给定任意单位轴q(q1,q2,q3)(向量),求向量p(x,y,z)(或点p)饶q旋转theta角度的变换后的新向量p'(或点p’)。
      使用旋转矩阵工具：构造旋转矩阵变换Trot,则变换后的新向量p’= p*Trot，其中，p’（x’,y’,z’,1）,p(x,y,z,1)为向量p’，p的4D齐次坐标表示。

          |t*q1*q1 + c,          t*q1*q2 + s*q3,      t*q1*q3 – s*q2,       0|
Trot =  |t*xq1*q2 – s*q3,    t*q2*q2 + c,           t*q2*q3 + s*q1,      0|
          |t*q1*q3 + s*q2,     t*q2*q3 – s*q1,      t*q3*q3 + c,           0|
          |0,                         0,                         0,                          1|

    其中c=cos(theta), s=sin(theta),t=1-c.

浓硫酸——没尝过，不知道…… 
稀硫酸——有点甜，特别酸，而且热呼呼的，很稠，舌头麻麻的…… 
浓盐酸——很酸，很辣，感觉舌头很凉，有刺痛感…… 
稀盐酸——感觉像维生素C，酸酸的辣辣的，过段时间会有一阵挥之不去的甘甜……（不
知道为什么哈……今天刚刚发现的） 
浓硝酸——没试过…… 
稀硝酸——非常酸，带有苦味和针扎似的辣味 
稀氢氧化钠——苦，辣，涩（恐怖感觉……）； 
无水乙醇——好奇怪的味道……不是很辣…… 
四氯化碳——说不出的恐怖感觉…… 
过氧化氢——辣，一开始很凉，一段时间后燥热……舌头上出现斑点状的白块，起斑点
的部分要痛几天…… 
乙醚……——好麻……舌头很涨…… 
Mg（OH）2——貌似没啥味道……  

Debian GNU/Linux 4.0 released

April 8th, 2007

The Debian Project is pleased to announce the official release of Debian GNU/Linux version 4.0, codenamed etch, after 21 months of constant development. Debian GNU/Linux is a free operating system which supports a total of eleven processor architectures and includes the KDE, GNOME and Xfce desktop environments. It also features cryptographic software and compatibility with the FHS v2.3 and software developed for version 3.1 of the LSB.

Using a now fully integrated installation process, Debian GNU/Linux 4.0 comes with out-of-the-box support for encrypted partitions. This release introduces a newly developed graphical frontend to the installation system supporting scripts using composed characters and complex languages; the installation system for Debian GNU/Linux has now been translated to 58 languages.

Also beginning with Debian GNU/Linux 4.0, the package management system has been improved regarding security and efficiency. Secure APT allows the verification of the integrity of packages downloaded from a mirror. Updated package indices won’t be downloaded in their entirety, but instead patched with smaller files containing only differences from earlier versions.

Debian GNU/Linux runs on computers ranging from palmtops and handheld systems to supercomputers, and on nearly everything in between. A total of eleven architectures are supported including: Sun SPARC (sparc), HP Alpha (alpha), Motorola/IBM PowerPC (powerpc), Intel IA-32 (i386) and IA-64 (ia64), HP PA-RISC (hppa), MIPS (mips, mipsel), ARM (arm), IBM S/390 (s390) and – newly introduced with Debian GNU/Linux 4.0 – AMD64 and Intel EM64T (amd64).

Debian GNU/Linux can be installed from various installation media such as DVDs, CDs, USB sticks and floppies, or from the network. GNOME is the default desktop environment and is contained on the first CD. The K Desktop Environment (KDE) and the Xfce desktop can be installed through two new alternative CD images. Also newly available with Debian GNU/Linux 4.0 are multi-arch CDs and DVDs supporting installation of multiple architectures from a single disc.

Debian GNU/Linux can be downloaded right now via bittorrent (the recommended way), jigdo or HTTP; see Debian GNU/Linux on CDs for further information. It will soon be available on DVD and CD-ROM from numerous vendors, too.

This release includes a number of updated software packages, such as the K Desktop Environment 3.5.5a (KDE), an updated version of the GNOME desktop environment 2.14, the Xfce 4.4 desktop environment, the GNUstep desktop 5.2, X.Org 7.1, OpenOffice.org 2.0.4a, GIMP 2.2.13, Iceweasel (an unbranded version of Mozilla Firefox 2.0.0.3), Icedove (an unbranded version of Mozilla Thunderbird 1.5), Iceape (an unbranded version of Mozilla Seamonkey 1.0.8), PostgreSQL 8.1.8, MySQL 5.0.32, GNU Compiler Collection 4.1.1, Linux kernel version 2.6.18, Apache 2.2.3, Samba 3.0.24, Python 2.4.4 and 2.5, Perl 5.8.8, PHP 4.4.4 and 5.2.0, Asterisk 1.2.13, and more than 18,000 other ready to use software packages.

Upgrades to Debian GNU/Linux 4.0 from the previous release, Debian GNU/Linux 3.1 codenamed sarge, are automatically handled by the aptitude package management tool for most configurations, and to a certain degree also by the apt-get package management tool. As always, Debian GNU/Linux systems can be upgraded quite painlessly, in place, without any forced downtime, but it is strongly recommended to read the release notes for possible issues. For detailed instructions about installing and upgrading Debian GNU/Linux, please see the release notes. Please note that the release notes will be further improved and translated to additional languages in the coming weeks.

About Debian

Debian GNU/Linux is a free operating system, developed by more than a thousand volunteers from all over the world who collaborate via the Internet. Debian’s dedication to Free Software, its non-profit nature, and its open development model make it unique among GNU/Linux distributions.

The Debian project’s key strengths are its volunteer base, its dedication to the Debian Social Contract, and its commitment to provide the best operating system possible. Debian 4.0 is another important step in that direction.

Contact Information

For further information, please visit the Debian web pages at http://www.debian.org/ or send mail to <press@debian.org>.