Před pár týdny prezentoval Google na své konferenci Google I/O nový supertelefon HTC Evo 4G s operačním systémem Android. HTC Evo je naprosto výjimečný telefon, jako jeden z velice mála zvládá 4G připojení, má HDMI výstup, dvě kamery, velmi užitečný stojánek a mnoho dalších vychytávek. Pokud se o tomto telefonu chcete dozvědět více, čtěte recenzi na serveru www.svetandroida.cz.
Friday, June 11, 2010
Wednesday, June 2, 2010
Menší tip pro linuxáky
Každý správný linuxový geek už asi zažil, že ve Vimu zeditoval soubor, ale potom zjistil, že zrovna nemá práva pro uložení změn. No prostě opruz. Vždycky jsem si říkal, že to nějak jde, ale byl jsem tak trochu líný hledat ten správný příkaz. Až teď jsem na něj náhodou narazil na:
Příkaz je to opravdu jednoduchý:
:w !sudo tee %
Saturday, January 30, 2010
Web Browser JavaScript Test
The quality of web browsers is frequently discussed. Some favour Mozilla Firefox, some Opera, some Google Chrome, and many curse Internet Explorer. I'm not using Windows therefore IE is no concern of mine.
I met this web page today and I've decided to run all the diagnostic tests that are referenced there. These test include:
- V8 Benchmark Suite - version 5
- Acid3 Web Standarts Test
- Sunspider JavaScript Benchmark
- Dromaeo Performance Tests
Guess who the winner is. Not surprisingly, it's the youngest contestant - Google Chrome. Its V8 JavaScript engine is legen...wait for it...dary. Overall benchmark results are in the table. You can clearly see that Google Chrome dominates in all the JavaScript tests. There is a huge gap between Chrome and the second Firefox. The poorest did Opera. Acid3 test showed some problems in Firefox, all other browsers were flawless.
| Chrome | Firefox | Opera | |
|---|---|---|---|
| V8 | 2763 | 211 | 168 |
| Acid3 | 100/100 | 93/100 | 100/100 |
| Sunspider | 596.2 ms | 2909.4 ms | 4953.4 ms |
| Dromaeo | 209.83 runs/s | 44.79 runs/s | 28.43 runs/s |
Sunday, December 6, 2009
TOEFL registration
Recently, I decided to take the TOEFL exam. TOEFL is really useful if you want to get a position in a foreign company or if you want to study abroad. So I googled where I have to register: www.ets.org.
To sign up for the test you have to register at the web page at first place. So I tried to do it. I intentionally use a verb 'try' here because I failed. Why? The reason is a little strange architecture of the site. It doesn't allow anyone to have multiple user accounts. If you had registered some time ago you have to remember your login information! Write it down! They are not mailing any login information! Although the architecture of the web page seem really strange and inapt, there's a reason why ETS needs a web page with limited registration. The delay between two subsequent TOEFL exams is limited.
If you had registred and you don't remember you login information, the site provides some assistance to retrieve login information. Unfortunately, I found all these assistance procedures completely useless. I wasn't even able to figure out my user name. And, due to some lower/uppercase issues, I also failed to provide correct answer for the control question. After few wrong tries the site was blocking all other tries.
In case you have troubles, you can call a help desk. But it's an american phone number. I'm not really eager to call to the US! So my last chance was an e-mail. Fortunatelly, several emails and days later, ETS representatives sent me a new password and my forgotten user name. Really, write it down!
To sign up for the test you have to register at the web page at first place. So I tried to do it. I intentionally use a verb 'try' here because I failed. Why? The reason is a little strange architecture of the site. It doesn't allow anyone to have multiple user accounts. If you had registered some time ago you have to remember your login information! Write it down! They are not mailing any login information! Although the architecture of the web page seem really strange and inapt, there's a reason why ETS needs a web page with limited registration. The delay between two subsequent TOEFL exams is limited.
If you had registred and you don't remember you login information, the site provides some assistance to retrieve login information. Unfortunately, I found all these assistance procedures completely useless. I wasn't even able to figure out my user name. And, due to some lower/uppercase issues, I also failed to provide correct answer for the control question. After few wrong tries the site was blocking all other tries.
In case you have troubles, you can call a help desk. But it's an american phone number. I'm not really eager to call to the US! So my last chance was an e-mail. Fortunatelly, several emails and days later, ETS representatives sent me a new password and my forgotten user name. Really, write it down!
Friday, October 16, 2009
Python Challenge
Recently, I was writing about a convenient way of learning some Vim basics. Today I'm writing about a convenient way of learning Python. Python is an interpreted programming language, very useful for various computations, it's an extremely strong "calculator".
Learning a new programming language always brings some inconvenience. If you are an experienced programmer, you can usually figure out an algorithm solving the problem quickly. Then the problem is to realise how to write it down in the new language, and learning the syntax remains the biggest problem for you. I came across an interesting way of learning Python - Python Challenge. You can find it on the address http://www.pythonchallenge.com. The learning is done by a series of task you have to fulfil. A task is often in the form of a riddle and you have to write a simple program to solve it.
So, if you are interested in learning Python and/or enjoy solving riddles, try it!
Learning a new programming language always brings some inconvenience. If you are an experienced programmer, you can usually figure out an algorithm solving the problem quickly. Then the problem is to realise how to write it down in the new language, and learning the syntax remains the biggest problem for you. I came across an interesting way of learning Python - Python Challenge. You can find it on the address http://www.pythonchallenge.com. The learning is done by a series of task you have to fulfil. A task is often in the form of a riddle and you have to write a simple program to solve it.
So, if you are interested in learning Python and/or enjoy solving riddles, try it!
Friday, September 25, 2009
The Power of Vim
Every *nix programmer definetely knows Vim editor. Vim is an extremely strong editor. Although there are many GUI-based editors, I think Vim is superior. Once a programmer masters the efficient commands and command combinations, he be much faster in his work.
Although I know and use Vim several years, I don't know every command it provides. There are too many of them! Recently, I ran into a blog post mentioning a tutorial for Vim called 'vimtutor' which I hadn't know before. If you have Vim installed, try it!. Type 'vimtutor' and let it guide you through the tutorial. It shows only the basic commands, still, I think it's a great start to Vim.
Although I know and use Vim several years, I don't know every command it provides. There are too many of them! Recently, I ran into a blog post mentioning a tutorial for Vim called 'vimtutor' which I hadn't know before. If you have Vim installed, try it!. Type 'vimtutor' and let it guide you through the tutorial. It shows only the basic commands, still, I think it's a great start to Vim.
Monday, July 27, 2009
Precedence Constraint Posting (PCP) search strategy in Choco solvera
Using a PCP strategy in Choco constraint solver is rather problematic. The solver natively supports search strategies based on assigning a value to a variable. On the other hand PCP strategies are based on posting constraints. This is not natively supported. There are basically two way how to gain this functionality in Choco solver.
The first way is to extend the model with some extra constraints that can be bound to a variable, then AssignVar strategy with a specified variable and value selection can be used. To solve a scheduling problem a preceding constraint is suitable. The constraint has an extra boolean variable that specifies the precedence of given tasks. The search strategy then decides about these boolean variables first. Unfortunately, only several constraints has a variable that can be effectively used to create a PCP strategy.
Another way to use PCP strategy in Choco is much more complicated, the point is to implement an extension of abstract class AbstractLargeIntBranching that does what is required. Likewise, some useful selectors can be defined. The advantage of this approach is the generality, you can implement whichever strategy you like. I implemented some PCP strategies this way. A good pattern for this is CstrBranching class. It is a PCP implementation that can be found in svn sources in version 2.0.0 of the solver. The svn address is
The first way is to extend the model with some extra constraints that can be bound to a variable, then AssignVar strategy with a specified variable and value selection can be used. To solve a scheduling problem a preceding constraint is suitable. The constraint has an extra boolean variable that specifies the precedence of given tasks. The search strategy then decides about these boolean variables first. Unfortunately, only several constraints has a variable that can be effectively used to create a PCP strategy.
Another way to use PCP strategy in Choco is much more complicated, the point is to implement an extension of abstract class AbstractLargeIntBranching that does what is required. Likewise, some useful selectors can be defined. The advantage of this approach is the generality, you can implement whichever strategy you like. I implemented some PCP strategies this way. A good pattern for this is CstrBranching class. It is a PCP implementation that can be found in svn sources in version 2.0.0 of the solver. The svn address is
https://choco.svn.sourceforge.net/svnroot/choco.
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