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

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.

# Watch Review: Rodina R005GB

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So NOMOS has this awesome looking Bauhaus style watch: Tangente. Apparently everyone wants one, but not everyone wants to break their bank (\$2330 USD).

Luckily, we have an alternative here: Rodina series watches (or with Date).

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# Notes on Maximum Likelihood, Maximum a Posteriori and Naive Bayes

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Let $$\data$$ be a set of data generated from some distribution parameterized by $$\theta$$. We want to estimate the unknown parameter $$\theta$$. What we can do?

# Fix Mid 2009 MBP RAM Not Recognized Issue

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A few days ago, I encountered an issue which seems to be common among mid-2009 MBPs: one of the RAM (in slot 1) is not recognized anymore. Or, sometimes it is recognized, but after sleep and wake up, the computer freezes and impossible to recover but force power off.

# Replacing SATA Cable in Mid 2009 MBP

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Recently, my mid 2009 MBP (Model A1278) fails to recognize the hard drive. My first bet was another disk failure on me, but it was not the case. I took down the hard drive and put it to a mobile hard drive case and it can be read smoothly.

# My Octopress Blogging Flow

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After blogging with Octopress for a while, I have already gained some insights on it, and my publishing flow has been smoother. I think it is right time to share my flow as a reference.

# Sparse Image Reconstruction via L1-minimization

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 Original Minimum Energy Reconstruction Sparse Reconstruction

## Introduction

This is a follow up of the L1-minimization series. The previous two posts are:

# Sparse Signal Reconstruction via L1-minimization

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This is a follow-up of the previous post on applications of L1 minimization.

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# 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.

# Debugging AppleScript: Print to a File

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Debugging AppleScript is easy when you work with the script editor, simply use log to print out anything in the console. However, after you compiled it to an app, this cannot work anymore.

I find there are several ways to do it in this thread. The two approaches that work best for me are: