Where is /var/log/messages on Ubuntu 12.04-b1 (Precise) ?

To enable /var/log/messages is disabled in the beta-1 version of Ubuntu Precise Pangolin (download here), do the following:

Edit /etc/rsyslog.d/50-default.conf and uncomment the lines

*.=info;*.=notice;*.=warn;\
auth,authpriv.none;\
cron,daemon.none;\
mail,news.none -/var/log/messages

Then restart the rsyslog daemon:

# service rsyslog restart

(Reference: Ubuntu forums)

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Distributed Mandelbrot computation with HTML5 workers

Computing fractals usually requires lots of CPU cycles and taking advantage of today’s multicore processors allows us to speed-up the computation. The HTML5 specification defines a new API for parallel computation known as Web Workers. In the example available here, the Mandelbrot figure is computed with HTML5 workers and displayed using an HTML5 canvas.

The Mandelbrot fractal figure

The distributed computation is made according to the scheduler/worker scheme.

The scheduler is responsible for starting the workers, feeding them with the description of their task, and drawing a dot on the canvas for each result received from a worker. Assuming that the work is distributed among n workers, the drawing area is divided in n equal parts and each worker receives its part of the work. A worker iterates on the dots contained in its area and evaluates the Mandelbrot value for each dot. Each computed value is then communicated to the scheduler through the event handling system defined by the web workers API.

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NetBeans mobile device emulator fails on x64 Linux system

The mobile device emulator fails to start with this error:

java.lang.UnsatisfiedLinkError: /home/myuser/WTK2.5.1/bin/sublime.so: /home/myuser/WTK2.5.1/bin/sublime.so: wrong ELF class: ELFCLASS32 (Possible cause: architecture word width mismatch)

My config: Ubuntu Karmic x64, OpenJDK-6 x64, NetBeans-6.8

The solution in my case is to change the vm used by the emulator:

Install the 32 bits java vm:

$ sudo apt-get install ia32-sun-java6-bin

Then edit netbeans_home/mobility8/WTK2.5.2/bin/emulator and set

javapathtowtk=/usr/lib/jvm/ia32-java-6-sun/bin/

with the trailing slash!

Now it works.

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A First Contact with JQuery

JQuery is a javascript library based on a query+computation principle. A jQuery statement is made of two parts: a query on the DOM elements and a computation applied to all elements selected by the query.

Some jQuery based libraries:

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