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Comment: Wrong algorithm (Score 2) 90

by MathiasRav (#39838499) Attached to: NASA's Interactive Flood Maps

The map is wildly inaccurate. Look at this gravel pit near Petersburg, VA: Because the pit is close to sea level, the map claims it will be flooded at a 2 m sea level rise. In reality, it would probably take a 60 m sea level rise for it to flood because of the height of the surrounding terrain.

It looks like NASA just did a plane intersection with the terrain. If the height above sea level at this point is lower than a threshold, then they claim it will be flooded when the sea rises to this threshold. This is the reason why the Netherlands seems to be all flooded on the map - dams are completely ignored by this algorithm.

Look at a sea level rise map of the same gravel pit in a calculation that takes the global terrain into account. You need to set the water level to 60 m for the sea to spill over into the gravel pit.

Comment: Paper Rules (Score 2) 292

by MathiasRav (#35428300) Attached to: Can You Beat a Computer At Rock-Paper-Scissors?

For an intro (and I mean intro) course in Computer Science at uni, we were assigned to write a Java client in a game called Paper Rules. Establish TCP connection, wait for the master server to find an opponent (another client) for you, and then repeatedly send either ROCK, PAPER or SCISSORS to the server and read the result of the match. To make it interesting, the rules were enhanced so winning a round yielded 1 point, losing -1 point, except when paper won, in which case 2 points were assigned to the winner and -2 to the loser. Our task was to write an "AI" to outsmart the other students' AI.

I wrote a simple algorithm that kept track of the statistics for each of the 18 combinations of [my choice in round n, round n result, opponent's choice in round n+1] and chose based on what the opponent had picked the most in the past. In a match, the winner was declared after 1000 rounds.

Of course, the so-called PaperServer was a <1000-SLOC inefficient by-students-for-students Java one-system-thread-per-connection server running in a Java VM inside a Java VM (yes, really - an IDE called BlueJ) on a terribly underpowered virtual server, so it didn't last long, and anything educational was lost on us that day. Fun times.

Comment: Re:Roboticus Superioritis (Score 1) 54

by MathiasRav (#33162406) Attached to: Swinging Robot Excels At Wall-Climbing

I no longer login because I feel that while attacking a company's products is fair game (specifically Apple), having stories singling out their users as "selfish" and unkind is not "news for nerds stuff that matters". Am I an Apple fanboi? Let's just say I've used NIX for decades (yes I'm old) and I'm not talking OS X.

You know, registered users can have signatures.

Comment: Useless (Score 1) 150

by MathiasRav (#32350020) Attached to: Secure Communication Comes To Android
Encrypted voice is US only, so that's no good for the rest of the world. Also, searching for TextSecure on Market doesn't yield any results on my Android 1.5 device (although the FAQ claims it works on all versions of Android), though 2.2 is fine. Sending encrypted texts to myself didn't work either, it says "Bad encrypted message..." but that might just be me doing something wrong.

"If it ain't broke, don't fix it." - Bert Lantz

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