Monday, May 23, 2016

Monday, May 16, 2016

Dean Karnazes: the man who can run for ever
When running, you break down glucose for energy, producing lactate as a byproduct and an additional source of fuel that can also be converted back into energy. However, when you exceed your lactate threshold, your body is no longer able to convert the lactate as rapidly as it is being produced, leading to a buildup of acidity in the muscles. It is your body's way of telling you when to stop – but Karnazes never receives such signals.

"To be honest, what eventually happens is that I get sleepy. I've run through three nights without sleep and the third night of sleepless running was a bit psychotic. I actually experienced bouts of 'sleep running', where I was falling asleep while in motion, and I just willed myself to keep going."

Monday, April 4, 2016

Will minimum wage hikes lead to a huge boost in automation? Only if we're lucky.
What about the workers thrown out of jobs by the new robo-waiters? Many would get new jobs, though the way this would work is often ignored.
  • Most restaurants would keep longer hours (they're paying for the rent and the robots anyway), meaning many workers would get a raise and change shifts.
  • The advanced robo-restaurant technology would itself be a valuable American export good, and people would be employed in designing and selling it.
  • Some low-wage work would be reallocated out of the relatively low-social-value restaurant sector and into things like child care and home health assistance, for which there is ample demand.
  • Since poor people are now making more money, there will be opportunities to sell them things — things like restaurant meals! — that they couldn't previously afford, which in turn creates demand for new jobs.

Thursday, March 31, 2016

I'm Speechless

Tuesday, March 15, 2016

Primitive Technology

This guy's videos are quite mesmerizing, and his descriptions are quite interesting to read.

Making Charcoal

Building a tiled roof hut


Sunday, March 6, 2016

When U.S. air force discovered the flaw of averages
He decided to find out. Using the size data he had gathered from 4,063 pilots, Daniels calculated the average of the 10 physical dimensions believed to be most relevant for design, including height, chest circumference and sleeve length. These formed the dimensions of the “average pilot,” which Daniels generously defined as someone whose measurements were within the middle 30 per cent of the range of values for each dimension. So, for example, even though the precise average height from the data was five foot nine, he defined the height of the “average pilot” as ranging from five-seven to five-11. Next, Daniels compared each individual pilot, one by one, to the average pilot. 
Before he crunched his numbers, the consensus among his fellow air force researchers was that the vast majority of pilots would be within the average range on most dimensions. After all, these pilots had already been pre-selected because they appeared to be average sized. (If you were, say, six foot seven, you would never have been recruited in the first place.) The scientists also expected that a sizable number of pilots would be within the average range on all 10 dimensions. But even Daniels was stunned when he tabulated the actual number.


Thursday, February 25, 2016

Sunday, February 21, 2016

The Secret Wizard of the Far Right
While you've likely never heard of him, chances are good you know his clients. Name a conservative firebrand and Elsass has likely been on his or her payroll. Ted Cruz, Rand Paul, Michele Bachmann, Newt Gingrich—he's worked with all of them, as well as a slew of Republican agitators who aren't yet household names but are doing everything in their power to change that. Elsass now counts more than 60 members of Congress on his client roster, many of whom belong to the rebellious Freedom Caucus that last fall hounded the Speaker of the House, John Boehner, into early retirement. This year, while most eyes are fixed on the presidential race, he's quietly obsessing over the Republicans' control of Congress, guiding the fortunes of 15 first-time candidates whom he hopes will join his small army already wreaking havoc in Washington.

Not surprisingly, Elsass's electoral success has made for a lucrative business, as the fleet of late-model Mercedes sitting outside his firm's headquarters attests. During the 2014 elections, the Strategy Group grossed more than $150 million—a figure that would be stunning even if the firm was located in the Beltway and not out among the mega-churches and big-box stores of exurban Columbus.

Tuesday, February 16, 2016

Kids, forget console gaming—play the FBI’s browser-based game instead
It basically looks like a prequel to the world's first-ever video game. The player uses the left- and right-arrow computer keys to move a running goat to avoid blocks. The blocks apparently represent violent extremists. Hit the block, and the goat explodes.

Saturday, February 6, 2016

Saturday, January 30, 2016

Why did crime plummet in the US?

I thought this was a very good compilation of the various proposed reasons for the huge drop in crime in the 90s, and some debate for and against each.

Friday, January 29, 2016

Listen to Wikipedia
Listen to the sound of Wikipedia's recent changes feed. Bells indicate additions and string plucks indicate subtractions. Pitch changes according to the size of the edit; the larger the edit, the deeper the note. Green circles show edits from unregistered contributors, and purple circles mark edits performed by automated bots. You may see announcements for new users as they join the site, punctuated by a string swell.

Sunday, January 10, 2016

Powerball Odds

So there is a lot of Powerball talk, and I am again intrigued by the possibility of a positive expected value for a lottery.  If you remember I wrote a post about Megamillions a few years ago, when the jackpot grew to $640 million.  The result, after taking into account both taxes and multiple winners, was that it still wasn't worth playing.  I decided to quickly do the same thing for this latest Powerball jackpot.

In a separate post, I made a model to predict the ticket sales based on jackpot amount.  This was quite a bit of work, so I'm not doing that here.  I'm just going to use the data for the latest drawing (Jan 9th, 2016) to see if that one drawing had a positive expected value in retrospect.

To begin, the expected value of the non jackpot prizes is $0.32, or about $0.28 if you include tax on the $50,000 and $1,000,000 prizes.  Note here, I'm ignoring the "Power Play" thing, which increases the payout for the nonjackpot prizes, but costs an extra $1.

Now we need to look at the jackpot.  The estimated upfront payout was $587,662,740.  After taxes that's $340,844,389.  The odds for Powerball recently got way harder, which is why this jackpot is so large.  This drawing had 440,321,172 tickets sold.  Doing the Poisson distribution we see the probability of various numbers of winners based on the odds and tickets sold:

0 22.1594%
1 33.3922%
2 25.1595%
3 12.6377%
4 4.7610%
5 1.4349%
6 0.3604%
7 0.0776%
8 0.0146%
9 0.0024%
10 0.0004%
11 0.0001%
12 0.0000%
13 0.0000%
14 0.0000%
15 0.0000%

The odds for no winners (which is what happened) was 22%.  This is due to the much lower odds of a jackpot in general.

Adding up the adjusted jackpot shares gives a total of $176,335,787.  This could be thought of as the true jackpot value after adjusting for taxes and the possibility of splitting the jackpot.  Multiplying by the odds of winning gives an expected value for the jackpot of $0.6035.  Adding the nonjackpot expected value gives a total Powerball expected value of $0.88.  The ticket costs $2, so it's not even half the value.

Some thoughts:  The odds were just increased in Oct 2015, and this is the first huge jackpot after that change.  More will follow, so it is possible that the expected value will improve as people get over the hype of a billion dollar jackpot.  However, it is worth noting that even if the jackpot doubled, and ticket sales remained constant the expected value would still be below the ticket price.

I haven't gone into details for the math here.  The calculations and commentaries are the same as the Megamillions post.  So please see that for more discussion.

Thursday, December 24, 2015

DAC and ADC explanation

This is a good video that explains how audio signals are sampled and represented digitally, and what effect that has on the final analog output.

Thursday, December 17, 2015

Armoured Octopus

Monday, December 14, 2015

Sunday, December 13, 2015

PBS Frontline: The Warning

PBS Frontline about the 2008 market crash.

Sunday, November 29, 2015

Life - Highly Intelligent Monkey

This documentary is on Netflix, and is quite good.

Saturday, October 17, 2015

Big Mac Index

The big mac index is a quick attempt at explaining purchasing power parity.  The idea being that simply knowing the exchange rate is not enough to know how valuable your money from one country will actually be when you try to purchase actual goods there.

Here is the fun part though:
Critics of the presidency of Cristina Fernández de Kirchner in Argentina and many economists believe that the government has for years falsified consumer price data to understate the country's true inflation rate. The Economist stated in January 2011 that Big Mac index "does support claims that Argentina’s government is cooking the books. The gap between its average annual rate of burger inflation (19%) and its official rate (10%) is far bigger than in any other country." That year the press began reporting on unusual behavior by the more than 200 Argentinean McDonald's restaurants. They no longer prominently advertised Big Macs for sale and the sandwich, both individually and as part of value meals, was being sold for an unusually low price compared to other items. Guillermo Moreno, Secretary of Commerce in the Kirchner government, reportedly forced McDonald's to sell the Big Mac at an artificially low price to manipulate the country's performance on the Big Mac index. In June 2012, the price of the Big Mac value meal suddenly rose by 26%, closer to that of other meals, after The Economist, The New York Times, and other media reported on the unusual pricing. A Buenos Aires newspaper stated "Moreno loses the battle".

Friday, October 16, 2015

How is NSA breaking so much crypto?
For the most common strength of Diffie-Hellman (1024 bits), it would cost a few hundred million dollars to build a machine, based on special purpose hardware, that would be able to crack one Diffie-Hellman prime every year.

Would this be worth it for an intelligence agency? Since a handful of primes are so widely reused, the payoff, in terms of connections they could decrypt, would be enormous. Breaking a single, common 1024-bit prime would allow NSA to passively decrypt connections to two-thirds of VPNs and a quarter of all SSH servers globally. Breaking a second 1024-bit prime would allow passive eavesdropping on connections to nearly 20% of the top million HTTPS websites. In other words, a one-time investment in massive computation would make it possible to eavesdrop on trillions of encrypted connections.

Friday, September 25, 2015

Volkswagen's Clean Diesel
Since 2009, we now know, Volkswagen had been inserting intricate code in its vehicle software that tracked steering and pedal movements. When those movements suggested that the car was being tested for nitrogen-oxide emissions in a lab, the car automatically turned its pollution controls on. The rest of the time, the pollution controls switched off.

This is old hat by now, but I thought this article did a good job of giving a bit more detail about the specifics of what actually happened.

Saturday, August 29, 2015

HTTP Status Cats API

Three years ago, I called out the proposed new TLDs as stupid. Today, I formally withdraw my oppositionIt turns out .cat is not one of the new TLDs so my opposition has been reinstated.

Monday, August 24, 2015

At the Institute for Marine Mammal Studies in Mississippi, Kelly the dolphin has built up quite a reputation. All the dolphins at the institute are trained to hold onto any litter that falls into their pools until they see a trainer, when they can trade the litter for fish. In this way, the dolphins help to keep their pools clean.

Kelly has taken this task one step further. When people drop paper into the water she hides it under a rock at the bottom of the pool. The next time a trainer passes, she goes down to the rock and tears off a piece of paper to give to the trainer. After a fish reward, she goes back down, tears off another piece of paper, gets another fish, and so on. This behaviour is interesting because it shows that Kelly has a sense of the future and delays gratification. She has realised that a big piece of paper gets the same reward as a small piece and so delivers only small pieces to keep the extra food coming. She has, in effect, trained the humans.

Her cunning has not stopped there. One day, when a gull flew into her pool, she grabbed it, waited for the trainers and then gave it to them. It was a large bird and so the trainers gave her lots of fish. This seemed to give Kelly a new idea. The next time she was fed, instead of eating the last fish, she took it to the bottom of the pool and hid it under the rock where she had been hiding the paper. When no trainers were present, she brought the fish to the surface and used it to lure the gulls, which she would catch to get even more fish. After mastering this lucrative strategy, she taught her calf, who taught other calves, and so gull-baiting has become a hot game among the dolphins.

Thursday, July 30, 2015

Crashes only on Wednesdays
Caught on yet?  On Wednesdays, and only on Wednesdays, if somebody manually twiddled certain bits in the monitor settings in a certain way, two events would occur during the same millisecond and caused the DB to throw an exception, and the error message that logged this would be exactly 81 bytes long including the null terminator, overflowing the 80-char buffer and causing the program to crash!

Friday, July 17, 2015

The View from the Front Seat of the Google Self-Driving Car
But we’re now driving enough — and getting hit enough — that we can start to make some assumptions about that real crashes-per-miles-driven rate; it’s looking higher than we thought. (Our cars, with safety drivers aboard, are now self-driving about 10,000 miles per week, which is about what a typical American adult drives in a year.) It’s particularly telling that we’re getting hit more often now that the majority of our driving is on surface streets rather than freeways; this is exactly where you’d expect a lot of minor, usually-unreported collisions to happen. Other drivers have hit us 14 times since the start of our project in 2009 (including 11 rear-enders), and not once has the self-driving car been the cause of the collision. Instead, the clear theme is human error and inattention. We’ll take all this as a signal that we’re starting to compare favorably with human drivers.

Wednesday, July 8, 2015

Concise electronics for geeks

This is a really good overview of analog electronics.

Wednesday, July 1, 2015

One dot per person for the entire US

This is a really good population map of the US, even ignoring that it has racial data too.

Tuesday, June 30, 2015

Randomness in Doom

Doom's source code is all online.  Someone posted a link to the RNG used, which is actually just returning a value from the same list of 256 numbers over and over in the same order:

unsigned char rndtable[256] = {
    0,   8, 109, 220, 222, 241, 149, 107,  75, 248, 254, 140,  16,  66 ,
    74,  21, 211,  47,  80, 242, 154,  27, 205, 128, 161,  89,  77,  36 ,
    95, 110,  85,  48, 212, 140, 211, 249,  22,  79, 200,  50,  28, 188 ,
    52, 140, 202, 120,  68, 145,  62,  70, 184, 190,  91, 197, 152, 224 ,
    149, 104,  25, 178, 252, 182, 202, 182, 141, 197,   4,  81, 181, 242 ,
    145,  42,  39, 227, 156, 198, 225, 193, 219,  93, 122, 175, 249,   0 ,
    175, 143,  70, 239,  46, 246, 163,  53, 163, 109, 168, 135,   2, 235 ,
    25,  92,  20, 145, 138,  77,  69, 166,  78, 176, 173, 212, 166, 113 ,
    94, 161,  41,  50, 239,  49, 111, 164,  70,  60,   2,  37, 171,  75 ,
    136, 156,  11,  56,  42, 146, 138, 229,  73, 146,  77,  61,  98, 196 ,
    135, 106,  63, 197, 195,  86,  96, 203, 113, 101, 170, 247, 181, 113 ,
    80, 250, 108,   7, 255, 237, 129, 226,  79, 107, 112, 166, 103, 241 ,
    24, 223, 239, 120, 198,  58,  60,  82, 128,   3, 184,  66, 143, 224 ,
    145, 224,  81, 206, 163,  45,  63,  90, 168, 114,  59,  33, 159,  95 ,
    28, 139, 123,  98, 125, 196,  15,  70, 194, 253,  54,  14, 109, 226 ,
    71,  17, 161,  93, 186,  87, 244, 138,  20,  52, 123, 251,  26,  36 ,
    17,  46,  52, 231, 232,  76,  31, 221,  84,  37, 216, 165, 212, 106 ,
    197, 242,  98,  43,  39, 175, 254, 145, 190,  84, 118, 222, 187, 136 ,
    120, 163, 236, 249

int rndindex = 0;
int prndindex = 0;

// Which one is deterministic?
int P_Random (void)
    prndindex = (prndindex+1)&0xff;
    return rndtable[prndindex];

int M_Random (void)
    rndindex = (rndindex+1)&0xff;
    return rndtable[rndindex];

void M_ClearRandom (void)
    rndindex = prndindex = 0;

There is an explanation of it here.  I find these kinds of hacks, used in 80s and 90s era games to save space and increase speed, interesting.

Here is a story of a guy that replaced all the values with the same number:
What does it play like? I tried two values, 0x00 and 0xFF. With either value, the screen "melt" effect that is used at the end of levels is replaced with a level vertical wipe: the randomness was used to offset each column. Monsters do not make different death noises at different times; only one is played for each category of monster. The bullet-based (hitscan) weapons have no spread at all: the shotgun becomes like a sniper rifle, and the chain-gun is likewise always true. You'd think this would make the super-shotgun a pretty lethal weapon, but it seems to have been nerfed: the spread pattern is integral to its function.

With 0x00, monsters never make their idle noises (breathing etc.) On the other hand, with 0xFF, they always do: so often, that each sample collides with the previous one, and you just get a sort-of monster drone. This is quite overwhelming with even a small pack of monsters.

Tuesday, June 16, 2015

Civilization 4 on Linux Via Wine

I have a week off, and figured I'd be productive by playing Civ continuously the entire time.  I've used Wine a bit, but not much with modern games like Civ 4.  It took me several hours, so I figured I'd document the process here for future reference.

To begin, get iso's of the game and two expansions.  Wine doesn't work well with multidisc installations, but if you have isos you can mount them all before you begin.  Also each disc is one independent installation.  I have the actual discs, but found it much easier to download them.

It is also easier to use Wine as 32 bit, instead of trying to get 64 bit to work.  Since I wasn't using Wine for anything important, I just deleted my ~/.wine directory.  I then ran export WINEARCH=win32 before I ran any wine command.  Export will save that variable in your terminal window until you close it, but with multiple terminals open I found it safer to just compulsively enter it.

Next, you'll need a shell script called Winetricks.  You run Winetricks with arguments of various dlls and other things you need to be manually overridden.  For Civ 4 you'll need msxml3 for sure.  I ran winetricks msxml3 msxml4 vcrun2003 quartz devenum corefonts lucida tahoma, because I found it somewhere on the internet.

Run winecfg and go to the Libraries tab.  Find the library called gameux, and add it to the list of overrides, and then edit it to be disabled.  I also found that Wine did not do a good job of guessing my graphics RAM, so I had to run wine regedit.exe and add the key HKCU>Software>Wine>Direct3D>VideoMemorySize and set the value to 512.

Now, mount your 3 isos.  Navigate to the directory containing the installs and run them via Wine (make sure you've exported WINEARCH=win32 first).  The installs were straightforward.  After you've installed Beyond the Sword, download the latest patch (3.19) and install that via Wine.  The expansions will install the patches for the vanilla game, and the latest patch makes it no-cd so no need to download cracks.

You can navigate to ~/.wine/drive_c/.  If you see "Program Files (x86)" it means you messed up with your export WINEARCH=win32's and installed the game as 64 bit.  It may still work, but if not delete ~/.wine and try again.

The game is at: "~/.wine/drive_c/Program Files/Firaxis Games/Sid Meier's Civilization 4/Beyond the Sword/Civ4BeyondSword.exe".  Run it via Wine.  After it starts, you can exit and then find the config file at "~/My Games/Beyond the Sword/CivilizationIV.ini".  If you are having trouble you can set FullScreen = 0 and find ScreenHeight and ScreenWidth and set them low.  I have no trouble with full screen 1920x1080 though.  Set NoIntroMovie = 1, AutoSaveInterval = 1, DisableFileCaching = 1, DisableCaching = 1, ModularLoading = 1.

After that you should be good.  The game runs quite well, I've only noticed some slight graphics errors on some of the 3d animated leaders' faces.  I did have crashing sometimes when attempting to open certain advisor windows (military advisor seemed most common).  The Windows error message recommended I lower graphics settings and so I did from high to medium and haven't had a crash since.

Wednesday, June 10, 2015

The Making of Lemmings

Mike Dailly had seen tiny 5-pixel high sprites in games like Oids, a popular Atari ST shooter where the player’s ship rescued little android slaves, and thought that somewhere between this and a 16×16 sprite would be a sweet spot – where the small size made the Walker look big by comparison, but the animations were still good enough to impart character. One lunchtime he made an image of little men being crushed by weights, and shot by a laser gun – everyone loved it, and Gary Timmons added a few more traps. While everyone was laughing, Russell Kay was the first to say ‘There’s a game in that!’

Friday, June 5, 2015

How Tesla Will Change The World

I asked him what it was like to come to Tesla after having spent years at more established car companies. He described the difference like this: “A company like GM is a finance-driven company who always has to live up to financial expectations. Here we look at it the other way around—the product is successful when it’s great, and the company becomes great because of that.” (This mirrored what Musk had told me earlier in the day: “The moment the person leading a company thinks numbers have value in themselves, the company’s done. The moment the CFO becomes CEO—it’s done. Game over.”) Von Holzhausen went on, saying, “Another difference is that at other companies, engineering comes first—a design package is prescribed on the designer and they’re told to make it beautiful. At Tesla, design and engineering are assigned equal value, and Elon keeps them opposed to each other.” Now that von Holzhausen has gotten used to his freedom to be obsessed with the product at Tesla, he says he “would dread to go back to pre-historic ways.”

Monday, April 20, 2015

Pizza Calculator

A while ago made a table of the common pizza sizes so that we could better compare pizzas.  The problem with that was that it was difficult to compare deals of multiple pizzas of different sizes.

I made a quick javascript calculator that lets you enter the number of pizzas, the size, and the total price and then tell you what the price per standard pie or slice is.

I expect this to be quite popular at parties, as all good parties have the phrase "just go to my github page" at some point.

Sunday, April 19, 2015

The Star Wars Saga: Introducing Machete Order
Next time you want to introduce someone to Star Wars for the first time, watch the films with them in this order: IV, V, II, III, VI

As I mentioned, this creates a lot of tension after the cliffhanger ending of Episode V. It also uses the original trilogy as a framing device for the prequel trilogy. Vader drops this huge bomb that he's Luke's father, then we spend two movies proving he's telling the truth, then we see how it gets resolved. The Star Wars watching experience gets to start with the film that does the best job of establishing the Star Wars universe, Episode IV, and it ends with the most satisfying ending, Episode VI. It also starts the series off with the two strongest films, and allows you to never have to either start or end your viewing experience with a shitty movie. Two films of Luke's story, two films of Anakin's story, then a single film that intertwines and ends both stories.

Tuesday, April 7, 2015

The Theory of Interstellar Trade

This paper extends interplanetary trade theory to an interstellar setting. It is chiefly concerned with the following question: how should interest charges on goods in transit be computed when the goods travel at close to the speed of light? This is a problem because the time taken in transit will appear less to an observer traveling with the goods than to a stationary observer. A solution is derived from economic theory, and two useless but true theorems are proved.