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SEARCH KEYWORD -- Number theory

  Why 0.1+0.2 != 0.3

In programming languages such as JavaScript, c/c++, Java and Matlab, you will find that you will get unexpected result when doing float point calculation. For example, when calculating 0.1 + 0.1, you will not get 0.3: > 0.1 + 0.2 == 0.3 false > 0.1 + 0.2 0.30000000000000004 Don't be surprised of this result, this is the end result of IEEE 754 standard, float point number cannot be accurately represented according to IEEE 754 because: No enough memory is allocated for representing the num...

   float point,comparison,JavaScript     2014-11-19 05:32:46

  Eleven Equations True Computer Science Geeks Should (at Least Pretend to) Know

This idea is a complete rip off an article that appeared in Wired a little while ago and it got me thinking what would my list for Computer Science look like?  Plus I thought it might be a fun post and unlike the Wired list this one goes to eleven.  So here they are in no particular order: Binomial Coefficient The Binomial Coefficient equation generates Pascal’s Triangle and gives you the coefficients for the Binomial Theorem these ideas are often attributed to Pa...

   Algorithms,Computer science,Euler formula,Fermat     2011-11-29 08:42:50

  Set Theory in C++11

Have you ever felt the need to perform set theoretic operations on types? Not really? Me neither, but I thought it’s a fun thing to try out. So, if you ever feel the need of using type sets, C++11 makes it quite easy to do so. Especially variadic templates allow for a much more condensed syntax compared to type list constructs formerly used. (Disclaimer: This is rather a proof of concept, but maybe somebody comes up with a useful scenario.) Let’s start by d...

   C++,set theory,Math     2012-03-11 13:15:55

  Let 's write some front end codes

I've seen a lot of arguments that there is no much technical value writing web portal, I think that the vast majority of good programmers will try many different things. The low level development and machine learning are not the only technologies which are  full of wisdom and challenges, I wrote web site for a few years, it is difficult to say that this is my initial interest, although I touched on other technologies as well, I still feel building website is challenging. Front end developme...

   Front end development, JavaScript,CSS     2013-01-22 04:00:24

  How deep should unit test go?

There is a question on Stackoverflow which says "How deep are your unit tests?". It is asked by a guy named John Nolan. The question is not too new, but what catches me is the Best Answer given by Kent Beck, who is the creator of Extreme programming(XP) and Test Driven Development(TDD). Let's look at the question first. The thing I've found about TDD is that its takes time to get your tests set up and being naturally lazy I always want to write as little code as possible. The first thing I seem ...

   Unit test,TDD,XP     2012-09-03 10:11:27

  JavaScript finite state machine

Finite state machine is a very useful design model, it can be used to simulate many events in the world. In short, finite state machine has three features: Number of states is finite At any moment, one object can only be in one state In some condition, it will transfer from one state to another state In JavaScript, finite state machine can be applied in many places. For example, one menu element on a webpage. When the mouse hovers on the menu, the menu will show up, while the mouse moves away...

   JavaScript,Finite state machine,State     2013-09-02 11:00:57

  Scala, Patterns and The Perl Effect

He tried to understand that one concept for a couple of months before it made sense to him. Admittedly, partial functions are not intuitive for anyone who has been schooled in traditional programming, but still, looking at the problem he was trying to solve it seemed like James was required to expend too much effort relative to the simplicity of the problem (as he pointed out, now that he understands the concept it seems straightforward). He showed me the code, and it was basically a situa...

   Scala,Perl,Pattern,Partial function,Template     2011-12-21 09:25:41

  Lessons from the Trenches

I believe that making a game is part art and part science, so it's no wonder that managing a game project is also part art and part science. Clearly if it was all science then the industry would get a collective F for not having made any significant progress over the last decade - all one has to do is just glance at the published postmortems to see that the same patterns are repeated over and over.A game has to be fun, engaging, grab users in the first two minutes and also keep their a...

   Game,Trenches,Tips,Game design,pattern     2011-10-10 05:08:50

  Python: calculate lighter/darker RGB colors

Many times color palettes have lighter and darker variations of the same color. This may be used to convey relative importance, or for something as simple as a gradient. Usually the designer will specify both colors. However, if you have a site that needs to allow user configurable styling, you may not want to ask the user for two variations of the same color. Here is some Python code to take a single color in RGB, and output an artitrarily lighter or darker variation of the same color...

   Python,RGC color,Calucaltion lighter/darker     2012-02-13 05:29:22

  Only 4G can resolve the conflicts between China Telecom Carriers and WeChat ?

Why WeChat has made the three big Chinese telecom companies uncomfortable? Let's analyze from both technical and commercial levels. From a technical point of view, Mr. Huang, Dean of China Mobile Research Institute, described the impact of "always online service" applications like WeChat. Instead of using technical terms, we will explain in simple vivid phrases. First, mobile QQ, or WeChat, will have their own "request frequency". These requests are sent to the carrier network, to check the re...

   4G,WeChat,Telecom,China     2013-03-25 08:28:59

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