Programming

The earliest memory I have of ‘programming’ is in the early/mid 90s when my father brought home a computer from work. We could play games on it … so of course I took the spreadsheet program he used (LOTUS 123, did I date myself with that?) and tried to modify it to print out a helpful message for him. It … halfway worked? At least I could undo it so he could get back to work…

After that, I picked up programming for real in QBASIC (I still have a few of those programs lying around), got my own (junky) Linux desktop from my cousin, tried to learn VBasic (without a Windows machine), and eventually made it to high school… In college, I studied computer science and mathematics, mostly programming in Java/.NET, although with a bit of everything in the mix. A few of my oldest programming posts on this blog are from that time.

After that, on to grad school! Originally, I was going to study computational linguistics, but that fell through. Then programming languages (the school’s specialty). And finally I ended up studying censorship and computer security… before taking a hard turn into the private sector to follow my PhD advisor.

Since then, I’ve worked in the computer security space at a couple of different companies. Some don’t exist any more, some you’ve probably heard of. I still program for fun too, and not just in security.

But really, I still have a habit of doing a little bit of everything. Whatever seems interesting at the time!

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Recent posts

A piece of the abc conjecture

2012-09-19

There’s been a bit of hubbub in the in the math world the last few weeks with Shinichi Mochizuki’s 500 page proof that of the ABC conjecture. Basically, the conjecture states that given three positive coprime integers a, b, and c such that a + b = c, the product of the distinct prime factors of a, b, and c is rarely much smaller than c. While this may sound strange, there are a number of interesting consequences that you can read about here.

To make a long story shorter, there was a challenge on Programming Praxis that intrigued me, which was to write code that given a upper bound on c would generate a list of all of the triples (a, b, c) such that the product is larger.

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Who wants to win the lottery?

2012-09-17

So everyone would love to win the lottery right? Just think of what you could do if you had even $1 million dollars to spend. You could buy a dozen tacos a day at Taco Bell for the rest of your life. And your children’s lives. And their children’s lives. 228 years to be more precise. Or you could pay to send the entire family from Cheaper by the Dozen to the average state university–even if they each took an additional two years to graduate. And that’s just for $1 million. Payouts are usually much higher than that…

So what’s the catch?

(If you came here just for the Powerball simulation, it’s down at the bottom of the page. Click here to go straight there.)

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A needle in a Pi-stack

2012-09-16

Recently I’ve been watching a lot of find-in-pi source code

(require racket/generator)

(define (make-pi-spigot)
  (generator ()
    (let loop ([q 1] [r 0] [t 1] [k 1] [n 3] [l 3])
      (if (< (- (+ (* 4 q) r) t) (* n t))
          (begin
            (yield n)
            (loop (* 10 q)
                  (* 10 (- r (* n t)))
                  t
                  k
                  (- (quotient (* 10 (+ (* 3 q) r)) t) (* 10 n))
                  l))
          (loop (* q k)
                (* (+ (* 2 q) r) l)
                (* t l)
                (+ k 1)
                (quotient (+ (* q (+ (* 7 k) 2)) (* r l)) (* t l))
                (+ l 2))))))

Simple enough to use, we can use Racket’s for to generate a list of n digits of pi or to convert the same to a string:

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Expanding L-systems

2012-09-15

An L-system is essentially a set of rewriting rules that turns a simple set of rules into a complex pattern. They’re generally used for generating self-similar fractals, including plant life, but I’ve also seen them used in programming languages research where they can generate valid programs given the grammar of a language. They’re also rather similar to turtle graphics in that many of the sample graphics that I’ve generated in the past are based directly off the L-systems page on Wikipedia. So this time I’ve decided to work on a relatively simple macro that can be used to expand simple L-systems.

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Optimizing Voronoi

2012-09-13

Starting with my previous post on Voronoi diagrams, I felt that I could do better. Sure, the code works well enough but it’s almost painfully slow. So let’s see if we can optimize it a bit.

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Generating Voronoi diagrams

2012-09-09

I was playing with image library and started to think about more ways that I could generate images. One idea that came to mind was to generate a bunch of colored points on the image and then color every other pixel based on which seed point was closest. Turns out, that’s exactly what a Voronoi diagramis… The Wikipedia article at least says that Voronoi diagrams can be traced back at least to Descartesin 1644, so I guess at least I’m in good company. 😄

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