Daniel Lemire's blog

Control a NASA helicopter using AJAX

, 1 min read

Will exposes his secret NASA work. Thanks to him, you can fly a NASA helicopter using AJAX. It is a very pretty and neat looking web application, very modern and worth playing with. It took me some doing before I could get the helicopter to actually cycle through its targets though, but it was well…

Do not open external links in new windows

, 1 min read

A university official who shall remain nameless wrote to me this morning the following sentence regarding our web sites: it is important that links to external sites appear as a new window The official claims this is for well-established legal reasons. When Tim Berners-Lee invented the web in…

New Electronic Mathematics Journal For Students

, 2 min read

Franklin sent me the following announcement, pass it along: NEW ELECTRONIC MATHEMATICS JOURNAL FOR STUDENT PAPERS. http://aejm.ca Dear Colleague, We would like to draw your attention to an exciting opportunity for your students to publish their research papers. The Atlantic Electronic Journal of…

After Oracle and Microsoft, IBM sets its database free

, 1 min read

I wrote about this two months ago, but IBM finally announced it is setting a limited version of DB2 free. It was unavoidable after Microsoft and Oracle doing the same. It seems clear that the various free open source databases, MySQL, PostgreSQL, MaxDB, Firebird and Ingres, are putting a lot of…

How to make external links exit HTML frames?

, 1 min read

Generally, avoiding copy and paste is a great idea whether you are designing a web page or sending people on the moon. A common problem with the badly constructed web sites relying on HTML frames is that external links are loaded within the frame which poses serious usability issues. A better…

Looking For Great Open Source Graph Library

, 1 min read

I’m currently looking for good open source graph theory. It needs to support basic algorithms for problems like minimum cost maximum flow. I need a GPL-compatible license. In C++, I found that the Boost library has something pretty complete together with Python wrapping. But I hate working with…

NRC Promoting Slope One

, 1 min read

My old research group at NRC is promoting the Slope One algorithm for recommender systems: The performance of Slope-One is remarkable; recommendations can be culled from collection of a million rated songs in a matter of seconds. Note that the people who make this statement are only indirectly…

kd-tree applet

, 1 min read

k-dimensional trees are a clever way to select all points in a rectangle using O(sqrt(n)+k) time where n is the total number of points and k is the number of points in the range. I usually don’t care for applets as a way to illustrate results (though I have two on my own web site doing just…

Why libxml2 takes forever to transform XHTML files

, 1 min read

For my Online XML Course, I process lots and lots of XHTML content using XSLT. Up until now, I avoided the libxml2 XSLT processor (xstlproc) because it was unacceptably slow. Today, I found out what is happening. It loads all of the XHTML DTD files from W3C each and every time it processes an XHTML…

Quasi-Monotonic Segmentation Talk in Ottawa

, 1 min read

I’m giving a talk next week at the Text Analysis and Machine Learning Group (TAMALE) seminar at the University of Ottawa. I will talk on Optimal Linear Time Algorithm for Quasi-Monotonic Segmentation. It is not directly related to text and machine learning, but many of the ideas from time series…

Saving Bandwidth with CSSTidy

, 1 min read

My CSS files get verbose over time. CSS is just not a great language or else, I’m not very good at it. Anyhow, I found out about CSSTidy which is a nifty tool to optimize your CSS files. There is also an online version. CSS optimization is a cool topic and it might get to be quite a challenge as…