Apurv Saxena's Blog

Matrix Multiplication: 3x3 and 3x1

2012-09-30T18:36:00.003+05:30

Formula: | a11 a12 a13 | | b1 | | a11*b1 + a12*b2 + a13*b3 | | a21 a22 a23 | x | b2 | = | a21*b1 + a22*b2 + a23*b3 | | a31 a32 a33 | | b3 | | a31*b1 + a32*b2 + a33*b3 | For arrays: | a11 a12 a13 | | a[0][0] a[0][1] a[0][2] | | a21 a22 a23 | = | a[1][0] a[1][1] a[1][2] | | a31 a32 a33 | |

Matrix Inverse - 3x3

2012-09-30T18:05:00.003+05:30

Operations of matrices of 3x3 are very common in day to day applications. Because the dimensions are already known, its better to avoid using a for-loop because of the extra computation involved in finding the subscript values. Following is a quick formula for the inverse of a 3x3 matrix (implemented as a 2D array). Formula The inverse of a 3x3 matrix: | a11 a12 a13 |-1

Forgotten rules of C/C++: Part 1

2012-08-11T19:46:00.001+05:30

Following is a list of important points people find very convenient to forget. This is the first article of a series · For bitwise operations, operand is promoted to "int" before evaluation. unsigned char I = 0x80; printf("%d", i<<1 nbsp="nbsp"> 256 · printf(5 + "intelligent"); => “ligent” Number specifies

Code Snippet - Summed Area Table

2012-06-28T16:29:00.003+05:30

SUMMED AREA TABLE Using the method described here, I have written the following code to calculate a summed area table. A sample image table of 5x5 dimensions has been assumed for simplicity. The code snippet and its results are given below. CODE // assumed height and width of the input table #define height 6 #define width 6 // input matrix - 5x5 long matrix[ height - 1][width -1] = {

Summed Area Table

2012-06-26T14:42:00.002+05:30

Definition Summed Area Table is both an algorithm and data structure used in reference with the concept of Integral images. SAT is a name used to refer to both the method and the result of conversion of an image to an integral image. SAT – The Algorithm Summed Area Table (or Integral Image) is an algorithm applied on a 2-dimensional array of elements. It’s a simple, single pass

Integral Image

2012-06-26T14:37:00.002+05:30

Definition An Integral image is one that is conducive to frequent summation operations. Any rectangular subset of such an image can be evaluated in constant time. Such an image is achieved by converting its pixel values to a SAT (summed area table) by simple interpolation of known pixel values. An Integral Image is defined as, I(x,y) = i(x,y) + I(x-1,y) + I(x,y-1) - I(x-1,y-1) Where, i(

How I Installed CUDA on my PC

2012-06-25T21:02:00.001+05:30

Platform: Windows 7 (32 bit) CUDA Hardware: None yet, will use simulator till then. 1 Prologue Before you start, get a clear idea about CUDA and its features from here. 2 Installation 2.1 Software setups Basic step is to download the latest SDK and to choose an appropriate Toolkit according to your hardware’s compute capability. Download links are given here.

CUDA Emulator

2012-06-25T20:57:00.000+05:30

The CUDA emulator is a software that duplicates (or emulates) the functions of a computer system with a CUDA-enabled card in a computer system with no such hardware, so that the emulated behavior closely resembles the behavior of the real system. This software package is mainly aimed to empower developers and students who do not have access to Nvidia GPU's. Initially, the CUDA

What is CUDA?

2012-06-25T20:15:00.001+05:30

The article serves as a prologue for beginners. Please note that this is a primer not a tutorial, tutorials will follow. CUDA (Compute Unified Device Architecture) is a parallel processing architecture that gives developers the ability to process their applications on CUDA-enabled processors. Basically it provides “us” the ability to process parallely, not just the CPU. The CPU and GPU are

Using UML in Projects

2011-02-16T11:27:00.000+05:30

Well the obvious question by any fresh student\developer is not how but WHY??? UML is used extensively in project development as a general programming practice, where you pictorially represent your entire project as a series of diagrams. What is UML? Seriously if you're still searching then I'd suggest Wikipedia. the most apt definition i found was: The Unified Modeling

IEEE - AIYEHUM 2011

2011-01-29T23:09:00.000+05:30

IEEE Bangalore is organizing AIYEHUM 2011, or The All India Young Engineers’ Humanitarian Challenge to encourage students to solve real world problems and promote their ideas by providing all necessary means to implement them. These projects will be judged on the basis of their impact on humanity and their creativity, and several other factors like sustainability and cost.

Sourceforge.net attacked!

2011-01-29T22:39:00.000+05:30

This was a direct attack to Open Source website sourceforge.net that hosts opensource projects made by anyone interested in making such projects. On Wednesday, the website reported exploit of several servers and fears compromise of user passwords. Hence all users have been asked to renew their passwords via the link: https://sourceforge.net/account/registration/recover.php Besides this, many

Google Summer of CodeTM 2011

2011-01-26T03:39:00.000+05:30

While surfing i came across this completely amazing concept by google, actually just another to add to their existing list of ideas. Eventually I also felt the need to promote this. Imagine being paid to express your coding abilities on open-source environments, i.e. to be paid stipends to work on open source programs. An excellent opportunity for college students to gain experience on

Exception Handling Basics

2010-11-19T23:17:00.002+05:30

Basics: Events are abnormal activities that occur during runtime. Errors are rather cataclysmic; there is no recovery or handling. Exceptions are the unwanted problems in a program that don’t cause irrecoverable damage. Exceptions are, in effect, just errors that can be handled by guessing their occurrence in a particular section of code. They are of two types, Checked

GO Programming Language

2010-11-16T17:45:00.000+05:30

GO is a systems programming language by Google.Inc. The official website http://golang.org/ describes this language as simple, fast, concurrent, safe, fun, open source and what not. So far it has not been developed for the Windows platform, so if interested, it means you need the good ol' Linux. GO is basically an OOPs based language that looks a lot like Java

Stack Template Class

2010-11-16T17:33:00.000+05:30

The stack template I made. Overflow conditions have been skipped as they practically dont occur on modern PC's. Please specify class T when you declare the object, for example for 'int', stack < type_name > stack_object_name; template < class T >class stack{ struct node { T data; struct node *next; }*top; public: stack() {

Queue Template

2010-10-26T16:43:00.004+05:30

The queue template I made. Overflow conditions have been skipped as they practically dont occur on modern PC's. Please specify class T when you declare the object, for example for 'int',queue < type_name > queue_object_name; template < class T >class queue{ struct node{ T data; struct node *next; &

Windows 7 and the Inevitble Headache of 32-bit C++

2010-09-19T23:34:00.000+05:30

Windows 7 is here, Windows 7 is the future, Windows 7 doesnt support my C++!!!!! TurboC is definitely functional but NOT COMPLETELY. This is alarming, but most conventional compilors and IDE's that worked on the traditional 16-bit environment will not work anymore, atleast not properly. The more advanced the OS becomes, the more detached it becomes from its roots, or so is the trend these

LinkLists in C++: Part 4

2010-08-26T21:29:00.000+05:30

Fourth in the series of Link-List funtions. /***************************************************/#include< iostream.h >#include< conio.h >#include< stdlib.h > struct node{ int info; node* next;}*start, *end, *t; void reverse(){ int n; t = start; while(t != NULL) { n++; t = t->next; } for(int i = 0;i <= n-3;i++) { t = start; while(t->next->next->next !=

LinkLists in C++: Part 3

2010-08-26T21:25:00.001+05:30

Third in the series of Link-List funtions. /***************************************************/#include< iostream.h >#include< conio.h >#include< stdlib.h > struct node{ int info; node* next;}*start, *end, *t; void listnode(){ t = start; cout <<"\nTHE CONTENTS ARE\n"; while(t != NULL) { cout <info < t = t->next; }} void count(){ t = start; int ctr = 0;

LinkLists in C++: Part 2

2010-08-26T21:19:00.002+05:30

Second in the series of Link-List funtions. /***************************************************/#include< iostream.h >#include< conio.h >#include< stdlib.h > struct node{ int info; node* next;}*start, *end, *t; void delnode(){ int ch; cout <<"\n1.DELETE IN THE BEGINNING."; cout <<"\n2.DELETE AT THE END."; cout <<"\n3.DELETE IN THE MIDDLE."; cout <<"\

LinkLists in C++: Part 1

2010-08-26T21:16:00.002+05:30

First in the series of Link-List funtions. /***************************************************/#include< iostream.h >#include< conio.h >#include< stdlib.h > struct node{ int info; node* next;}*start, *end, *t; void addnode(){ int ch; if(start == NULL) { start = new node; if(start == NULL) { cout <<"\nNOT ENOUGH MEMORY"; getch(); exit(0); } cout <<"\

A Nifty Trick...

2010-08-22T19:45:00.000+05:30

A trick is to make any PC shut down in a specified time with a horrifying message. No harm will be done of course. We will just make a small executable of ".exe" format for our mischief. The executable will work its magic only when clicked, so expect no "virus-action", but it can be easily disguised as some other program. Here are the steps: On your Desktop, Right click->New-&

Microsoft Robotics Developer Studio

2010-08-13T23:30:00.000+05:30

Robotics Developer Studio, or RDS, is an environment made by Microsoft to develop and test projects on robotics. This is a major step by Microsoft indeed, to promote hobbyists as well as professional developers. Using this Windows-based suite, not only can we write code for a robot, but simulate a virtual prototype in a real world scenario using the state-of-the-art simulation engine. Whats looks

What your C\C++ teachers didnt teach you...or forgot!!!

2010-08-11T23:21:00.000+05:30

Well their is no end to C\C++ and their never will be, simply because C++ can evolve to suit whats being demanded... Even this infinite syllabus has certain features that all of you should know. You might know most of this stuff but mind you many do not have that privilege. Level - C++ is NOT a "High Level Language", or atleast not a conventional HLL because of its heavy use of low level