Sorting algorithms visualized Nov 13 2013
This video visualization of 15 different sorting algorithms is mesmerizing. (Don't forget the sound.)
This video visualization of 15 different sorting algorithms is mesmerizing. (Don't forget the sound.)
Black Perl is a poem written in valid Perl 3 code:
BEFOREHAND: close door, each window & exit; wait until time.
open spellbook, study, read (scan, select, tell us);
write it, print the hex while each watches,
reverse its length, write again;
kill spiders, pop them, chop, split, kill them.
unlink arms, shift, wait & listen (listening, wait),
sort the flock (then, warn the "goats" & kill the "sheep");
kill them, dump qualms, shift moralities,
values aside, each one;
die sheep! die to reverse the system
you accept (reject, respect);
kill the next sacrifice, each sacrifice,
wait, redo ritual until "all the spirits are pleased";
do it ("as they say").
return last victim; package body;
exit crypt (time, times & "half a time") & close it,
select (quickly) & warn your next victim;
AFTERWORDS: tell nobody.
wait, wait until time;
wait until next year, next decade;
sleep, sleep, die yourself,
die at last
# Larry Wall
It's not Shakespeare, but it's not bad for executable code.
From Stack Overflow, a question about how to efficient sort a pile of socks.
Yesterday I was pairing the socks from the clean laundry, and figured out the way I was doing it is not very efficient. I was doing a naive search -- picking one sock and "iterating" the pile in order to find its pair. This requires iterating over n/2 * n/4 = n^2/8 socks on average.
As a computer scientist I was thinking what I could do? sorting (according to size/color/...) of course came into mind to achieve O(NlogN) solution.
And everyone gets it wrong. The correct answer is actually:
1) Throw all your socks out.
2) Go to Uniqlo and buy 15 identical pairs of black socks.
3) When you want to wear socks, pick any two out of the drawer.
4) When you notice your socks are wearing out, goto step 1.
An extensive collection gathered from all over the internet of the source code and documentation for NASA's Apollo and Gemini programs. Here's part of the source code for Apollo 11's guidance computer.
And here's an interesting tidbit about the core rope memory used for the Apollo's guidance computer:
Fun fact: the actual programs in the spacecraft were stored in core rope memory, an ancient memory technology made by (literally) weaving a fabric/rope, where the bits were physical rings of ferrite material.
"Core" memory is resistant to cosmic rays. The state of a core bit will not change when bombarded by radiation in Outer Space. Can't say the same of solid state memory.
Woven memory! Also called LOL memory:
Software written by MIT programmers was woven into core rope memory by female workers in factories. Some programmers nicknamed the finished product LOL memory, for Little Old Lady memory.
For her yearly month-long project at Slate, Annie Lowrey wanted to learn how to code. She picked Ruby and became interested in the story of _why, the mysterious Ruby hacker who disappeared suddenly in 2009. In a long article at Slate, Lowrey shares her experience learning to program and, oh, by the way, tracks down _why. Sort of.
The pickaxe book first shows you how to install Ruby on your computer. (That leads to a strange ontological question: Is a programming language a program? Basically, yes. You can download it from the Internet so that your computer will know how to speak it.)
Then the pickaxe book moves on to stuff like this: "Ruby is a genuine object-oriented language. Everything you manipulate is an object, and the results of those manipulations are themselves objects. However, many languages make the same claim, and their users often have a different interpretation of what object-oriented means and a different terminology for the concepts they employ."
Programming manual, or Derrida? As I pressed on, it got little better. Nearly every page required aggressive Googling, followed by dull confusion. The vocabulary alone proved huge and complex. Strings! Arrays! Objects! Variables! Interactive shells! I kind of got it, I would promise myself. But the next morning, I had retained nothing. Ruby remained little more than Greek to me.
Very much trying not to read the entirety of this beginner's guide to developing iOS apps published by Apple because then I'll be tempted to actually make one.
Codify is an iPad app that allows you to code iPad games on your iPad.
We think Codify is the most beautiful code editor you'll use, and it's easy. Codify is designed to let you touch your code. Want to change a number? Just tap and drag it. How about a color, or an image? Tapping will bring up visual editors that let you choose exactly what you want.
Codify is built on the Lua programming language. A simple, elegant language that doesn't rely too much on symbols -- a perfect match for iPad.
SUPER ugly, but it works
Added a bunch of semi colons that were missing for some balls weird reason.
Oops, left some debugging crap
We lost a tech giant today. Dennis MacAlistair Ritchie, co-creator of Unix and the C programming language with Ken Thompson, has passed away at the age of 70. Ritchie has made a tremendous amount of contribution to the computer industry, directly and indirectly affecting (improving) the lives of most people in the world, whether you know it or not.
These sorts of comparisons are inexact at best, but Richie's contribution to the technology industry rivals that of Steve Jobs'...Richie's was just less noticed by non-programmers.
An extensive side-by-side reference sheet of four scripting languages (PHP, Python, Perl, and Ruby) with which you can compare how the different languages handle variable declarations, concatenations, objects, and hundreds of other things. Great cheatsheet for learning a new language when you're already familar with one of the others.
From Wikipedia, a list of unusual software bugs, including the Mandelbug and Heisenbug. My favorite is the Schrödinbug:
A schrödinbug is a bug that manifests only after someone reading source code or using the program in an unusual way notices that it never should have worked in the first place, at which point the program promptly stops working for everybody until fixed.
On text2re.com, you can input some text you want to use a regular expression on, click on what you want to match, and it'll generate the regular expression for you.
This system acts as a regular expression generator. Instead of trying to build the regular expression, you start off with the string that you want to search. You paste this into the site, click submit and the site finds recognisable patterns in your string. You then select the patterns that you are interested in and it writes a fully fledged program that extracts those patterns from that string. You then copy the program into your editor or IDE and play with it to integrate it into your program.
This just totally broke my brain.
Andre Torrez offers some advice for those who think that they can clone a popular web app over the weekend. The best part -- or the worst, if you're the aspiring weekend programmer -- is that each item on the list is a little Pandora's box of Alice's rabbit holes. Like this:
Lost password flow. You'll want to generate a key and store it someplace for when someone requests to reset their password. So that's another email that has to go out.
If you actually want your email to arrive at its destination, you're gonna have to worry about all this. Or go through a third-party service, which is another interface (and bill (and moving part)) that you need to worry about. You get the point...making a web app work for more than just one person is hard, way harder than it looks unless you've done it.
Ok, so it's not Gaga (and certainly not Christopher Walken), but she does work "object oriented" into the lyrics.
This is possibly the best production of the worst idea I've ever seen.
Charles Babbage built one of the first mechanical calculating machines but Ada Lovelace was the first to show how the machine's arithmetic function could be abstracted to produce things other than numbers: language, graphics, or music.
There are several other Information Pioneers shorts available on Vimeo, including profiles of Tim Berners-Lee, Alan Turing, and Hedy Lamarr.
From a bunch of security experts, the top 25 most dangerous programming errors that can lead to serious software vulnerabilities.
Cross-site scripting and SQL injection are the 1-2 punch of security weaknesses in 2010. Even when a software package doesn't primarily run on the web, there's a good chance that it has a web-based management interface or HTML-based output formats that allow cross-site scripting. For data-rich software applications, SQL injection is the means to steal the keys to the kingdom. The classic buffer overflow comes in third, while more complex buffer overflow variants are sprinkled in the rest of the Top 25.
A programmer lists 20 lessons learned in the past 20 years.
5. You are not the best at programming. Live with it. -- I always thought that I knew so much about programming, but there is always someone out there better than you. Always. Learn from them.
In mid-September I purchased a shiny new 24" Apple iMac and an iPhone 3GS. I signed up for the Apple iPhone Developer Program. I bought some books and started doing the tutorials, step by step. I came up with the idea for an app I needed and built a prototype, then plunged in and started creating a full app that would be good for others, too.
Personally, I find this really inspiring.
Hackers Can Sidejack Cookies, a poem by Heather McHugh.
to creeping featuritis
are banana problems.
("I know how to spell banana,
but I don't know when to stop.")
After writing The Cat in the Hat in 1955 using only 223 words, Dr. Seuss bet his publisher that he could write a book using only 50 words. Seuss collected on the wager in 1960 with the publication of Green Eggs and Ham. Here are the 50 distinct words used in the book:
a am and anywhere are be boat box car could dark do eat eggs fox goat good green ham here house I if in let like may me mouse not on or rain Sam say see so thank that the them there they train tree try will with would you
From a programming perspective, one of the fun things about Green Eggs and Ham is because the text contains so little information repeated in a cumulative tale, the story could be more efficiently represented as an algorithm. A simple loop would take the place of the following excerpt:
I do not like them in a box.
I do not like them with a fox.
I do not like them in a house.
I do not like them with a mouse.
I do not like them here or there.
I do not like them anywhere.
I do not like green eggs and ham.
I do not like them, Sam I am.
But I don't know...
foreach (\$items as \$value) doesn't quite have the same sense of poetry as the original Seuss.
72 g haricot beans
108 g lard
111 cups oil
119 ml water
114 g red salmon
100 g dijon mustard
Put potatoes into the mixing bowl. Put dijon mustard into the mixing bowl. Put lard into the mixing bowl. Put red salmon into the mixing bowl. Put oil into the mixing bowl. Put water into the mixing bowl. Put zucchinis into the mixing bowl. Put oil into the mixing bowl. Put lard into the mixing bowl. Put lard into the mixing bowl. Put eggs into the mixing bowl. Put haricot beans into the mixing bowl. Liquefy contents of the mixing bowl. Pour contents of the mixing bowl into the baking dish.
Read in the right way, Strunk and White's The Elements of Style becomes an important reference for software development.
5.21. Prefer the standard to the offbeat
Young writersInexperienced programmers will be draw at every turn toward eccentricities in language. They will hear the beat of new vocabulariesabstractions, the exciting rhythms of special segments of their societyindustry, each speaking a language of its own. All of us come under the spell of these unsettling drums; the problem for beginners is to listen to them, learn the words, feel the vibrations, and not be carried away.
A guy who started working as a game programmer for Atari when he was 21 years old recounts his experiences, notably his work on the Donkey Kong cartridge.
Basically, Atari's marketing folks would negotiate a license to ship GameCorp's "Foobar Blaster" on a cartridge for the Atari Home Computer System. That was it. That was the entirety of the deal. We got ZERO help from the original developers of the games. No listings, no talking to the engineers, no design documents, nothing. In fact, we had to buy our own copy of the arcade machine and simply get good at the game (which was why I was playing it at the hotel - our copy of the game hadn't even been delivered yet).
The programmers profiled in the 1986 book, Programmers at Work...where are they now?
Bill Gates. Then: founder of Microsoft, popularizer of the word "super". Now: richest guy in the world. After a stint in the 90s as pure evil, semi-retired to focus on philanthropic work.
An extensive collection of cheat sheets for programming languages and applications. There are 10 PHP cheat sheets alone and more for related things like Drupal and CakePHP.
Casey Reas and Ben Fry, inventors of the Processing programming language (that's Proce55ing to you old schoolers), have just come out with a book on the topic that looks fantastic. In addition to programming tutorials are essays and interviews with other heavy hitters in the programmatic arts like Golan Levin, Alex Galloway, Auriea Harvey, and Jared Tarbell. The site for the book features a table of contents, sample chapters, and every single code example in the book, freely available for download. Amazon's got the book but they're saying it's 4-6 weeks for delivery so I suggest hoofing it over to your local bookstore for a look-see instead.
Update: I corrected the above statement about Perl et. al. not existing and modified it to read that they didn't make the list. Perl, Ruby, nd Java all existed in one form or another in 1995. (thx to everyone who sent this in)
I was telling a friend this weekend about an article I'd read long ago about Larry Wall approaching the development of Perl as if it were a natural language. I think this is the article in question. Perl, the first postmodern computer language and a conversation with Larry Wall also touch on Perl and linguistics.
Update: Here's the original post to comp.lang.perl.misc by Wall. (thx, marc)
Ken Thompson built a backdoor into the "login" Unix program by inserting commands into the C compiler that ensured that not only would the backdoor code be inserted into the login program, but also into the C compiler itself when compiled.
Some of the onscreen special effects on Doctor Who were generated by a home computer called the BBC Micro. "A brief sequence during this program actually showed the BBC Basic and assembler code used to create the console display"
Bakeoff! A Gladwell article from back in September on a project that used different team methodologies to attempt to create the perfect cookie: an open source approach, an approach based on extreme programming, and a traditional hierarchical team. You may be surprised which team won.
We ran across the nerdiest board game today called c-jump, the computer programming game. More info: "Skiers and snowboarders line up at the start location and race along the ski trails. Spaces on the board show statements of programming language. First player to move all skiers past the finish line is the winner."
Update: here's the game's web site. "This game eliminates intimidation of many kids and their parents, bored by the mention of 'computer programming', often associated with visions of geeky guys glued to their computers."
Here's a story that mentions that Slashdot commenter that outsourced his job. "About a year ago I hired a developer in India to do my job. I pay him $12,000 out of the $67,000 I get. He's happy to have the work. I'm happy that I have to work only 90 minutes a day just supervising the code. My employer thinks I'm telecommuting. Now I'm considering getting a second job and doing the same thing."
Impressive demonstration of Ruby on Rails. "How to build a blog engine in 15 minutes with Ruby on Rails".
Processing, a programming environment for designers and artists, is in beta. It's the first public release.
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