Robert Cunningham's Blog

Julia's CUDA.jl is famous for letting you run pure Julia on GPUs. This seems impossible, because Julia feels like a scripting language, but it works as advertised: fast and simple with no DSLs or C++ required [0]. Here's an example where we write and execute a CUDA kernel that

Every day, you attend a horse race between three horses. The bookie is giving fair 50%/30%/20% odds (i.e., if the third horse wins they return 1/20% = 5x), but you have inside information and know that the real chances are 70%/20%/10%. You have \$1000 total

This semester I took 18.404 ("Theory of Computation"). It's widely known as being among the best classes at MIT. 18.404 vis-a-vis 1100 other classesProf. Sipser teaches 18.404 in the standard format, with eighty minute lectures on Tuesdays and Thursdays. Perhaps it's because the format is standard that

I tie my raincoat around my waist shortly after we leave. With hard enough rain you get wet, raincoat or not. Might as well feel the rain on your skin. I let the rain soak through my hair, which hangs down in front of my eyes. I can sweep it

Hey! The purpose of this series is to teach you how to design, manufacture, and program a circuit board. Afterwards, you'll be well positioned to work on a simple circuit board that drives something like bluetooth headphones, a quadcopter, or an electric skateboard. My first circuit board <3 (and

What's a rock like granite really made of? It turns out that granite is a mix of two minerals, quartz and feldspar. You can see the individual specs of each if you look closely. The whitest speckles are quartz. The beige speckles are feldspar. The black specs are something else,

I've been deploying a bunch of web apps recently, and it turns out there's one pattern that's so common it might even be called classic. Basically: Each subdomain should get routed to its own docker container. blog.example.com should hit a blogging container, app.example.com should hit a

This post explains call/cc, which is a control flow operator that works like a time machine. Although call/cc is native to the Scheme family of languages, I explain it here with the more widely-accessible TypeScript syntax. call/cc is particularly unusual because you can use it to implement

Disclaimer: this is definitely not legal advice and I am neither a lawyer nor your lawyer. I dreaded cancelling my first LLC for an entire year. In the end, it wasn't nearly as complicated as I had imagined. This post outlines the steps you should follow to shut down your

My fourth semester at MIT is ending, which means it's time for me to take a moment to think about the classes that I took. I'll say a few words about what each class is, why I took it, what I got out of it, and what I thought of

Imagine you're a trader in medieval Europe, looking for a way to defend yourself. You can choose among three weapons. First, there's the dagger. You stick it in your pocket, and when you see someone dangerous on the street, you whip it out, stab them, and run away. Maybe you

Here's something I realized last year: it's OK to be vegetarian because you don't like the idea of killing animals. For much of my life I've had two reasons for being vegetarian: a real one and a fake one. Here's the real reason: there was a moment when I realized

Today I cleaned out my childhood dresser. There were 79 t-shirts in there, from every activity I've ever done. Almost all of them reflected my desire for status. Shirts from schools that admitted me. Shirts from events I won. Shirts from groups that I wanted to feel included in. Shirts

Imagine a foreign planet with three legged chickens, two suns in the sky, exotic megafauna, and pink trees everywhere. Crazy, right? But wait, we have pink trees on earth. You just have to stop and notice them.

I realized over the summer that I still didn't have a clear picture of who I wanted to be. Here's a procedure I used to help uncover the answer. Make a list of a hundred or so people that seem interesting. Lean towards over-including. My list has parents, presidents, teachers,

Here's a realization I had the other day. Nobody's job title is to "make cool stuff happen." When cool stuff happens, it's because someone just like you and me made it happen. And if you want to continue the cycle, you need to make stuff happen. There's a scene in

The Enneagram is a way of dividing personalities into 9 types, sort of like the MBTI. It's totally unscientific, but very much worth learning if you care about understanding people. The Enneagram feels a bit like the color wheel of personality. Knowing the color wheel gives structure to your observations

I noticed yesterday that suppressing emotion has a bodily sensation. It shows up in my sternum when something sad or frustrating happens. My chest muscles tighten, squeezing in a breath, and yet my throat feels open and wide. There's a straining sensation in the top of my throat: my body

Welcome! The point of this tutorial is to teach you how to use Mathematica for menial algebra and calculus. Fluency in Mathematica has encouraged me to think at a layer of abstraction above algebra, which has increased my enjoyment of courses with a tiresome amount of it. I hope it

The Stoics suggest that if you have something you really enjoy, you should give it up occasionally. This helps you to more fully appreciate having the thing. For example, if you have a warm winter coat, occasionally walking around without it will make you appreciate it more. This got me

MIT has an introductory programming subject called 6.009 ("six double-oh nine"). Its title is "Fundamentals of Programming," and it's a remarkable class. 6.009 is remarkable because it teaches people how to code. There's no theory to cram and flush. Lectures are effectively optional. But the problem sets are

I have two kinds of problems, the urgent and the important. The urgent are not important, and the important are never urgent.Each year on my birthday, I pull up time.is and quietly watch it tick from 11:59:59 to 12:00:00. This moment is quite emotional,

When I was in middle school, I spent a ton of time playing video games. One of the many I played was a mobile MMORPG. It was wholly unexceptional, but delightful in the way that all MMORPGs are: you fight stuff, level up, buy some items, fight more stuff, and

Last year, I named a project 'Cydr' (read 'cite-r'). I loved the name. It was clever, short, and had a sexy startup vibe to boot. It turned out to be a disaster of a name. You always had to spell it when chatting with people. And then, because the spelling

There's natural (almost foregone) conclusion that a university's acceptance rate is inversely proportional to its quality: low acceptance rate represents high quality, and vice versa. The other day, I realized that this metric is much more easily manipulated than I had previously thought. Here's an illuminating example. In a town