Maths Query

[T_k_w]

my fren, in the programming world, we call that reinventing the wheel. Why code yourself if someone else already done it? I have found many samples written by people using javascript.

 

U know lar, Uni first year, we have to learn c language mah... so after that i learn java(because of project) and after that vb (because of project), then sql, that time xml don't have fixed methods to manipulate, so must write own xml parser.

 

When I enter this company, they started following .net craze so I relearn vb.net, then c#.net(for embedded system), and now asp.net, ado.net and t-sql stored procedures, web services and ajax.

 

Now i read vb code can translate immediately into c#. Got attempted successfully translating simple java codes to c#.

 

So as you can see, my brain is alittle mixed up... my solution to most problem:" you got problem, why not just code it out and see what happens?"

 

abit the sian because, I am not that hard core and do FOSS stuff but windows stuff also got lots of interesting things to keep me occupied, like making the new .net dll communicate and work with old style dll.

Edited January 25, 2008 by T_k_w

[Redwood]

Extension of 1 - prove that (nk)!/((k!)^n) is an integer.

 

break up into parts,

(k!/k!)*[(k+1)(k+2)....(2k)/k!]*...*[((n-1)k+1)....nk]/k!

Edited January 25, 2008 by Redwood

[Redwood]

Can share:

What's the different between vb and vb.net? Is it more OOP?

[Requiemdk]

The idea is there though the last factor is a bit confusing to look at.

 

Another way is to interpret it as (n*k)!/((k!)(k!)...n times...(k!)), the number of ways of arranging n groups of k identical objects, again an integer. Cheapskate but effective combinatorial argument.

Edited January 25, 2008 by Requiemdk

[Redwood]

Seems that your major in is pure maths!!!

[Requiemdk]

That was a long time ago... Hoping to get back into it though after all these years returning to the books is like suddenly trying to take IPPT after not exercising for a year. Haha

[T_k_w]

talking about computing is abit off topic but here goes,

 

in the era of mid 199* there are 2 popular ways of programming windows application, 1 way is thru c++ using windows api( ugly beasts, i seen a couple of those. but very fast) not easy to develop.

 

that time bill gates has a dream that developing window application should be easy, so he come with the idea of extending the BASIC language to become visual basic aka vb and introduced the concept of visual studio where you can use a graphical interface to drag and drop components and then write minimal codes to link it up.

 

People(programmers wannabes) loved it. "programming" windows applications become super easy!

 

so it persisted for quite a while.

 

One day the people at SUN super dulan with programming with pointers, came up with the brilliant idea of designing a whole new langauge that hides(as in make inasessible) all pointer functions.

 

(wannabe) programmers at the microsoft vb camp say, "chey we don't deal with pointers a long time ago" and ignored the java development. They also secretly laugh at java for nothing good except making simple useless applets for kids while microsoft side already have very "bleeding" edge technology like COM, DCOM, ActiveX.

 

By the time microsoft wake up it's idea, SUN has used java to invade server applications and looks ready to replace those old IBM mainframes.

 

So they buay tahan and "intelligently copi*cough, cough*ed" java and make it c#(sharp)

and also they also don't want to tell those (wannabe) programmers to f**k off, so they "upgraded" vb to be one of the language supported by .NET.

 

Main difference between vb and vb.net,

vb is function based, vb.net is fully OOP, you can write your own class, supports polymorphism blah blah...

 

vb has ZERO inheritance, so a big vb project has hundreds of global variables floating around, no way of knowing which function is called by who. In short, very hard to scale, very hard to maintain.

 

Next, vb is a script language. In layman terms that mean SSSSLLLLLOOOOOWWWWWWWWW. Super slow because the computer read in 1 line of vb and execute then read next line and execute. There is no real multi-threading in the architecture so again, more slow as cannot fully utilise cpu. It is not event-based, so mostly work is done by polling(infinite loops) and i tell you infinite loops in the hands of (wannabe) programmers means from something as simple as memory leak to BSOD.

 

vb.net leverages on the .net platform so "tada" (most of) the problems i just listed have either disappeared or properly hidden under the digital rug.

 

with vb.net, the code is "compile" into IL(intermediate Language) aka human unreadable code. the compiler will do optimisation during compilation and executing IL is almost as good as machine code.

 

It also comes with .NET goodies like no more memory management problems, memory is allocated automatically and when the objects are out of their scope, they are auto garbage collected just like *cough*cough* java.

 

So there you have it, vb.net has class, support inheritance, is event-based, stable, fast, supports multi-threading but still has the same old goodness of classic vb such as drag and drop development in visual studio, intellisense late binding to microsoft COM objects.

 

okay, just abit of sideline, there 2 seperate vb technology you should know. vbscript is very tiny subset of classic vb(and some minor difference in writing) for scripting webpage, you can see it as microsoft's half-hearted attempt to defeat javascript.

 

VBA, if you used excel, you know when you open it will warn you if "macros" are present. You might even have created some of these macro yourself by using record feature.

 

The engine behind macro is VBA. visual basic for applications. It is like a cousin of classic vb where everything is sub-standard. Substandard debugging tools, substandard intelli-sense, limited access to functions, but you can do cool things with vba like use it to write pac-man that runs in excel.

Edited January 25, 2008 by T_k_w

[T_k_w]

Frankly speaking it is not worth to pick up vb.net. I learnt vb.net first before moving the c#. vb.net is SUPER laychey. Same thing in c# you use vb.net to write, you will easily need to type in 20% more code.

 

It is hard to keep track of when the loops end. for example in c#

 

if(a){

__if(b){

____if©{

______d;

____}

__}

}

 

using vb.net

 

IF a

__IF b

____IF c

_______d

____END IF

__END IF

END IF

 

Next, BASIC is really designed as a function-based language, now we are asking it to do OO stuff, the language itself becomes neither here nor there, and at times, confusing; especially when you want to write your own delegates and events to trigger some actions.

 

I was so pissed off by that, that I decide to bite the bullet and relearn everything in c#.

Edited January 25, 2008 by T_k_w

[Requiemdk]

Hi all,

 

How to prove the area of PQRS (rectangle) is 18x - 2x