坑人的联通宽带

家里有一个Raspberry Pi，想弄来做个小的网页服务器玩玩。用lighttpd搭了个测试页面，内网可以正常访问。

路由器已经刷成dd-wrt，设置了DMZ主机和端口映射。听说国内已经禁了普通家庭用户的80端口，也特地设置了不一样的端口号。。。。但是就是无法从外网访问。

然后注意到dd-wrt上显示的WAN IP和www.ip138.com上显示的不一样。。。。。。

原来家里的IP不是外网IP，中间还隔着一个联通宽带的二级ISP。所以无法远程访问内网主机。

联通太坑了。。。以前用电信的光纤宽带好像还是可以的。

参考：这里

Mavericks!

Helped upgrade a friend's 2011 MacBook Pro to Mavericks.

Found a nice tutorial on macworld. It indicates 2 options for the upgrade installation:

- use createinstallmedia OR

- use disk utility

The first option never works, it always returns an error when creating a bootable drive:

Failed to start erase of disk due to error (-9999, 0). 

A error occurred erasing the disk.

The second one works like a charm :)

Two useful links:

http://www.macworld.com/article/2056561/how-to-make-a-bootable-mavericks-install-drive.html


http://eric.gavaletz.com/2013/10/making-os-x-mavericks-usb-installer.html

Latex script

If you are tired of making multiple clicks in TexWorks everytime just to get one .tex compiled into a PDF, here is a quick windows script. Note that bibtex works with the .aux file.

 echo %~f0  
 pdfLatex sample.tex  
 bibtex sample.aux  
 pdfLatex sample.tex  
 pdfLatex sample.tex  
 echo "Press any key to close (or your own message here)"  
 pause > nul  
 del *.aux  
 del *.bbl  
 del *.log  
 del *.blg  
 del *.out  
 sample.pdf  

P.S. JabRef is nice bib management tool on Windows.

MathJax Test

$$ x_{1,2} = \frac{-b \pm \sqrt{b^2-4ac}}{2b}. $$ Here is the link that shows how to use MathJax to show \( \LaTeX \) typesetting on Blogspot. Well written. :) 

Try a linear inverted pendulum dynamic equation:

\[ \ddot{y}=\frac{g}{z_c}-\frac{1}{m z_c}u_r \]

Note that enclosing math in single $'s does not work in the default setting for MathJax.

By default, use "\(\backslash(\)" and "\(\backslash)\)" for inline math and double dollar signs or "\(\backslash[\)" and "\(\backslash]\)" for displayed math.

Examples: inline equations: \((y+\sqrt z)^{-1}\) and \( \sin^2 x^2 \). And displayed equations
$$\frac{2}{3}$$
\[ {H}(q)\ddot{q} + C(q,\dot{q})\dot{q}+G(q)\dot{q} = S^T \tau + J^T f \]

One downside is, you will not see the typesetting result in the edit (compose) mode. It will show up after you press publish or update button.

6:30 a.m.

Such a beautiful morning. Hope it's also the beginning of a productive day.

A good day starts with a home-made guacamole, with extra amount of onions. :)