Patrick Getzmann and I have been exchanging email about a problem he had using some sample code I’d written for working with regular expressions in C++. I wasn’t much help, but Patrick figured it out. I wanted to post his…
Monthly Archives: January 2009
Log concave functions
Log concave functions have some very interesting and useful properties. I’ll list some of these shortly after a three definitions. A function is convex if the line segment joining two points on the graph lies above the graph. In symbols,…
First anniversary post
This blog began one year ago today. Thank you for reading my posts and thank you for all your encouragement, online and offline. If you enjoy reading this blog, please help other people discover it. Maybe you could tell a…
Posted in Uncategorized
Five principles for object oriented software engineering
In Scott Hanselman’s latest podcast, Robert C. Martin explains the SOLID principles for object oriented software design. SOLID is an acronym for the following: Single responsibility principle Open-closed principle Liskov substitution principle Interface segregation principle Dependency inversion principle Related blog…
PNG vs JPEG
Bill the Lizard answered an image compression question on StackOverflow by pointing out the image below that shows the difference between PNG and JPEG compression when applied to line drawings. The image comes from lbrandy.com. The left side of the…
Convex optimization
I’ve enjoyed following Stephen Boyd’s lectures on convex optimization. I stumbled across a draft version of his textbook a few years ago but didn’t realize at first that the author and the lecturer were the same person. I recommend the…
Introduction to computer virtualization
New post by Thomas Guest: Tell me about … Virtualization
Posted in Computing
Making screencasts with Jing
After seeing Jing as the top recommendation in a list of teaching tools, I decided to look into it. This two-minute video gives a good introduction to what the tool can do. In a nutshell, Jing makes it very easy…
Posted in Computing
A priest, a Levite, and a Samaritan walk into a bar …
A rabbi, a priest, and a preacher walk into a bar. The bartender looks up and says “Is this some sort of joke?” Many jokes follow the pattern of three people doing something. The first two establish a pattern as…
Posted in Uncategorized
Taking your code out for a walk
I posted two articles on the Reproducible Ideas blog this morning. Taking your code out for a walk Just because you haven’t changed your code doesn’t mean it still works. CiSE special issue on reproducible research The latest issue of…
Hard disk array failure probabilities
The acronym RAID originally stood for Redundant Array of Inexpensive Disks. The idea is to create reliable disk storage using multiple drives that are not so reliable individually. Data is stored in such a way that if one drive fails,…
Leaky abstractions and hockey stick learning curves
Michael Lugo wrote a blog post Turtles all the way down that links to a cartoon in which someone explains how a compiler works by diving through layers of abstraction from software to hardware to electrons to quantum physics. You…
