skysight-inc/HackerNews huggingface dataset:
Professor John Stillwell writes, in the preface to his book Numbers and Geometry (New York: Springer-Verlag, 1998):

"What should every aspiring mathematician know? The answer for most of the 20th century has been: calculus. . . . Mathematics today is . . . much more than calculus; and the calculus now taught is, sadly, much less than it used to be. Little by little, calculus has been deprived of the algebra, geometry, and logic it needs to sustain it, until many institutions have had to put it on high-tech life-support systems. A subject struggling to survive is hardly a good introduction to the vigor of real mathematics.

". . . . In the current situation, we need to revive not only calculus, but also algebra, geometry, and the whole idea that mathematics is a rigorous, cumulative discipline in which each mathematician stands on the shoulders of giants.

"The best way to teach real mathematics, I believe, is to start deeper down, with the elementary ideas of number and space. Everyone concedes that these are fundamental, but they have been scandalously neglected, perhaps in the naive belief that anyone learning calculus has outgrown them. In fact, arithmetic, algebra, and geometry can never be outgrown, and the most rewarding path to higher mathematics sustains their development alongside the 'advanced' branches such as calculus. Also, by maintaining ties between these disciplines, it is possible to present a more unified view of mathematics, yet at the same time to include more spice and variety."

Stillwell demonstrates what he means about the interconnectedness and depth of "elementary" topics in the rest of his book, which is a delight to read and full of thought-provoking problems.

http://www.amazon.com/gp/product/0387982892/
I promise to take care of toxic waste for some large
manufacturing corporations. I take their money and 'dispose'
of the waste. What if I dispose of the waste into waterways
(lakes, rivers,etc)? My customers are happy because the waste
is taken off of their hands. If anyone ever finds out about
the dumping, they can claim to no know anything (and they
may well not know anything) and *I'm* the one that takes
the fall, not them. In the meantime, they get to reap the
benefits of cheaper disposal (since it's not being disposed
of properly). I would hardly say that I'm making the world
a better place though.

"happy customers" != "a better world"
Of all the industries being ravished by web technologies, I would argue that the recording companies certainly brought this downfall upon themselves more than any other. There are problems with this new landscape though. To quote from my executive summary:

"Advancements in technology have drastically changed the music industry by providing musicians direct access to resources previously controlled by record labels. While the Internet has increased musicians’ artistic freedom, it has also given them unwanted responsibility over their day-to-day operations. Musicians have to book and promote their own shows while also coordinating distribution channels for selling goods. This do- it-yourself environment has forced independent artists to divert their attention away from making music."
WPA Cracker - $17 cloud-based WPA cracking service
Do you have any sources for that information?
Yeah but to me the quality of any manufacturer then Apple falls short. I've owned Windows Mobile, Andriod (HTC Hero) and now iPhone. iPhone for me is superior.

Google i think needs to make their own device to match the quality/stability of the iPhone!
Becoming an expert has far more to do with knowing how to get things done in a known time frame than knowing every little piece of triva. One you code in the same language with 3 or 4 compilers you start to look at edge cases as a dangerous no mans land to be avoided if at all possible.

PS: I worked with code from the 1984 Macintosh days that was still in use in 2005. You could see where people had updated from Motorola 68020 to PPC and if it had not been stripped out some poor coder might have updated the remaining ASM to x86.
You can already get a tablet that does that. I never understand these kinds of comments.

"I wouldn't buy that. Why didn't they make it into a completely different kind of product." It's like looking at a motorbike & saying "They should have given it four wheels & aircon."
This duality shows up in fluid simulation as well: http://en.wikipedia.org/wiki/Lagrangian_and_Eulerian_specifi...
Ask HN: are you a freelance rails developer?
Greetings,

My partner and I recently launched an iPhone app with ambitious plans to turn it into a platform. Next step in that process is to port it to the web. I'm looking for a good rails developer that knows their way around mysql. The app and all app logic rests on our servers, not the client side iPhone app.

We are based in NYC. If you are that's a plus. Our app is an iPhone app, so if you have one that is a plus. We are a boot strapped startup but we pay for all our services so we aren't looking for an equity arrangement here but arent going to pay $80 am hour either. If you're either a noob or uber pro, we are probably not for you.

I usually check searchyc.com before posting stuff like this and didn't see anything that helped. Therefore please submit your info as a comment and I'll get in touch with you, that way others can benefit from this post down the rd.

Company: Groupie www.groupie.mobi
App: Groupie
Video walkthrough: www.groupie.mobi/whatisgroupie
My name: Leo
Contact: leo@groupie.mobi
Or don’t have as many people watching, and can afford the bandwidth?
About the Batik library: What makes you think that it is the JVMs fault that it uses that much memory? It seems much more likely that it is a just a crappy library with lots of memory leaks.
myTouches should be on 1.6 already. T-Mobile was pushing the update in October (November?).
Hack or scam?  Two arrested in Japan for exploiting travel reward points.
bingo!

thanks for that - i've been racking my head trying to think where in santiago i could buy a bagel tomorrow. now i have no need :o)
Significant missing detail: there seems to have been disagreement on the pricing, with Arrington presumably wanting a lower margin product that was closer to his original vision. This seems to be the thing that Fusion Garage's investors balked at.
Stepping through malloc isn't going to help you much in this case. But most people I've met that have written a lot of C/C++ code have seen this bug at least once.

When you start asking about how much memory malloc is asking for, that's a tip-off in the wrong direction for me too; malloc handles "out of memory" pretty gracefully.
They're franchising now, and Pinkberry is looking for more area developers. It's a fad, sure, but in the right locations anything is possible.

Back in the time of this article (2006) I'm not sure they were, I did contact them once about it and the rather confused reply I got back said they weren't franchising and implied being corporately owned.
You would then be buried under an avalanche of log lines, but then I'd just ask "what are you looking for?".
On a side note: Long passwords are generally a good idea.

On websites that support it you can just type in a memorable phrase, with spaces and everything, and it will be more secure than the usual 10 char alphabet soup.

A password I commonly use is:

Length limits on password input fields suck donkey balls.
Would you say that since no other program actually competes with yours - you get your pick of the best applicants - YC probably benefits the more clones there are?
Thanks for the (verbose... kidding!) explanation.

Mine:

Not verbose:

puts "Hello, world"

verbose:

public class Hello {
public static void main(String[] args) {
System.out.println("Hello, world!");
}
}
Site that helped MIT team win DARPA Challenge
They have reoccurring revenue - this does not.
He's addressing the fear of 'stealing my great idea!' and stealing slides and starting a company based on them certainly qualifies.
> persistent storage: everyone has this - even Amazon now with their EBS which is way more flexible.

The point is that theirs is persistent by default. You're given a (probably sparse) filesystem on top of RAID 1+0. You can reboot the machine (or something can fail) and your data is still there. With this and static IPs you basically don't have to think about it as a special "cloud" machine and plan for failures and data loss.

With Amazon EBS you pay per operation and it's a slower networked disk. If a node fails you need to bring up another and mount/configure the EBS volumes to get up and moving again.

Use the right tool for the right job, of course, but for my time & money I like Rackspace's persistent storage more.
Trusting Google’s Algorithms to Explain Google’s Algorithms
It also invokes the dtors for the object, and, more importantly, does all this before the caller method returns, so that when "delete this" finishes, the program still has to execute code in the method context of a dead object --- which usually works.
It looks like FusionGarage was looking at initial funding (or acquisition) from techcrunch early in product development cycle. And techcrunch (i believe intentionally) avoided commiting anything earlier itself since they thought it as too risky. Techcrunch thought that they would bring in world class investors and team later around the product development ( few months before launch) and get a good stake in the product for that. And FusionGarage investors were frustrated that TC can come around later (when the risk is too low) and take a major bite of it.

In between, TC claims that they did initial marketing for the product. Technically it may be correct. But From risk factor, what was at stake here for TC ? Actually TC biz model works on buzz factor. More Buzz equals more readers and Revenue. So at worst (if product fails), they made some money out of the whole buzz. But for FusionGarage (and their investors), everything was at stake.

Arrington might be correct, they could have negotiated on the product stake. ( How about : 2% for initial idea discussion, 2% for initial marketing, and 2% bring in new investors and team .) I guess such a 5-6% offer would have still led to such a breakup. (But can u give a 30% stake just for blogging about a product ?)

To me, Arrington is a Bad (Scary) Startup-Investor here (keeping the startup in guessing game till end ..), and FusionGarage has a bad CEO who could not anticipate what was to come. And those investors are smart to bring the whole stuff out before the product is actually launched.
I always find it curious when the number of comments on an article exceed that of the point value. It leads me to suspect that users get angry over the article for some reason.

To add to the discussion, however, I knew the answer because I had a run in with doing this sort of thing. I had built a simple game with OpenGL - stuff moved around on the screen and you could shoot it. Due to the way I constructed the objects, it was trivial to "Delete this" when the object should disappear - a bullet collides with an enemy, perhaps. I did it, it worked exactly as expected.

The follow up question - "What can you do after delete this; ?" - also reared it's head, and that's when I found the other edge to the sword and shied away from it's usage.

It felt so much more elegant as "delete this;" :(
The question is not whether or not the language spec permits you to do this. The question is about what happens if you do.
The function's body is not part of the object itself. When you delete the object, you can keep executing the function just fine, as long as you don't access any member variables.
Ask HN:  Review my Startup, Online Classified
A few months ago I got fed up with the general state of online classified sites. They suck. They really suck.

I started YourGrounds.com as a way to remedy this travesty. Yourgrounds takes the ambiguity out of searching, and you no longer have to spend hours searching through postings.

Here's what we did - you can create a wishlist that searches even when you aren't on the site - if the site matches what you're looking for to something someones posts, it will notify you.

Simply put, I want you guys to tell me what you think.

Use the code: hackernews during your registration, there are 100 slots open right now.

There's still work to be done, and I want to know how I can make this the best possible site for everybody.

Enjoy!

If you have personal thoughts, questions or comments, you can direct them to brendan@yourgrounds.com
The Desperation Economy
The fact that the comments are often better than the articles they attach to is the thing a lot of us like about HN.
> of course, efficiently searching thru a corpus of millions of faces

There was research cited here a while ago on the high accuracy obtained by constraining the search space to within one's social graph (hundreds vs millions). While it might not identify the stranger at the bar, it might identify their companions and so on. Six degrees of separation in real-time.
I'm a freelance Rails dev in NYC, with plenty of experience, but my rates are higher than you are looking for. I recommend emailing the ruby-nyc mailing list, good place to find Rails Devs - http://nycruby.org/wiki/
Run the program under valgrind.
Yeah, sharing objects on the thread-local stack is definitely a bad idea.

But as long as the alloca'd memory is only accessed from within the same thread, it is -- AFAIK -- safe to call alloca() simultaneously from multiple threads, the same as malloc(). I think that qualifies as thread-safety by the usual definition: i.e. the function doesn't access statics or globals.

(Of course this will vary depending on the CRT. I don't think any UNIXes nowadays ship without threading support in the CRT, but Microsoft Visual C++ used to have separate thread-safe and non-thread-safe C libraries.)
> Length limits on password input fields suck donkey balls

At one point I was using MD5 hashes for passwords, but I kept running into password limits so I had to stop.
It's been years since I worked with C++, but my recollection is that C++ programming involved a lot of memorization of edge cases just as a guard against running into them.
This site is full of "stealth" camper stories like that. Pretty creative people and some fascinating reading.

http://cheaprvliving.com/
X-hacker: the result of curl --head wordpress.com
$ curl --head wordpress.com
HTTP/1.1 200 OK
Server: nginx
Date: Tue, 08 Dec 2009 00:08:45 GMT
Content-Type: text/html; charset=UTF-8
Connection: close
Last-Modified: Tue, 08 Dec 2009 00:08:25 +0000
Cache-Control: max-age=10, must-revalidate
Vary: Cookie
X-hacker: If you're reading this, you should visit automattic.com/jobs
and apply to join the fun, mention this header.
X-Pingback: http://wordpress.com/xmlrpc.php
Link: <http://wp.me/1>; rel=shortlink
X-nananana: Batcache
C and C++ for starters.
Pure-JDBC SQL command line with tab expansion & readline goodies
I beg to differ:

http://www.armada-online.com/
IMO, that's not a bad question. C++ is not my thing, but I don't see anyone mentioning.

A) Running the code on another system to double check that the systems memory / OS has not been corrupted. I once wasted ~6 hours on a corrupted production box, so now the new rule is when system call fail double check it's not just the machine.

B) Double check that none of the memory allocation / book keeping memory had been over written, memory had not been freed twice etc.

Honestly, I usually try to do that type of stuff by direct code inspection. If it's failed once I am probably going to need to debug related code in the not to distant future so really understanding what's going on is important, but hack and slash debugging can be fun.
I used to use svn, but these days I use git for maintaining static websites.

Maybe I missed something in this article, but the key to static websites (as far as I see it) is using a templating system. Put your templates, content and configuration under version control and you're pretty much done. The website itself is a generated artifact.
Hmmm...interesting, but it seems like this takes automation a bit far. I also use Git as a single developer on a project of mine, and I have staging and production environments on my server, but I have simple deployment scripts that I run to update the changes on the server, clear any cache files, etc. It's not that much more complicated than what he does here, but it gives me the peace of mind of knowing that I can commit my changes without the world seeing them automatically.
Sacrifice Your Health For Your Startup
People have diverse complaints about Craigslist, although it's free and in general, it works.

My complaint with CL is it's not open enough. I truly wish Craig would drink the Jack Dorsey kool-aid, and have an open API for CL allowing independent developers to innovate around it.

Having said all that... your site is even more closed than CL. I understand private betas, but it's a classifieds site, and you're competing with CL, and the message is: even if I logged in and created an ad, no one would see it.

you no longer have to spend hours searching through postings.

That is admirable, and I hope it succeeds. But the problem right now with online classifieds is centered around whether distributed innovation is possible. I'd love to place an ad in a way that doesn't result in one company controlling it exclusively.
definitely. I mean both HP and Apple have engineers, but I could never figure out what makes Apple better - please explain? Since the argument is that it is all engineers and 'lines of code', that means that it comes down to who writes the code, right? Which explains why Apple is so great, or maybe not.

The sooner you wake up to what marketing really is the better
> but have difficulty really coming up with uses

Uses would be more about being a tourist and getting a feel for where you are than mens/womens toilets - as you say, you can memorise those fairly quickly.

More like, standing in a subway, there's a poster, it says something about the train something ... wonder what? Walking past a big lake, there's a sign about some project that involves a pipe low down and a pipe further up, but what is it doing - taking thermal energy or using the water as coolant? Walking through the city streets, there's a plaque on the side of a building - something something 1872 something national? people? something something Joan 1st. Eh? What's on these fliers that are being handed out? What are the menu descriptions?

The easier it is to do, the more likely you are to do it - it's only important things that you would fish out a dictionary and start deciphering, this would be for everything and anything which attracts your interest.

Good point about the data roaming, though.
What happens to purchases already made? Would your iphone still have the app or will it disappear?
CHEATER!
The tool is quite old still it's delightful to use when you must do something in SQL, esp. on multiple sessions.

Cool feature is that it has database dump command which outputs data sexps.
Engadget wouldnt have been doing a "Press Conference Live Blog" if it weren't for the TechCrunch scandal.
Apple should automatically flag accounts who release over a dozen, fifty, or so many apps and review each account. This would cut down on abusers and let them focus their efforts more productively.
One upvote for using the word scapegoat correctly, six downvotes for cluttering the thread.

Also, if you're going to ask a chatty question, it's distasteful to say "I'll go first", especially when you are doing so in the body of the question.
http://www.schneierfacts.com/fact/27
adam sandler?
Previous work in the domain by others:

Nokia: http://digital.venturebeat.com/2008/04/11/nokia-develops-nav... (they use the golden gate as their example too)
Also: http://www.mobvis.org/publications/MMT2007_Paletta.pdf, http://mirw09.offis.de/paper/What%20is%20That%20-%20Object%2...

'World browser': http://www.wikitude.org/

Using GPS together with the compass to get interesting results:
2006, Japan: http://www.nytimes.com/2006/06/28/technology/28locate.html and now there are iPhone applications
http://www.youtube.com/watch?v=U2uH-jrsSxs&feature=playe...
When I was interviewing C++ programmers, we had a C++ test, and some stock questions I asked face to face.

However, I found I could pretty much weed the good C++ programmers from the mediocre/just read about C++ before the interview by asking one question:

"What is a virtual function?"

If they have trouble starting to answer it, give them a hint with "What would cause you to type the keyword 'virtual' in your code?"

You would be amazed how many C++ coders don't really know the answer to this, or what is going on (vtables etc, or even just the behaviour).

One candidate answered "I'd make a function virtual if there were any other virtual functions in the class." It seems like there is no shortage of bad answers to this question. All the people who ever gave me a correct answer (hit rate was <10% of candidates) were good C++ developers.

It's a good question :-).
It has been about one year since I last heard any talk of raytracing, so that sounds about right. I'm glad they're not wasting time on that!
Barnes & Noble Nook Review: Pretty Damn Good
More photos on Virgin’s site:

http://www.virgin.com/travel/inside-virgin-travel/virgin-gal...
You keep executing the function because it's on the stack. The program counter keeps moving through the method until it hits a return statement. God help you if you try to reference one of the class' internal data objects as their heap space could have been allocated to something else running on another thread.
TCP vs UDP is a hot debate. It really depends on the type of game you're trying to build.

http://www.gamedev.net/community/forums/topic.asp?topic_id=3...

As an interesting note, World of Warcraft uses TCP.
This looks like something that could potentially reinvigorate the classified space.

I, for one, am all for it.
I guess I just don't understand wtf the point of this thing is when the Archos 9 is on sale for $499
Documents -> People -> Places -> Objects. What's next?

You should check out FluidDB from the FluidInfo guys... http://fluidinfo.com/
I've always loved the proof of the Gauss-Bonnet theorem, which ties together differential geometry and topology, and basically states that however you distort a compact, boundaryless two-dimensional Riemannian manifold, its total curvature remains the same. The proof (well, the proof I learned -- there are several) was long with many steps, each of which was simple and intuitive. It comes together in a sort of crescendo. Here: http://www.math.dartmouth.edu/~leibon/gbt/sld001.htm
No. The ssid is used as part of the encryption. Changing it to something very obscure invalidates any precomputed tables and forces a brute force attack
In the end, it is the court's opinion on the legality of their actions that matters, not how the case came before it.
There's been some academic work on identifying these attacks recently. Most of the work I've seen crawls social networks directly. You could try contacting the authors to see if they will share their data sets.

Representative example:
SybilLimit: A Near-Optimal Social Network Defense against Sybil Attacks
Haifeng Yu, Phillip B. Gibbons, Michael Kaminsky,Feng Xiao
http://www.comp.nus.edu.sg/~yuhf/yuh-sybillimit.pdf

A more recent paper looks at a data set from Digg to discover vote manipulation; the authors are interested in further applications and would probably appreciate your contact.

Sybil Resilient Content Rating
D.M. Tran, B. Min, J. Li, L. Subramanian
http://www.cs.nyu.edu/~lakshmi/nsdi09.pdf
They stay on your iPhone/iPod. But of course you no longer can get updates.

I have the Delicious Library app that the developer pulled due to it violating Amazon's API ToS (as revised after the app was released). It still works, and has even made a device transition (iPod -> iPhone).
Yet another otherwise-insightful essay on ChromeOS that completely ignores the existence of Google Native Client -- rich native applications that are integral to the web. ChromeOS doesn't ship without it.