Clouding Computing Using GPUs

It seems that cloud computing and supercomputing have been in the conversion from massive CPUs to massive GPUs.

In the most recent Top500 Supercomputer list, although most supercomputers still use CPU and Linux, but one of them, the #5, uses ATI RadeonTM RV770 GPUs instead of x86 CPUs.

In a well-known blog post, How Will We Keep Supercomputing Super?, the author claims that due to the limitations stated by the Moore's law, the complexity of CPU makes it costly (in frontend complexity and power consumption) to combine more of them to achieve better performance. On the contrast, it is more technologically reasonable to combine GPUs, which contains more and simpler cores than CPUs.

It is also noticeable that the biggest GPU producer, Nvidia, recently launched their cloud computing product, RealityServer, on Amazon's cloud computing platform.

How to Write a Spelling Correction Program

This is an excellent article by Peter Norvig, a research director of Google.

Emacs — Tab vs. Space

To force Emacs to insert spaces instead of tabs when you press the TAB key:

M-x set-variable indent-tabs-mode nil

Or in your .emacs file:

(setq-default indent-tabs-mode nil)

C++ digraphs and additional keywords

[Original post]

A digraph is a keyword or combination of keys that lets you produce a character that is not available on all keyboards.

The digraph key combinations are:

Key Combination	Character Produced
<%	{
%>	}
<:	[
:>	]
%%	#

Additional keywords, valid in C++ programs only, are:

Keyword	Character Produced
bitand	&
and	&&
bitor	|
or	||
xor	^
compl	~
and_eq	&=
or_eq	|=
xor_eq	^=
not	!
not_eq	!=

To Make Firefox Display PDF on Mac OS X

On Windows, we can simply install Adobe Reader and Firefox will be able to find PDF plugin. However, on Mac OS X, we need to install the PDF Browser Plugin from Schubert|it.

VLHMM for Web Applications

It is glad to find that a WWW'09 paper cited my work on VLHMM (variable-length hidden Markov model). In this paper, Towards Context-Aware Search by Learning a Very Large Variable Length Hidden Markov Model from Search Logs, the authors propose to learn a very-large VLHMM for Web user behavior modeling. I also re-visited my old Web page on VLHMM.

Merge columns from two text files

pr -m -t -s\ file1 file2