B-Trees actually have superior cache performance compared to other types of trees (such as T-Trees or BST Trees). In part, this is because B-Trees have a higher density of actual data to pointers.
There is a tradeoff of computation (doing binary search inside the node) and amount of storage (keeping less pointers). In environments where memory access is much more expensive than a CPU instruction, it is preferable to perform these computations than to have to read all the extra pointer data to jump to the right places.
In fact, a breed of cache-friendly data structures are precisely based on the B+Trees but with even less pointers, having the algorithm compute these pointers instead (CSS-, CSB-Trees)
It is clear to everybody that iMessage is not a platform-independent to send messages today. Thus, there is still a need for BBM, SMS, and all.
However, the distribution of people who own iPhones is not as uniform as the author seems to imply. Sure, maybe there are only 5 iPhones for every 95 other phones; however, I know my girlfriend, parents, and close friends all own at least one iOS device. The service will remove the need for SMS for those who are in the same situation, and the extent to which this happens is not addressed here in any valuable form.
It is also true that GTalk may have a higher usage, and I'd be thrilled if iMessage worked with GTalk (I think). However, iMessage will be tightly integrated into the Phone application, which makes it much more convenient to use than any other IM service on the iPhone. Maybe iMessage/GTalk interoperability would make iMessage more effective; this doesn't mean as it stands iMessage will be ineffective.
You've probably seen this already, but have you considered the Harvard Extension School? I don't know the details, but I do know the extension school offers some classes taught by the same professors that teach regular Harvard classes.
An example of these classes is Prof. Michael Mitzenmacher's algorithm's class, which is both challenging and fun. I think the class is offered online and maybe in person during the summer.
(http://www.extension.harvard.edu/2010-11/courses/21462.jsp?c... )
It is sad to see some areas where people on average are doing significantly worse than the richest parts of the United States.
However, I find the choice of the term 'Third World America' to be particularly deceiving. Let's take Louisiana, for example, marked as amongst the worst regions according to the infographic. Median earnings are 28,000 and about 75% with at least high school education.
Now let's compare against Mexico's average. Mexico is not nearly as bad as other third world countries. Average earnings are about 7,000 USD/year [1] (and median earning is probably worse). Roughly have of Mexicans haven't completed their junior high school education (6th to 9th). These are national averages, though, which --unlike the infographic -- do not focus only on the poorest areas. The poorest areas are, of course, much worse.
I'm not trying to say with this that you shouldn't complain if others have it worse. I am just saying that this particular choice of wording is not realistic and, in my mind, took away from the credibility of the rest of the site .
I wouldn't call it to 'tweak' the data collection. He is simply normalizing the results to ignore the differences in language distribution.
This is normal and has nothing to do with how you choose to represent it.
It would have been meaningless to show any graph or table saying 'Python has the most messages with profanity" if the amount of Python projects is 80% of all the projects out there.
The link is not working for me; going to http://twitter.com/NokiaPlanB/ only shows the following quote: "there are no 'nine young investors', just one very bored engineer who really likes his iPhone"
If this is the case, then I guess that explains the anonimity.
They have fixed costs (independent from the number of tickets bought) in the form of payments for search results to ITA plus whatever company overhead (maintenance, salaries, etc).
Whether Hipmunk can afford improvements in user experience while earning thinner margins than the competition is not entirely obvious to me.
The point raised in the presentation is that as Hipmunk is better able to achieve price parity (say, via the ITA deal which will make better search results available to them), the prime differentiation will be the usability of the product.
The question is pretty legit; the long application asks a number of questions like how much you use desktop apps (Anything from MATLAB to Citrix), and also about your preference in Google products vs anything else (gmail, calendar, docs, etc).
Is there any indication to whether they are picking people with good fits (e.g. those who basically use all the Google products already) or are they just selecting people randomly, using the data provided just for stats and context to the person's inputs?
Of course the complexity will increase as a function of the number of features.
However, I'd make the following claims:
(1) Some of the functions are simply not that used. You can get by perfectly well without knowing what double and triple clicks on the home button, for example, If you don't know they exist, you will never even notice.
(2) iOS has less features than Android and arguably this makes it somehow less powerful but also less confusing for my mom (e.g. no task manager, no intents).
(3) Switching to a Mac was actually quite challenging coming from PC land ("where's maximize?", "where's a working Alt-Tab?", etc). I'd say the usability still kicks in as far as how easy it is to do your job for most after the learning curve has passed. Your mileage may vary, but I find myself enjoying using my Mac more than I ever did using Windows on my PC for usual tasks, and that's part of what makes it usable for me. I'd expect a similar phenomenon with iOS.
I got a message from BankSimple telling me that I was going to get an invite soon and asking me for feedback. I got really excited and responded with an e-mail, but never heard back from them. I'm not sure if I misinterpreted the original e-mail, but this was a huge letdown.
Did this happen to anyone else? In any case, best of luck to BankSimple. I can't wait to actually get to try the service. :)
I think this is a great idea, but having worked on benchmarking database structures in the past, I'd be weary of using them for any type of real benchmark.
For one, trying to model a real disk would get very complicated very fast. Say, the access time of the disk will be a function of the position on disk, so it would be unrealistic to get random delays when scanning a large chunk of contiguous data or by just having a few delays in a random-access heavy load would also be extremely unfair.
In short, trying to model complicated disk latencies is pretty hard, and usually if you are programming with some model of disk in mind, building a disk latency simulator under that same model may end up giving you a false sense of security.
For what it's worth, I'd favor getting a cheap hard disk and trying the load there instead.
I second this. I just graduated and as I was looking for a job and I interviewed for a bunch of companies.
One of them asked that I solve some programming challenges. Sure, I like puzzles and I like being challenged. However, at the time I was already being challenged by my thesis work, problem sets, interviews... it's hard to agree to make a huge time commitment just to get the right to a first round interview.
Since other hot startups/ cool companies (Google, FB) don't require this type of activity, it makes sense to me to think that a lot of people simply won't have the time to apply because they're busy solving more interesting puzzles.
I have bought more than a couple of CDs from CD Baby and thanks to them I've been able to connect with more than a couple of wonderful artists.
However, from Apple's perspective, it must have seemed like CD Baby was simply trying to make a profit simply by guaranteeing access to the Apple Store, and therefore Apple decided not to move forward in order to protect its brand.
I wouldn't first argue that Dvorak spits out 'ignorant bullshit' while claiming that all design preferences are equally valid.
I personally prefer the older Google Images. For one, I lose the ability to scroll the website immediately after finding it. I do this, for example, when I'm searching for some algorithm by first finding a diagram that I think is clearer and then going directly to read the explanation, or when searching for a recipe by looking for the image first.
I find the new interface to be slightly cluttered to use (with all the animations and uncomfortable feeling when scrolling), At some point, Yahoo (and others) had pretty cluttered interfaces and people eventually shifted to Google, commonly citing simplicity. For this reason, I find that taking the leap to 'everyone complains about changes' to trivialize the fact that many people may, in fact, appreciate simple interfaces.
There sometimes is a superior interface, and discussing the pros and cons of a new interface is very valuable.
The task you are splitting has to be sizeable enough that the setup costs of parallelization (in this case, going to every cashier to put your stuff and then going and picking it up) don't outweigh the potential benefits from parallelization.In this case, unless you are buying the whole store, it just doesn't make sense to bother splitting your shopping cart like this.
Further, if all the cashiers are busy at all the times being useful (ringing customers), you cannot possibly get a gain from splitting any further. There's no way you could improve the throughput of this system when every processing unit (cashier) is at the top of its utilization.