tbensky

https://www.youhere.org: "Want to know who showed up?" is the tag line. It's an app-based attendance service for teachers/coaches/band directors/conference organizers, etc. I'm a teacher and it scratches an itch I had (students not showing up to class). Been hitting the $500/month more and more often now (even after server fees).

Hi! Thanks for trying it. The "slow sway" is part of the plan! It's so the oversized first row of a qwerty keyboard can show all possible letters on the top row. If it feels too much like a game, slow it down using the main app from your home screen.

I have a lot of trouble texting, independent of the issues here. I'm just clumsy and can't seem to do it in any productive way.

I'm working on this keyboard substitute with larger keys and split up keyboards: https://apps.apple.com/us/app/icantext/id6748927092. Give it a try if you want.

One of my favorite retro projects in this real-time TRS-80 (Model I assembler and emulator that assembles and runs Z80, literally with each key press. Mind boggling how today's CPUs can emulate and entire 8-bit computer dev-process all between key presses in a browser. https://www.teamten.com/lawrence/projects/assembly-language-...." The author even says "How about: With every keystroke in the IDE’s code editor, we assemble the whole program, reset a virtual TRS-80 to a known state, install the program, and run it??

Uni. prof here/shameless plug: I developed a general education class for college students about the 'history of navigation' which includes the science behind navigation and why clocks and (accurate) timekeeping are needed for navigation. I wrote a book about it all I use for the class, if anyone's interested: https://www.amazon.com/Longitude-Time-Navigation-Tom-Bensky-.... I was inspired by Sobel's book, but I needed more math and science in the discussions.

Also, if you can find the book by Williams called "From Sails to Satellites: The Origin and Development of Navigational Science" you'll laugh out loud at his wit about navigation throughout the book.

I work on neural nets back in the mid 1980s, so I was somewhat familiar with their structure, backpropagation, squashing functions, etc. I wanted to get back into them, so I started by rederiving all backprop formulas by hand here https://github.com/tbensky/NeuralNetworks/blob/main/Backprop....

Then I wrote up a NN from scratch in Python to train some simple vectors and even got it to train some MNIST characters https://github.com/tbensky/NeuralNetworks/blob/main/ANN/ann.... (but it was slow).

With that basic refresher, I got into PyTorch and worked on training a PiNN: https://github.com/tbensky/PiNN_Projectile (neat video of it training: https://youtu.be/0wlHa1-M7kw).

Now I'm working on understanding kernels with CNNs (this is my question, I'm making good progress on answering): https://ai.stackexchange.com/questions/46180/kernels-on-a-tr....

Having loads of fun!

Take a look at the Finch robot: https://www.birdbraintechnologies.com/products/finch-robot-2.... Version 2.0 has really evolved and is quite nice.

Back during the pandemic, hardware-based contract tracers were an idea. I built one using the ESP32; see https://github.com/tbensky/npct. In a nutshell, everyone generates a (non-centralized) hash for themselves based on local entropy. This hash is set to the BLE name of the ESP32. Turn it on and throw it in your backpack as you go out. When two ESP32s pass by each other, they both log the other's BLE name (hence hash). Later on, hash logs could be inspected and uploaded to a central server so you can see who encountered who. Seems like there's still some (non-Covid) applications for this (but I can't think of any). Fun project. Learned a lot about Bluetooth.

Back in the early days of Linux (~1993) or so, I was trying to convince my workgroup in grad. school that Linux was a nice alternative for running our numerical simulations (in C). But I knew I had to get the graphics working, since no one wanted to use a text-only interface. It was a Dell PC using some graphics card; the word 'tulip' is in the fog of my memory. The graphics driver was not loading, giving some error about a reference not being found in the .o file. I didn't know what to do, so I loaded up the .o file in vi, searched for the offending reference, edited it out and saved the .o file. From then on the graphics works great!

XRF=x-ray fluorescence. You shoot X-rays into a metal, typically the gamma rays from an Am-241 source. This causes atoms in the metal to fluoresce their own gamma rays that are a (somewhat) unique signature of the atom itself. So in sum, XRF allow one to non-destructively determine the atomic constituents of a bulk material (but 'heavy' materials..heavier than Silicon for example).

Hello and thanks for our interested. There's a paperback version here: https://www.amazon.com/Longitude-Time-Navigation-Tom-Bensky/... (same ed. as the Kindle version).

Happy to see this post on HN. As a college prof, I've spend many years studying the history of 1700s navigation and taking student groups to Greenwich to see and study H1 (H2, H3 and H4). I love these clocks and all of the stories behind them. The serious enthusiast will find a lot of technical details on the Harrison's clocks in this book https://www.amazon.com/Marine-Chronometers-Greenwich-Catalog... and this one https://www.amazon.com/Marine-Chronometer-Its-History-Develo.... I've also collected all of my pedagogy on 1700s navigation into a this book: https://www.amazon.com/Longitude-Time-Navigation-Tom-Bensky-... where I dive somewhat into the innards of H1. To answer another post: H1 has been fully disassembled and reassembled with XRF done throughout.

I remember using Turbo Lightning. It was incredible. You type a word in some DOS program, and when you hit the spacebar, a beep would sound if the word was spelled wrong. Back then Peter Norton was all the rage, so if you typed "Norton" TL would beep and suggest spellings like "notion, nothing, etc." to correct Norton. The suggestions felt so AIish and futuristic to me. Wow a "suggestion" for how to spell something? If you selected a replacement, it would stuff the keyboard buffer with backspaces, to erase the word, and retype the correction. Borland made incredible software back then. Great times.

Hi everyone. I see a lot of neat web-based IDEs on HN for simple coding, like EndBasic, EasyLang, etc. I always like trying these out, but feel like they all lack a reason to use them--in other words, to keep me using them, I wish they'd offer some themed lessons that I can do to try out coding with these platforms. Take EndBasic. I launch the interpreter in my browser. It looks cool and reminds me of a TRS-80 from the 1980s. But now what do I do now?

Anyway, throwing my hat in the ring: https://codebymath.com. Lots of small mathematical problems that can be solved using code. (Started this a few years ago to help teach a home-school group about coding, that was tied to lessons from their math class.)

I like the clpfd approach too:

:- use_module(library(clpfd)).

go(L) :- L = [Vixen, Rudolph, Prancer, Dasher, Comet, Dancer, Donder, Blitzen, Cupid], L ins 1..9,

        % Vixen should be behind Rudolph, Prancer and Dasher,
        maplist(#>(Vixen),[Rudolph,Prancer,Dasher]),
        
        %  Vixen should be in front of Dancer and Comet.
        maplist(#<(Vixen),[Dancer,Comet]),

        % Dancer should be behind Donder, Blitzen and Rudolph. 
        maplist(#>(Dancer),[Donder,Blitzen,Rudolph]),
        
        % Comet should be behind Cupid, Prancer and Rudolph.
        maplist(#>(Comet),[Cupid,Prancer,Rudolph]),

        % Donder should be behind Comet, Vixen, Dasher, Prancer and Cupid. 
        maplist(#>(Donder),[Comet, Vixen, Dasher, Prancer,Cupid]),

        % Cupid should be in front of Comet, Blitzen, Vixen, Dancer and Rudolph
        maplist(#<(Cupid),[Comet, Blitzen, Vixen, Dancer,Rudolph]),

        % Prancer should be in front of Blitzen, Donder and Cupid.
        maplist(#<(Prancer),[Blitzen,Donder,Cupid]),

        % Blitzen should be behind Cupid 
        Blitzen #> Cupid,

        % but in front of Dancer, Vixen and Donder.
        maplist(#<(Blitzen),[Dancer,Vixen,Donder]),

        % Rudolph should be behind Prancer
        Rudolph #> Prancer,
        
        % but in front of Dasher, Dancer and Donder.
        maplist(#<(Rudolph),[Dasher,Dancer,Donder]),

        % Finally, Dasher should be behind Prancer
        Dasher #> Prancer,

        % but in front of Blitzen, Dancer and Vixen.
        maplist(#<(Dasher),[Blitzen,Dancer,Vixen]).

I also would like to echo the thank you to Markus. His Power of Prolog videos have taught me so much about Prolog. His recent one on DCGs is incredibly eye-opening.

Fun exercise in Prolog too: https://www.codebymath.com/index.php/welcome/lesson/prolog-d....

In the book "The lost art of finding our way" the author claims a big boost to not getting lost is to (simply) pay more attention to an outing as it evolves. It is indeed difficult to suddenly, half way through a trip (to a dense city, hiking trail, or whatever) answer the question "where am I?"

I've been using Prolog on and off for 20+ years (I actually bought and used Turbo Prolog by Borland under MS-DOS). I have to confess though, I've never quite understood Prolog or what it's for. I've followed Markus Triska and his Power of Prolog videos (watched all of them). I'd like to thank him for his work. This fellow is super smart about programming, and he appears to be singlehandedly re-inventing Prolog. His videos are of the highest quality content. I've learned so much from his work, particularly in the area of CLP. I've now come to understand Prolog as a search language, and he's convinced me that CLP+Prolog are the next generation of Prolog as compelling tool. (I do a bunch of work in personnel scheduling/optimization and have mostly used genetic algorithms to this point. I'm seeing more and more uses of Prolog in this area thanks to Mr. Triska.)

The Tau Prolog (http://tau-prolog.org) system (written in JS) is used here https://www.codebymath.com/index.php/welcome/lesson_menu#pro... to use Prolog as a way of teaching mathematical concepts.

Yes, multi-threads of it...that would be scary!

THANK YOU for giving us Selenium. When I first ran my script and saw the browser pop up start "running on it's own," I was pretty wowed.

Ah yes, the genetric algorithm (GA). Well, in short, scheduling personnel is a very visible, policital, and important job. It affects people's lives, and has to be done farily and correctly. I did my best (by hand) for a few years (scheduling 50ish professors into 200 class sections), and I knew I was doing a bad job, but had no choice. It would take 2 weeks to do, because I could only mentally handle working on such a job for so much in a given day before I had to set it aside. So I came up with a preference form, that each could fill out dealing with things like preferred time of the day to teach, daily schedule compactness, preferred class levels, etc. These preferences could also be weighted (0..1) by importance to each person. So the GA starts out with a long, two-part inital random sequence that consists IDs to all professors followed by IDs to all possible classes. Using crossover and mutation (the usual GA steps), the order of the professor IDs vs the order of the classes (prof 0 gets class, prof 1 gets class 1, etc.) are shuffled by the GA. (There are a lot of strange constraints to this you'd only see in academia, related to pay, and contractual teaching requirements.) A fitness is calculated for each professor's latest schedule, by computing a weighted sum of their preferences, based on the assigned classes pulled from the long GA sequence. It's incredible how well it works. It is done in under an hour, people seem happy, everyone's schedule fitness is minimzed, and each's schedule fitness is explained to them (i.e. you got +3 points because you wanted an 8am class, and got one). Everyone can also see everyone else's fitness so it's a "share the pain" kind of resulting schedule. At times when we go in to tweak things by hand, it is clear how tightly the GA optimized things, as any human intervention we try usually and obviously makes things worse. Bottom line, the GA generates the CSV, which Selenium types into PS. After using the GA, I'm convinced that neither humans (or spreadsheets) should be invovled in scheduling at all. I also think GAs are also pretty incredible.