Backstory It started that I would like to have my students to vote for their peers’ presentations. And I don’t like to do it the old fashion paper way. I thought of using some commercial products. But since I was reading a little bit JavaScript couple weeks ago, I guess it probably would be a…
This is a re-post of a blog post I wrote for my department blog couple years ago. I just read it again and I found it still relevant. For those of you who have been to my office or have taken my classes will know that I am a big Linux fan. I started to…
I recently got a used X230 tablet and tried to have some fun on it. StarCraft runs well with wine but cannot run on full screen. One possible solution is to open another X server following this post. But I need some tweaks for 14.04 and for touch and stylus to work. First, one needs to add Section…
There is no excerpt because this is a protected post.
I am in Shanghai a couple days and it is quite inconvenient with many websites blocked. I heard about “breaking” the wall but I didn’t realize it is quite fast and easy. All one needs is a software called goagent. It takes advantage of the google app engine. Here, I will assume that ones already…
A simple simulation of M/M/1 queue with Matlab. The distribution of the number of “packets” in the system is computed and compared with the theoretical result. delta=0.1; % simulation step in sec lambda=0.1; % arrival rate in packets per second mu=0.2; % departure rate in packets per second rho=lambda/mu; M=50*3600/delta; % number of simulation step…
Below is a simple Matlab code to simulate a Poisson process. The interarrival times were computed and recorded in int_times. The times are then grouped into bins of 10 seconds in width and the counts are stored in count. lambda=1/60; % arrival rate per second (1 minute per packet) T=10*3600; % simulation time in second…
As a cantonese from HK, I didn’t know how to “type from my mouth” as a kid. I learned Cangjie during high school but I have never become really proficient with it. Chinese is not exactly a phonetic language. But when I write IM, email, or just blog in Chinese. I found it much better…
Here are some notes after listening to a coursera lecture of Algorithm 1 by Professor Roughgarden at Stanford. The goal of a Bloom filter is to provide a space efficient hash for some data entries. The insertion and validation of an entry are very efficient. But a trade-off is that deletion is not possible and…
My favorite screencast solution for now is summarized here. I use the following command to do fullscreen (assume resolution is 1024×768) screencast ffmpeg -f alsa -ac 2 -i pulse -f x11grab -r 15 -s 1024×768 -i :0.0 -acodec flac -vcodec mpeg4 -sameq -y ~/out.mkv ; To restrict capture to a window, one can run to…