I'm Zigang "Ivan" Xiao,
an engineer in bay area.
I have a cat called Moose.

about me

I write about technical stuff in the field of computer science, with a focus on Machine Learning, my hobbies, including guitar playing and ballroom dancing, and my life in US. Some of my posts are written in Chinese.

A Comparison of Least Square, L2-regularization and L1-regularization

- - posted in machine learning

Recovered Coefficients by Different Methods
Recovered Coefficients by Different Methods

Problem Setting

Ordinary Least Square (OLS), L2-regularization and L1-regularization are all techniques of finding solutions in a linear system. However, they serve for different purposes. Recently, L1-regularization gains much attention due to its ability in finding sparse solutions. This post demonstrates this by comparing OLS, L2 and L1 regularization.

OS X: Reveal File in Console

- - posted in osx, tips

One of the neat things you can do in OS X is to reveal a file in Finder.app from some other applications. Turns out lots of the time, we also want to do that in the terminal. The following script helps you with that:

Send Ctrl-a in Tmux After Rebinding to It

- - posted in tips, tmux

While tmux provides much better functionality than screen, most of us that work with tmux have been using screen for a long time, and it is more comfortable for us to use ctrl-a than the default ctrl-b, which is finger-strechy. Thus the first thing I will do after installing tmux is to rebind the prefix to ctrl-a. That gives us the most handy way of swapping last two windows by typing ctrl-a ctrl-a.

Source-highlight for Matlab/octave

- - posted in homebrew, matlab, tips

I recently worked with Matlab a lot. When in console, sometimes I want to use less to quickly examine the file content, and I have already set it up such that it uses source-highlight to output colorful escape sequence to the console. However, source-highlight does not come with a syntax support for Matlab by default. Luckily, this post and this (in Chinese) provides a solution.

Fix (Ugly) Safari 7.0 Not Using Local Pac File

- - posted in networking, osx

I found that Safari in Mavericks is not using local proxy.pac at all. Turns out because of sandboxing, it will not allow reading file from local. A traditional solution is to turn on Web Sharing, and thus use HTTP to read the pac file such as http://localhost/proxy.pac.

However, this cannot be done that simple, since Apple removed Web Sharing from normal version of Mavericks. To turn on the web service (Apache), do this:

sudo apachectl start

Also, place the pac file under /Library/WebServer/Documents, which is the default Document Root of Apache.

Tom Fischer proposed another way to get around, however I don’t think it a good idea to mess around the system files.