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Raphaël Pinson
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Raphaël Pinson

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So Lenovo has decided to let go of their standard, simple round charging plugs...
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Vous avez des airs :)
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The Opus codec becomes an IETF standard [LWN.net] - http://ae7.st/s/2q
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Explanations of all the strange Debian package names you always wondered about: http://wiki.debian.org/WhyTheName
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A lesson in shortcuts.

Long ago, as the design of the Unix file system was being worked out, the entries . and .. appeared, to make navigation easier. I'm not sure but I believe .. went in during the Version 2 rewrite, when the file system became hierarchical (it had a very different structure early on).  When one typed ls, however, these files appeared, so either Ken or Dennis added a simple test to the program. It was in assembler then, but the code in question was equivalent to something like this:
   if (name[0] == '.') continue;
This statement was a little shorter than what it should have been, which is
   if (strcmp(name, ".") == 0 || strcmp(name, "..") == 0) continue;
but hey, it was easy.

Two things resulted.

First, a bad precedent was set. A lot of other lazy programmers introduced bugs by making the same simplification. Actual files beginning with periods are often skipped when they should be counted.

Second, and much worse, the idea of a "hidden" or "dot" file was created. As a consequence, more lazy programmers started dropping files into everyone's home directory. I don't have all that much stuff installed on the machine I'm using to type this, but my home directory has about a hundred dot files and I don't even know what most of them are or whether they're still needed. Every file name evaluation that goes through my home directory is slowed down by this accumulated sludge.

I'm pretty sure the concept of a hidden file was an unintended consequence. It was certainly a mistake.

How many bugs and wasted CPU cycles and instances of human frustration (not to mention bad design) have resulted from that one small shortcut about  40 years ago?

Keep that in mind next time you want to cut a corner in your code.

(For those who object that dot files serve a purpose, I don't dispute that but counter that it's the files that serve the purpose, not the convention for their names. They could just as easily be in $HOME/cfg or $HOME/lib, which is what we did in Plan 9, which had no dot files. Lessons can be learned.)
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Received a printed version of https://github.com/raphink/geneve_1564 in the mail today #bible #latex #ebgaramond  
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Oui, on voit mes pieds ;-)
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Have him in circles
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+Vladimir Bulatov does it again!  At each moment, this movie shows you a tiling of the hyperbolic plane by pentagons, four meeting at each corner, mapped onto a disc with four slits cut out.  This mapping is conformal, meaning that it preserves angles.  As time passes, the hyperbolic plane rotates and we see this crazy movie.

For a more detailed explanation, with tons of great pictures, go here: http://bulatov.org/math/1001/

Here's the short version: there's a way to measure distances on a disk that makes it into a model of the hyperbolic plane.  There are actually a number of ways, but Bulatov - and Escher - use the Poincare disk model, because in this model straight lines look like portions of circles: very pretty.  Then, according to the Riemann mapping theorem you can map this disk in a conformal way onto a disk with 4 slits cut out.  The hard part is finding a formula for how to do it, and then implementing it on a computer.

For more details, try these picture-packed pages:

http://en.wikipedia.org/wiki/Conformal_map
http://en.wikipedia.org/wiki/Poincar%C3%A9_disk_model

and this more advanced one:

http://en.wikipedia.org/wiki/Riemann_mapping_theorem

#sciencesunday
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Do you love automated, devops-oriented sysadmin? Join us!
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Really thrilled that we're launching Google+ Local today! Another great example of how Google+ is making all of Google better. Huge congrats to the many teams involved. As Avni says in her post, we're just getting started. Much more Locally goodness to come!
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Have him in circles
400 people
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  • Camptocamp SA
    Systems Engineer, 2012 - present
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    Systems Engineer, 2010 - 2012
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    Systems Engineer, 2006 - 2010
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  • ENSMA
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Très bonne pizzas et un magret de canard excellent.
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reviewed 3 years ago
A unique place in Paris. Must see.
Public - 3 years ago
reviewed 3 years ago
5 reviews
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Les meilleurs burgers de Sophia.
Public - 3 years ago
reviewed 3 years ago
I stayed there for two nights with my wife and our daughter. The rooms are very nice and cosy, with very comfortable and large beds, and modern showers. The building is traditional, with a very nice and discrete decoration. We especially enjoyed the living room and the garden. The hotel is close to the center and the beach (croisette promenade). The owners speak quite a few languages, which is very helpful :-)
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reviewed 4 years ago