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Jarvis’ March

In computational geometry, Jarvis’ march or gift wrapping algorithm is used to compute the convex hull of a given set of points. The algorithm has broad range of applications in mathematics and computer science practically in pattern recognition, image processing, statistics, geographic information system (GIS) and game theory. Convex hull or convex envelope of a…

Backup your Mac with AppleScript

All programmers are lazy. They want to automate tasks as much as they can. Because of this uniquely great habit, they have developed countless of useful software. Ok. I am lazy. I have been using rsync to sync folders I am working on between my Macs. I have been using command line scripts in Terminal for…

The new WordPress

Just finished upgrading WordPress to 2.7.1 with a totally new user interface. I still prefer the one in 2.6.x so I guess I need a little time to get use to the new UI. The upgrade is inevitable because some of my sites were affected by Yahoo! Counter  malicious malware. It is a nasty injection…

Finder hang in Leopard

When I returned home this evening, LA told me her applications had hung. I checked and found not only that, the Finder was not responsive too. I had no choice but to power off and to restart the Mac Mini again. This had also affected my user account. The Finder had failed to launch after…

Subversion client hangs after post-commit

I had been hit by this problem since I setup Subversion on Ubuntu in January. The svnserve was properly invoked on Ubuntu server but whenever any svn client was trying to commit something back to the server, the client would hang for hours before it prompted an error: “Connection reset by peers.” I searched all…

Hacker and Cracker

I received an email from my sister, M. In her email, she pointed out I should not label myself as “hacker”. Well, I could not agree to her opinion so I decided to write this post entry to clear the name for all hackers. Many people have watched too much Hollywood movies and have developed…

IP Flooding

I am experiencing IP flooding on my router. It notifies me by email about this attack. Right now, I have identified the source and hopefully I can nail this attacker soon. This is not the first time I experience IP flooding. I have received quite many email notifications in the past 3 weeks but I…

Lost your password?

There goes year-end and you need to prepare your new year budget. You retrieve an Excel budgeting file to work on. You have not been touching this file for a year and you encounter problem. You can’t remember the password to unlock the Excel file. You can’t recall where you have written down the password…

Information Forensics

What is information forensics? Information forensics is a science of investigation into systemic processes that produce information. Systemic processes utilize technology, primarily computing technology, in creating, delivering, storing, evaluating and processing of information. This process is usually complement by manual process. Information forensics investigation dwells into the aspect of creation, operation and evolution of the…

HOWTO – SCIM and Ubuntu Gutsy Gibbon

Ubuntu 7.10, code named “Gutsy Gibbon”, has been released. I just finished upgrading from Feisty Fawn (7.04) to Gutsy Gibbon. The upgrade (downloading, unpacking, removing, installing, configuring and cleaning) took about 6 hours to complete. The upgrade was smooth and without any problems except it broke my scim. I have exhausted the search on Internet…