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Ask Slashdot: How Reproducible Is Arithmetic In the Cloud?

daniel_mcl You need to know some numerical analysis (226 comments)

If your calculations are processor-dependent, that's a bad sign for your code. If your results really depend on things that can be altered by the specific floating-point implementation, you need to write code that's robust to changes in the way floating-point arithmetic is done, generally by tracking the uncertainty associated with each number in your calculation. (Obviously you don't need real-time performance since you're using cloud computing in the first place.) I'm not an expert on Mathematica, but it probably has such things built in if you go through the documentation, since Mathematica notebooks are supposed to exhibit reproduceable behavior on different machines. (Which is not to say that no matter what you write it's automatically going to be reproduceable.

Archiving hardware to get consistent results is mainly used when there are legal issues and some lawyer can jump in and say, "A-ha! This bit here is different, and therefore there's some kind of fraud going on!"

about 10 months ago

French Police Unsure Which Twin To Charge In Sexual Assaults

daniel_mcl Re:!(Prisoner's Dilemma) (626 comments)

Yep. Generally what happens when there are multiple defendants and no solid case is that the suspects are threatened with a Russian Roulette-style court case, causing one to decide to confess and implicate the other defendants in exchange for a lighter penalty.

about a year and a half ago

UC's For-Pay Online Course Draws 4 Non-UC Students

daniel_mcl Re:$1400-$2400 per course? (177 comments)

I dunno what you mean by "UC isn't even all that prestigious," but the Times Higher Education Supplement rated UC Berkeley as the #8 university in the world and #6 in the U.S., behind Caltech, Stanford, Harvard, MIT, and Princeton. In particular, they feel that it's better than the entire university system of every country that isn't the U.S. or the U.K. I'd say that's pretty good. UCLA is world-class as well, and UCSF is one of the top three or four medical schools in the world. Even the lesser-known campuses like Riverside and Irvine have strong reputations.

about a year and a half ago

How Does a Single Line of BASIC Make an Intricate Maze?

daniel_mcl Re:Without the use of a loop!? (438 comments)

Personally, I find it fascinating that if you just randomly put forward and back slashes on a screen then it forms a pattern like that. To me, it's much more interesting than an algorithm that generates mazes. I'd have expected that you just got a bunch of diamonds and things.

about 2 years ago

Ask Slashdot: What Were You Taught About Computers In High School?

daniel_mcl I'm in my late 20's now (632 comments)

In elementary school in the late 1980's, our school librarian of all people -- a nice, fun older lady -- taught us LOGO programming. The class went relatively deep given that the students were all eight or nine years old. Our last assignment was to write a function that would draw a regular n-gon (taking n as a parameter), then incorporate that into a recursive function that would draw arbitrarily deep spirograph-type shapes using a callback function. Pretty much everyone figured it out on his or her own, as I recall. Our "computer lab" at the time consisted of someone going and setting up folding tables in a hallway or the cafeteria and then lugging a bunch of Apple //e machines out of a closet, then tearing the whole setup down after a couple of hours.

In middle school, we had a short unit on BASIC programming, by now on the Apple IIGS. By this time it was the late 1990's, and I'd started teaching myself QBASIC on our home PC; the computers we were using in school were around seven years old by this point.

In high school, I took a semester of computer science as a freshman and a year of "AP Computer Science" as a sophomore. This was largely just indoctrination into OOP. The entire course consisted of writing completely trivial C++ programs which would consist of several objects, none of whose member functions exceeded one or two lines. Nobody really enjoyed the course or learned much of anything, but we were pretty much bound to the AP curriculum so there wasn't much that could be done.

Had I my druthers, I'd design a computer science program for schoolkids by focusing more on the sort of stuff I did as a little kid, which was really conceptually much deeper and certainly a lot more fun.

about 2 years ago

Ask Slashdot: What To Do With a Math Degree?

daniel_mcl Re:NSA (416 comments)

You *definitely* don't need a PhD to work as a mathematician at the NSA, nor do you need a specific background in cryptography. If you failed abstract algebra in college you're probably not getting a job there, but my understanding is that it's not that difficult to get in so long as you're qualified, a citizen, and can pass a background check. The NSA is the single largest employer of mathematicians in the world -- they're certainly not just hiring the extreme elites.

more than 2 years ago

Twitter Bomb Joke Case Rolls Back Into UK Courts

daniel_mcl Re:Even free speech has its limit (174 comments)

Did you read his twitter post? It was an obvious joke. No reasonable person could possibly interpret it as an actual threat. Most unreasonable people would even understand it was a joke.

more than 2 years ago

Icons That Don't Make Sense Anymore

daniel_mcl Re:Let's see now... (713 comments)

I'm pretty sure most young people have also seen calendars, clipboards, film cameras, and Manila folders outside of a museum.

more than 2 years ago

University of Florida Eliminates Computer Science Department

daniel_mcl Re:The Department of Redundancy Department (628 comments)

Unless things have drastically changed since (recently) I went to Caltech, math is its own department -- part of the division of physics, math, and astronomy -- and CS is its own department as well -- part of the division of engineering and applied sciences. There's also an applied/computational math under the E&AS umbrella, but that's not anything like either math or CS.

more than 2 years ago

Are You Better At Math Than a 4th (or 10th) Grader?

daniel_mcl Re:What this means (845 comments)

Generally coursework is the least important component of a graduate education -- in some cases, people won't take any courses at all during certain terms. Additionally, the courses generally require much more work, and a 'C' is a failing grade.

more than 2 years ago

Do Spoilers Ruin a Good Story? No, Say Researchers

daniel_mcl I don't care how the average person enjoys a story (238 comments)

This study tries to figure out in what way the average person enjoys a story. Aside from the fact that asking people to rate things from 1 to 10 is a great way to determine their favorite numbers and very little else, even if the study were completely accurate I wouldn't care. Why? Because the average person is the guy who makes Michael Bay, Twilight, The Jersey Shore, and Justin Bieber popular. They are the people who books like "The Secret" outsell actual literature. It's already well-established that the average person is worse than useless, dragging us into the gutter and away from the stars. If this research could start to teach us to fix what's wrong with the average person then maybe it'd be worthwhile, but it's clear from the researchers' comments that they actually think that there's something *okay* about the fact that people have gotten so stupid that they can't even follow a simple plot without having the Cliff's Notes embedded into the first paragraph.

more than 3 years ago

Could You Pass Harvard's Entrance Exam From 1869?

daniel_mcl Re:Educational standards (741 comments)

If your idea is that the average person alive today -- never mind the average high school student -- has any knowledge at all of relativistic mechanics, evolutionary biology, computer science/engineering, medical science, etc., I think you'll find you're sadly mistaken. Yes, the average teenager knows how to use a cell phone. Clearly this is an insurmountable obstacle, and Isaac Newton himself would be unable to figure out my Nokia.

At any rate, the material on the "arithmetic" and "algebra" sections is still taught and used in schools today, and I'll outright guarantee you that if I printed those out and took them to a Calculus III section at the local university I'd be unlikely to get a very high pass rate, despite the fact that most of them have memorized how to take dozens of integrals or apply Lagrange multipliers.

Knowledge isn't worth as much as people seem to think; at its heart, it's just trivia. What matters is the ability to think, and that doesn't change from generation to generation.

more than 3 years ago

Could You Pass Harvard's Entrance Exam From 1869?

daniel_mcl Re:different time (741 comments)

Please tell me you're kidding. Latin != Italian.

And for that matter, heaven forbid that college should be about getting an education instead of necessary vocational training. Clearly knowledge is worthless except as a bullet on a résumé.

more than 3 years ago

Google Engineer Decries Complexity of Java, C++

daniel_mcl Re:C too complex? Hilarious. (878 comments)

Umm, you realize this is *Rob Pike* you're talking about, right? One of the original developers of UNIX? I'm guessing that, what with working at Bell Labs while they were *inventing* C, he might know a little more about the language than you do.

more than 4 years ago

New "Circuit Breaker" Imposed To Stop Market Crash

daniel_mcl Re:Good Fix... (460 comments)

'Your stocks will be worthless (than any other's) in 23 hours if and only if those said others are allowed to sell sooner than you and *specially* sooner than the buyer's knowledge about the bankrupcy'

No, your stocks will be worthless, period. People won't magically be willing to pay more money for stock in a bankrupt company because they weren't allowed to trade the stock for a while. But this isn't really a great example of why liquidity is necessary, because in this case there's not much that can be done. Market liquidity is necessary to allow risks to be reallocated, and risks need to be reallocated on a regular basis, not just once a day. Just because you could conceivably regulate "official" stock prices doesn't mean you can regulate the instantaneous factors that dictate them -- the cost of oil, local and international politics, the weather, etc.

more than 4 years ago

New "Circuit Breaker" Imposed To Stop Market Crash

daniel_mcl Re:Good Fix... (460 comments)

"Remember that extracting wealth from the markets and transferring it from one account to another is not the same thing as 'profit', because it reduces the wealth available to actual productive investment - the corporate processes which do not and cannot change any faster than the time it takes to gear-up a factory or harvest a crop."

Nonsense. Say the price of oil changes; then all of a sudden all sorts of companies make or lose enormous amounts of money. Same thing with interest rates, the weather, natural disasters, international politics, etc. Here's an exercise for you: go buy stock in a pharmaceutical company that's waiting to get approval of a new drug. On principal, refuse to trade it even after the announcement comes out and the price spikes or plunges. Afterwards, you can give us all a nice lecture on how little you care for market liquidity.

For that matter, how do you determine a fair price to pay for your investments? Do you bring up a spreadsheet, model the company's discounted future earnings, and derive the price you're willing to buy and sell at? Of course not. You rely on the market to let you know what a fair price is. Without a liquid market, you might as well be buying stock from some guy who calls you up on the phone.

Of course, I'm going to guess that you or someone else is going to say, "But I just take the high road -- I invest in indexed mutual funds and don't try to beat the market." But what do you think the fund's traders are doing? Just sitting around all day and not trading? All you're doing is paying someone else to execute those same trades for you.

more than 4 years ago

The Chinese Route To a Web Free of Porn

daniel_mcl Re:Your sig (420 comments)

And you didn't even notice that it begins "For all intensive purposes..."

more than 4 years ago



Worldwide celebrations as time reaches 1234567890

daniel_mcl daniel_mcl writes  |  more than 5 years ago

daniel_mcl (77919) writes "It's time to party like it's 1234567890 — 'cause it is! On this Friday, Feb 13 at exactly 3:31:30 PM (PST), Unix time will equal '1234567890'. Check the list at to find out where your local party is, or put this handy counter up on the bigscreen and count down the seconds in your living room or office with someone special (or at least especially nerdy)! As of the time of this writing there are just under four hours to go, so hurry up and make your plans because this is only gonna happen once!"
Link to Original Source


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