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…
I came across broken dependency trying to install wine. This happens after I try to install Intel Linux driver. Somehow it uninstalled wine and I couldn’t reinstall it. The problem is probably due to the “newer version” of applications I installed before I upgrade the machine from 10.04. It took me many hours finding a…
It takes me quite a while for me to figure out how to clone my screen to the projector. The default setting (two separate screens) may be reasonable for power point presentation. But I would like to take advantage of the stylus during my presentation. Cloning the display is of course a better choice for…
Got my cheap used X61 but the touchscreen is way off. I tried to calibrate it with this and this post but it just doesn’t work in my case. To be fair, xinput-calibrator suggested by the posts is very useful. Just the calibrated data is not registered. After some more search, find the command xsetwacom….
Just installed another 12.04 to a X61 tablet from ebay. It is one of my favorite machine as I can write notes on that and it is cheap ($150 from ebay). And with xournal, I don’t even need to print out stuff and rescan if I need to sign some document (just use the annotate…
My ubuntu box does not always configure wireless connection correctly. Luckily, setting connection on command line is rather easy. I followed the comment by Savage for this guide (or I guess this one is kind of the same). It didn’t work the first shot for me. But it worked after some slight modifications. You may have a different device,…