引言

雪风是旧日本帝国在二战期间建造的一艘驱逐舰。她的一生充满传奇，作为战败国的一艘普通的驱逐舰，历经太平洋上大大小小超过十六次的海战而没有沉没，几无受损，被称作“奇跡の駆逐艦”、“呉の雪風 佐世保の時雨”、“不沈の航迹”等。关于雪风的文献很多：《激動の昭和 : 世界奇跡の駆逐艦 : 雪風》、《强运駆逐舰栄光の生涯》、《駆逐艦雪風―誇り高き不沈艦の生涯》等。 本文要讲的雪风的故事，从1938年开始，到1971年结束。

Introduction

Here is a not so short note (Rolling Update) for machine learning and artificial intelligience. Main concepts and some references are presented. This note is based on Wikipedia, Andrew Ng’s Lecture Notes CS229 of Standford, Machine Learning course of SJTU IEEE-yangyang, and Machine Learning Crash Course of Google.

Supervised Learning

In supervised learning, each example is a pair consisting of an input object (typically a vector) and a desired output value (also called the supervisory signal), like SVM, regression, decision trees, naive Bayes, etc. Classification means the output takes discrete values. Three common classification methods are Logistic Regression, Fisher Linear Discriminant Analysis and Nearest Neighbor Classification.

Introduction

Here is a not so short note (Rolling Update) for machine learning and artificial intelligience. Main concepts and some references are presented. This note is based on Wikipedia, Andrew Ng’s Lecture Notes CS229 of Standford, Machine Learning course of SJTU IEEE-yangyang, and Machine Learning Crash Course of Google.

The Learning Problem

• Input variables / features : $x^{(i)}$
• Target variable : $y^{(i)}$
• A training example: ($x^{(i)}$,$y^{(i)}$)
• A training set: {($x^{(i)}$,$y^{(i)}$); $i=1,2,...,m$}
• The space of input values: $X$
• The space of output values: $Y$

The goal is addressed as:

Introduction

Here is a not so short note (Rolling Update) for machine learning and artificial intelligience. Main concepts and some references are presented. This note is based on Wikipedia, Andrew Ng’s Lecture Notes CS229 of Standford, Machine Learning course of SJTU IEEE-yangyang, and Machine Learning Crash Course of Google.

Elementary concepts

What is machine learning?

Machine Learning is a scientific discipline that explores the construction and study of algorithms that can learn from data. Machine learning enables analysis of massive quantities of data. We all know “Machine”, i.e. computers or computer programs. Do you know what is “Learning”?

出云

日本领土陆地面积约37.79万平方公里，由北海道、本州、四国、九州等其他6,852个岛屿组成。看似国土狭小的日本，却拥有可怕的领海面积，约447万平方公里，超过其陆地面积十一倍。由于岛国的局限性，日本自古以来极其重视发展海军，并于第二次世界大战时期达到了巅峰。二战以后至今，日本作为战败国，曾经优秀的海军也随之衰落。截至目前日本海上自卫队的最大军舰是22DDH和24DDH。其中，DDH代表helicopter destroyer，即直升机驱逐舰。22和24分别指的是平成22年（2010年）和平成24年（2012年）完成防卫预算下拨。不过不要被它驱逐舰的名字迷惑了，DDH的体型相当于普通驱逐舰的3～5倍。所以日本其实是在玩文字游戏，其实它就是一艘直升机航空母舰。由于海上自卫队的性质，国际上是绝不允许日本建造巡洋舰、航空母舰等大型进攻型舰艇的，只好打打擦边球。强行命名为驱逐舰也可以看出日本海上自卫队的脸皮比航空母舰的甲板钢还要厚。有趣的是，

本文介绍如何使用SSH进行远程登录以及设置SSH免密码登录。

SSH简介

SSH(Secure Shell)是一个用于计算机间的远程登录会话和其他网络服务的加密网络安全协议，由互联网工程任务组 IETF（Internet Engineering Task Force）的网络工作小組（Network Working Group）所制定。相对于传统的网络服务，如FTP、 POP等， SSH协议避免了使用明文传输数据，帐号和口令，可以有效防止信息泄漏和中间人攻击，也能够防止DNS欺骗和IP欺骗。其具体工作原理本文不作详述。

使用SSH登录远程主机

• 首先判断是否安装SSH服务。打开Terminal试试：

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$ ssh localhost

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