were not claiming superiority over folks from Northern Ontario in life-enjoyment, so all is well.

    Northern enjoyment for the body: On a cold winter night splash water on the hot sauna stove until it’s nearly unbearable, then run outside and jump in the snow, looking up at the diamonds, then back into the sauna again and repeat.

    Northern enjoyment for the soul: At that most melancholy time of day, just before the stars come out, build a fire on the shore of a remote lake. The call of the loons, punctuated by the snap of the logs on the fire are a reminder of our true place.

    Perhaps we identify more with melancholy music as well:

    From your kind and generous comments about Katherine Johnson, I infer that you are true Southern Gentleman…

    1. Sorry, John, I certainly meant no offense to anyone. And I must admit that your image of a fire on the shore of a remote lake sounds delightful — as long as I can bring my electrically heated socks ;-). As a matter of fact, I’ve spent nights in a tent on Lake Jordan in Alabama. The only difference is, instead of the call of the loons, it was more about the buzz of the mosquitoes. Anyhow, our summers on the lake tended more to swimming, diving, water-skiing, boating, and such. And usually, the roar of engines somewhere nearby.th

      My comment about fun reflects my experiences working in Philadelphia and Michigan, or visiting in NYC. People there seemed SO focused on their work and careers. Not much time for fun & games when you’re shoveling snow twice a day.

      I DO love music of all kinds except rap and some country. But my favorites tend to run more towards crashing cymbals and blaring trumpets. Stan Kenton and Tchaikovsky come to mind.

      Thanks so much for sharing.

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