* Posts by t_lark

32 posts • joined 16 Sep 2010

Fed up with Windows? Linux too easy? Get weird, go ALTERNATIVE


Are you a religious nut?

Then maybe Temple OS is for you http://www.templeos.org/

Lasers capture 3D images from a kilometre away


Re: What university are you saying? Edin-who? HERIOT WATT!

I got my PhD at "University of Edinburgh" and now work at "Heriot-Watt University". I have never heard of a Edinburgh University.

What Compsci textbooks don't tell you: Real world code sucks


Good Example of Code

Thought I would buck the trend and point out some beautiful code I discovered the other day: LinuxCNC. A modular framework that allows you to swap out software modules for hardware modules (!). Config the interconnects in XML. It has some complicated modules in C++ (e.g. decent Kalman filtering), it has some deceptively simple module (add two inputs and other basic arithmetic). Now here is the kicker: its got its own realtime scheduler, so you can build complex modules by joining up simple modules if the task of building (a realtime version) what you want is too much to bite off. Furthermore, it has its own user space, with python bindings, so that UI type work can be done without the real-time hassles and in an easy language. My god! It is such an awesome design! The only real neg is that its a bitch to compile, but I felt uplifted by going through its source

Fish grow ‘hands’ in genetic experiment


we should give dolphins hands

Revealed: Google's manual for its unseen humans who rate the web


I expect the statistical tools used decide where to apply human labellers is indeed glamorous (from a statistician's point of view).

Ten Linux apps you must install


Noob list

not knowing print screen gets a screenshot (works on windows too!) is one of many oversights that suggests the author has only just started learning linux. *The* major omission is grep. Another good tool is locate.

grep -r "regex" .

does a recursive sub directory inside files for the regex. Perfect for finding where the debug message you are currently viewing came from. Also has many uses in filtering the output from some other command

Mystery martian object is relic of (our) civilisation


Looks like a prawn

Brit turns Comp Sci coursework into $100k glad-rags search biz


@sooty most undergrads keep their IP at university. Most PhDs too (but smaller proportion), staff don't (these days). There is no universal treatment of IP across Unis though, its depends where you are.

Well-funded Meteor poised to impact web development


"How is this different from writing a client- server PC application in any old language like we did already in late 1980's / early 1990's?"

-Servers could not push to clients easily

-firewalls broke those applications

-deployment from web interface not hard disk


This tech is probably nothing that revolutionary, but a load of existing components put into one coherent framework with a single language to serve both ends. I am somewhat interested, but google app engine is just too cheap that it keeps making me come back.

Microsoft: Azure now holds FOUR TREELLION objects



How did that happen! Were their loads of Microsoft shops desperate for cloud services but refusing to go near an ssh session? They waited 3-4 years until Microsoft made a nice interface in .net for it? Jeez it shows how many sectors are still utterly dependant on XP.

Behind the lens of NASA's self-adapting ISS space telescope


Re: Testing hell

Erm, how do you know the hardware will solve the problem you are tackling? Reflashing software will not make up for actuators/signal processors that don't have the required control bandwidth.

Free CompSci 101 finally launches this month

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As a C++/Python/Java/JavaScript developer (who learn BASIC first), I think Javascript would also be my number 1 choice for teaching a programming course over the web.



The Bozier Mench combo has really worked well. Love the site. Maybe its time to monetize it with some regenerating popups.

UPDATE: GAGA team hunts down grass-smoking ROBOT


SLAM - Simultaneous Localization and Mapping

Check out the robot operating system at www.ros.org . Lots of people build lots of different SLAM solutions. One major problem is the correspondence problem, how to you know which spacial features are distinct. With active beacons this can be encoded. So have beacons chirping at different frequencies and then detect those frequencies by differencing an image at the same rates i.e. add the current image to the accumulator, then subtract it from the accumulator every X seconds. The accumulator with pick out pixels that vary at the same frequency, whereas other pixel values will cancel each other out.

Turn a camera into a omni direction camera by pointing it at a ball bearing. Bit of image warping and you can now get the *direction* of all distinct beacons. So now you can do "bearing only SLAM" (probably already in ROS I expect). A compass is also a useful addition for this kind of localization. Normal digital cameras = IR cameras after the removal of the IR filter.

Let us know if you need any help through Edinburgh Hacklab. We have alot of robotacists members (including me a.k.a. Larkworthy).

Quantum computing in our lifetime - IBM breakthrough



I think logistics will be a big winner. Yay! 5p shaved off the cost of *everything*. (that and other graphy things like gene analysis)

Node.js Native breakthrough: cloudy C++ on steroids


Re: Example Of Fortran Optimization

nomenclature clash. I meant persistent data-structures like path copying e.g. http://hackerboss.com/copy-on-write-101-part-1-what-is-it/ *not* persistent like databases. Pointer ownership is difficult to work out for non GC environments. The difference between using a persistent algorithm and a non persistent one can be an order of complexity on an algorithm, so if C++ is stuck with the O(n) implementation while Java is might achieve O(log(n)) (with the occasional freeze though :/ ). Nor can you get rid of that freeze either by the normal trick of caching objects for the same reasons you can't implement the algorithm in c++, lack of clear ownership of objects.


65 comments missing the point

My profiler and I build performance systems at the world class level.

I use Java for high speed advanced data-structures as you 1. can't build persistent data structures in a non-garbage collected language, and 2. it can be blindingly fast if you know what your are doing.

I use C++ sparingly for signal processing (images, sound) because of the hacks you can pull off, but I minimize its usage because of the increased development time and debugging. 90% of runtime cost is on one part of the system, so I write that bit in C++ *once I have identified it*.

I use python for test harness and overall glue, because you can rearrange an application very easily with it and there is no annoying compile routine.

I use javascript for the pretty interface because running this via a web browser is the coolest way of making an appliance application platform independent.

I use Matlab for intelligence and visualization.

I glue these all together using a middle ware solution (ROS).

My development time is my employer's main cost. Premature optimization occurs at the language selection level. Their is a silver bullet, it's called mixed language development, but it requires forcing yourself to learn new paradigms all the time (working on better functional stuff at the moment, looks cool)

Sysadmins: Don't get in your own way

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All I care about is the length of time I have to stand in a queue. Automated checkouts have definitely improved my Tesco experience in that respect. It's totally worth the occasional baggage hiccup IMHO.

PS drop box is the more accepted "it just works" technology for rambling anecdotes, with the better backstory that they are making a ton of money while Tesco is losing market share.

SOPA is dead. Are you happy now?


I find an individual techie has huge amounts of logical conflict over these IP issues:-

-Role of software patents

-GPL infringement by commercial companies

-Open source infringement of commercial patents

-China stealing IP


You can't have it all ways....

Golden booty-shakin' bug named after pop diva Beyoncé


I did a similar image search and got a withered maid staring at a mac book http://2.bp.blogspot.com/_2rQqgKRpg_4/THwieDLDvyI/AAAAAAAABMo/c8OKHF9Ijlk/s400/LS_11.jHmmmm. An onerous premonition for the future of Beyonce?

Boffing boffins create 3D map of orgasmic female brain


@David W.

1. neuroscience is biological science and therefore its more likely to be staffed by a squadron of females. It isn't comp sci, or physics.

2. In these kinds of exploratory works, its likely the participant *is* the scientist. Much less paperwork and no need to pay the participant.

I expect the post climax prefrontal excitation to be be the investigator analysing her results.

Robot ostrich spy outpaces world’s fastest sprinters


Simulations are used to do the normal engineering math that is impossible to do by empirical trial and error. Complaining simulation has been used to design the parts is like saying we shouldn't use equations to build bridges.

Look at some state of the art style passive walkers http://techland.time.com/2011/10/26/watch-a-robot-that-can-walk-without-motors-or-electricity/

Computers are used to make sure the legs are balanced and will operate passively (or in this case use one motor to drive many joints), which was highlighted as an innovation in this work.

Dubstep ringtone wins Nokia compo


I love the new direction music is taking. This sort of music is experimental, and is breaking the tyranny of the octave that has enslaved your ear perceptions for too long. The chord Jimmy Hendrix plays on purple haze was called the "Devils Chord" in the 18th century, and was to be avoided. The noises you are hearing emanating from dubstep are the next set of taboo audio sensations that will one day become Mozarts of their times. Perhaps not the Nokia tune itself, but you got to shift through the dirt before you find gold.

Yes, many of you are all too old to appreciate a new paradigm.

High-frequency traders attract regulator’s interest


Well, they make money by arbitraging across continents using high speed, low latency networks. In some sense their value is distributing market information faster than anyone else can, hence their technical prowess.Its far from certain that the flash crash was a high frequency trading issue.

Final insult for Full Tilt as Channel Islands kill its licence


Re: Maybe I'm missing something here...

Um, thats why you lost. Skilled poker players are make informed decisions based on the probability of hand improvement ("outs"). Online poker playing is about calculating your risk better than the other players, and taking the long term average rewards. Even face to face tournaments are only weak modulations of the mathematics. Poker is a genuinely boring stats game (fold 9 in 10 hands for example).

Chinese giant Alibaba offers 'Cloudphone'


Ali Baba

1st. Ali Baba was not a thief.

2nd. Alibaba operates smoothly already in the middle east.

WW2 naval dazzle-camo 'could beat Taliban RPGs'


@Dave 62

No, Dave 62, I do robotics. In my field some people use psychological data generated in manipulation tasks to understand the functional block diagram of how humans recompute trajectories in uncertain situations (in order to make our robots manipulate better).

I am defending an area of research that I am not personally involved in, but that I see has genuine scientific value in other areas.

I find people like you that leap to the rubbishing of other peoples work generally ignorant. I don't think you have a broad enough range of knowledge in enough areas to make that call rationally.

Paleontologists: Standardise 3D laser image files, for pity's sake


RE:Not very impressed by their scanning resolution either.

1.2mm is pretty good accuracy if we are talking absolutely.

PHP apps plagued by Mark of the Beast bug

IT Angle

Difficult issues

just to wade in here, I am not a PHP programmer but I understand their issues. PHP targets multiple architectures but they want the same precision so the 64 bit floating point arithmetic needs to be retargetted for a 32 bit platform, or something like that.

Stuff like sin and e etc. have to be calculated using standard operations on a computer. Taylors expansions provide us with an iterative method for successively improving an approximation to ANY FUNCTION using operations we have defined. So presumably during stuffing 64 bit float arithmatic into a 32 bit arcitecture they had do do something along the lines for applying a taylors expansion. The thing is, its not very efficient.

I wrote a physics engine once in Java and found 79% of my processing time was spent in sin(), because of these iterative processes. I tried replacing with lookup table but this caused aliasing in the simulations, so I had to write my own sin with a controllable error term. http://www.java-gaming.org/index.php/topic,16296.msg130032.html#msg130032 . Bugs are easy, the taylors might not terminate if anything weird happens when trying to meet the desired error in the approximation. Unless of course, you have defensive checks in every iteration of your taylors expansion.

My main point (finally) is that when you are working at this level, you are already annoyed by how slow the taylors expansion is. Presumably every floating point operation is having to go through an annoyingly slow step already, so they probably down want to bog it down even further by coding a taylors defensive checks. Probably to fix that bug properly they will have to slow down floating point arithmetic 10% FOR EVERY FRICKIN FLOAT operation. You though PHP was slow already :/ If they are lucky they might be able to catogarize the bug at a higher level and say if the float is above X then reduce reduce the error term, then its jsut one conditional overhead at the beginning of the operation, but these issues are head scratchers usually. Portability is the issue. Java has a strictfp keyword which is all about this kind of thing.

IBM races bits along a nanowire track



How irritating! IBM has taken the time to employ some well paid geniuses, provide them with very expensive tools, for them to perform quantum hacking, at atomic precision and at nano scale timings; only to convert the results, at the final step, into a set of units SO incredibly vague and ambiguous that they can hardly be considered quantative units at all.

PS, for those here believing IBM must of meant the data required to record a whole year, you have been suckered by the PR. They gave you a vague number and you have chosen the largest possible interpretation

Google robo cars drive selves on public streets

This post has been deleted by a moderator

Custom superchippery pulls 3D from 2D images like humans



I think this article is over hyped.

Firstly from the speed up perspective. From the video: x60 than an Intel i7 and most importantly x2 a GPU. So I can replicate the functionality with two GPU's with sli then. Hardly replacing a megaton supercomputer.

Secondly, the actual science is a little dubious. One reason why the brain does well because it has estimates of how big everything should be, but this chip is just a convolution farm without any shape priors. So at a stretch it mimics the very first neural layer, but not the visual *system*.

Excellent use of an FPGA though, I like the tech, but not some of the claims. To get better 3D from a moving camera the more accurate way would be to use the separate frames as views from different perspectives (and generalizations thereof). Doing that in real time would be a challenge.

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