eXTReMe Tracker
Feb 262009
 

Over the years that I have stayed underneath the Alabama skies, I have grown more and more enchanted by them. It is one of life’s simple pleasures – looking up and seeing blue skies above. And in Alabama, its especially blue.

Here are some pictures I took in Birmingham, and one when I was on my way to Birmingham.

Around Highland Avenue in Birmingham
Around Highland Avenue in Birmingham

This is a picture on my way home, which is on Highland Avenue. I often walk gazing up in the sky during winter months because thats when we have the most clear skies.

View from the Bridge atop the Tennessee River on I-65
View from the Bridge atop the Tennessee River on I-65

View from the Tennessee River Bridge
View from the Tennessee River Bridge

About a week back on my way back from Huntsville, Alabama, we were crossing the I-65 bridge over the Tennessee river. Now first and foremost, the bridge itself is quite beautiful. I wish I could tell you the architectural name for that bridge but it slips my memory. But I digress. As you are crossing the Tennessee river, the view is absolutely marvellous. Its a wide river with lush vegetation along its banks and an equally beautiful sky above.

Fluffy clouds over the Southside Baptist Church
Fluffy clouds over the Southside Baptist Church

A few days back, the weather was slightly cloudy. But despite the cloudy weather, one still sees how lovely the fluffy clouds appear around here. This picture was in front of the Southside Baptist Church on the 10th St.

Tree getting ready for spring beneath blue skies
Tree getting ready for spring beneath blue skies

Spring is already making its appearance in Birmingham. As I was walking down a sidewalk, I noticed a tree that was getting ready for its spring bloom. Tiny leaves and flower buds were coming up all over this tree. What was even more beautiful was the whole setup. The tree getting ready to blossom underneath a cloudy blue sky. Yes, cloudy blue sky – its possible and I’ve seen it, and now you have too.

Feb 252009
 

Today’s update for Ubuntu 9.04 (Jaunty Jackalope Alpha 4) broke the audio mixer and the volume control modules. This update was for in kernel 2.6.28.8. Technically there was nothing modified in the audio modules, but the updates changed some of the user settings which disabled the user from accessing audio modules.

The workaround for this problem is quite simple. In the Terminal run the following command:

sudo adduser your_username audio

Restart the computer and you have access to all the audio devices like before.

Feb 182009
 

This evening I took a snapshot of my desk (which holds my desktop) with my cellphone camera. After transferring it via bluetooth, I opened the image and it was rather amusing to see the exact image of desk inside of an identical image. So just out of curiousity I snapped another photo with roughly the same FOV as before and loaded it on the computer, and again took a picture of that.

Photo iterations: or photo within photo

Photo iterations: or photo within photo

The picture looks quite interesting, as it depicts the same object at different time points within the same spatial space. I don’t see any artistic value in this picture, but what I do see is a lot of potential for philosophical discussion about time and space and how we can represent variations in time within a 2D space.

Feb 172009
 

A few days ago an article appeared on geekzone that described how the KDE and Gnome based linux desktop systems are vulnerable to virus and trojans. The point that jumped out was a statement by the blog author: “False sense of security is worse than no security”, and I’ve been guilty of having this false sense of security all along. By all along I mean whenever I was logged in to some Linux distro.

The article is titled: How to write a Linux virus in 5 easy steps

Linux is vulnerable to Viruses and Trojans

Linux is vulnerable to Viruses and Trojans

Its an interesting read, and one can only hope that everyone in the Linux community takes this as a serious flaw in their beloved OSs and helps out in addressing this issue whichever way they can.

Feb 112009
 

There were unmet dependencies (libx264-59) for vlc and mplayer in the latest release of Jaunty Alpha. A bug report was filed by several users on launchpad.net

One of the users posted this workaround to get both mplayer and VLC working in Ubuntu (9.04) Alpha 4.

To solve the problem, just get libx264 here:
http://packages.ubuntu.com/us/intrepid/i386/libx264-59/download
Just installed it manually (sudo dpkg -i libx264-59_0.svn20080408-0.0ubuntu1_i386.deb)
I then installed mplayer and vlc using medibuntu repos.

Running:

sudo apt-get install mplayer vlc

Gets these packages working!

Feb 102009
 

The system beep is one of the most distracting and annoying occurrences when you are doing some constructive work. Be it working in a text editor, or a terminal, or a program window – wherever a sound notification is programmed into any module, it emits a fairly audible beep. To disable the beep, we have to disable the PC speaker by adding it to the blacklist.

sudo gedit /etc/modprobe.d/blacklist

Add the following line to the end of that file:

blacklist pcspkr

Save and exit. Then in terminal,

sudo modprobe -r pcspkr

This completely turns off the speaker. You won’t hear your system beep, even if there is something truly wrong. If you are doing something critical and need to rely on the beeps, comment out the line from the blacklist and run the modprobe command. Beeping will restart.

Feb 102009
 

Recently I bought a student version of Matlab2008b. It was for Linux platform. Here’s my experience with installing the program on 64-bit Linux (Debian) architecture, what problems arose along the way and how they were addressed – with help from Mathworks tech support.

Matlab at work

Matlab at work

Installing Matlab 7.7 (i.e. Matlab2008b) the old fashioned way was a breeze, but getting it to actually run on 64-bit architecture involved a few steps, which I didn’t know. I sent a query to Mathworks tech support saying:

The installation files were able to successfully install Matlab2008b on Ubuntu 9.04 (Jaunty), however, the program failed to load since it cannot find the jre files for 64-bit architecture. Is there a workaround for running the 32-bit program on 64-bit platform?

And they replied with a procedure to be followed to make that happen:

Yes – here is a full walkthrough:

1) When running the MATLAB installer (install_unix.sh) use the -glnx86 flag.  This will allow it to install properly on a 64-bit Linux machine:

./install_unix.sh -glnx86 -t

2) Once the installer is finished, you will need to activate through mathworks.com, as the activation client will not work properly on 64-bit computers.  To do so, follow the instructions below:

http://www.mathworks.com/support/solutions/data/1-3YZBZ6.html?solution=1-3YZBZ6

3) Once MATLAB is installed and activated, you will need to run MATLAB using the same -glnx86 flag that you used to install:

$MATLAB/bin/matlab -glnx86

(where $MATLAB is the MATLAB installation folder)

NOTE: Some users have problems loading the JRE when running in this configuration.  Creating a symlink in $MATLAB/sys/java/jre named glnxa64 pointing to glnx86 should resolve this issue.  You can do this with the following command:

ln -s $MATLAB/sys/java/jre/glnx86 $MATLAB/sys/java/jre/glnxa64

And now it works. Haven’t had any GUI crash on me yet, but it been less than an hour since I’ve been using it. One way to avoid typing matlab -glnx86 before each launch is to create a local alias.

gedit ~/.bashrc

Under one of the listing for aliases, you can type in:

alias mat='matlab -glnx86 &'

Save and exit. Then onward, you can launch the program by simply typing in mat in the terminal.

In case your compiz is enabled, you might not see the menus correctly. To fix that problem, you have to run the following command at the terminal.

export MATLAB_JAVA=/usr/lib/jvm/java-6-sun/jre/
Feb 092009
 

Some of the repositories which hold the libraries for mplayer seem to be broken in the Alpha 4 release of Ubuntu 9.04 (Jaunty Jackalope). What’s surprising is that the mplayer installation in Alpha 3 meets all the dependencies and fetches the files correctly, however that for Alpha 4 don’t.

One workaround for vlc is to install libx264-dev, and then install VLC:

$sudo apt-get install libx264-dev vlc

This still leaves unmet dependencies for mplayer.

rick@lithium:~$ sudo apt-get install mplayer
Reading package lists… Done
Building dependency tree
Reading state information… Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
mplayer: Depends: libx264-59 (>= 1:0.svn20080408) but it is not installable
E: Broken packages
rick@lithium:~$

Feb 032009
 

After running the update commands yesterday:

sudo apt-get update && sudo apt-get upgrade

There were a few nvidia video card drivers that got installed. There were several of them;

fglrx-modaliases
nvidia-173-modaliases
nvidia-177-modaliases
nvidia-180-modaliases
nvidia-71-modaliases
nvidia-96-modaliases

Once these modaliases were installed, I performed a search for hardware drivers. This time the search showed that there were several drivers that could work with my Nvidia GeForce 7300 graphics card.

Nvidia graphics drivers after Jaunty update (Feb 2, 2009)

Nvidia graphics drivers after Jaunty update (Feb 2, 2009)

The recommended driver was version 180. After installing the driver, the computer needs to be restarted for the driver to take effect.  Accordingly, I restarted the computer and now the Nvidia graphics are fully enabled.

One of programs that I use frequently is still quite buggy. The gnome-do program, that performs the same functions as Quicksilver (Mac) was working really well under Intrepid. It keeps crashing all the time under Jaunty. By the time Jaunty is in Alpha 4, I think the problem would be sorted out.

While the nividia graphics card drivers have been release for Jaunty, the ones for ATI still aren’t. The graphics on my Toshiba Satellite that has an ATI graphics accelerator card are still using the system memory. We’ll have to wait for the ATI drivers in order for the card to start working in Ubuntu 9.04.

Feb 032009
 

In 1858, two German mathematicians, August Ferdinand Möbius and Johann Benedict Listing, independently discovered what is popularly known as the Möbius strip. The characteristic feature of Möbius strip is that it is a surface with single side. In its most simplest form a Moebius strip can be constructed out a a strip of paper which is twisted halfway and the ends joined together. If one were to start tracing a surface, by the time they complete one trace they find that they are tracing the opposite side of the paper than the one from which they started. Go another round and you come back to the same side.

Basic Moebius strip (twisted ribbon)

Basic Moebius strip (twisted ribbon)

A Mobius strip can be expressed mathematically in several diffferent forms. Geometric term for the the form exhibited by a Mobius strip is a Chiral. The parametric equations for a Moebius Strip can be expressed as:

x(u,v) = cos(u) + v*cos(u/2)*cos(u)
y(u,v) = sin(u) + v*cos(u/2)*sin(u)
z(u,v) = v * sin(u/2)
Default values for u and v:
u = [0, 2π] for one complete loop;, v = [-0.4, 0.4]

An equation for constructing a Moebius Strip using Matlab can be found at the Univesity of Stutgart’s mathematic department – Matlab code repository.

Rendering of Moebius strip using Matlab

Rendering of Moebius strip using Matlab

Among the most famous artwork using a Moebius strip is the one by M.C.Escher, which has a grid in the shape of gigure-8 Moebius strip with ants crawling on different sections along the strip.

M. C. Escher - Moebius Strip (insects)

M. C. Escher - Moebius Strip II (insects)

M.C.Escher has another piece of art in the form of a Moebius strip. This one has 3/2 twists instead of 1/2 as in the basic strip. By playing around with number of twists, one can create beautiful and complex loops.

M. C. Escher - Moebius Strip (twine)

M. C. Escher - Moebius Strip I (ribbon)

A simple, yet intriguing model of a Moebius strip is the one where a 1/2 twist Moebius strip is constructed from a transparent strip of plastic with the word Möbius written on it.

Moebius Strip written onto a transparent Moebius Strip

Moebius Strip written onto a transparent Moebius Strip

One of the most common example of a Moebius strip one encounters on a day to day basis is the Recycling sysmbol which has three foldeed arrows forming a loop. The folded arrows aren’t identical. One of the arrows folds in the opposite sides from the remaining two arrows. The design of recycling symbol appears somewhat similar to the Escher’s artwork with 3/2 twists.

Commonplace use of Moebius Strip - Recycling Symbol

Commonplace use of Moebius Strip - Recycling Symbol

This comic strip in the form of a infinitely repeating sequence of a stick figure kicking a a football at an unsuspecting stick figure and knocking it down is yet another example of silly, yet creative Moebius stripping.

Cartoon depiction of a continuous reel Moebius Strip

Cartoon depiction of a continuous reel Moebius Strip

Origami art, i.e. the art of paper folding, can be used to create some incredible shapes simply by folding a piece of paper. Here is an example of a Moebius strip created with Origami folding. The corrugated pattern on the strip makes it appear quite classy.

Origami paper folding - Moebius Strip

Origami paper folding - Moebius Strip

Here is an illustration of Moebius strip on a book cover. I haven’t been able to figure out of the illustration is an actual photograph if a jigsaw puzzle or it is merely a creation in Photoshop. Either way, a jigsaw puzzle that would form a jigsaw puzzle in the end would keep anyone occupied for several days – and several more if the structure keeps tumbling every now and then.

Moebius Strip depicted as a jigsaw puzzle on a book cover

Moebius Strip depicted as a jigsaw puzzle on a book cover

Creations that incorporate a Moebius strip are rather intriguing even as still images, but with animations they take on a spectacular form.  One is a interlocked gear chain and the other one is an escalator in the form of a half-twist Moebius strip.

Moebius strip in the form of a gear chain animation

Moebius strip in the form of a gear chain animation

Animation of Moebius Strip as an escalator

Animation of Moebius Strip as an escalator

Then there are some architectural models of Moebius strip in forms of scuptures that are placed at tourist attractions, and some that are placed in playgrounds.

Robert R. Wilson's sculpture of Moebius Strip at Ramsey Auditorium

Robert R. Wilson's sculpture of Moebius Strip at Ramsey Auditorium Fountain

Moebius Strip structure at a cildren's playground

Moebius Strip structure at a cildren's playground

Moebius Strip - 12-panel Moebius Climber at a playground

Moebius Strip - 12-panel Moebius Climber at a playground

Moebius Strip Jungle Gym near the Temple of Honor

Moebius Strip Jungle Gym near the Temple of Honor

And then there is a Moebius strip cake – how’s that for sweet!

Cake baked in the shape of a Moebius Strip

Cake baked in the shape of a Moebius Strip