Here’s an excerpt:

A New York City subway train holds 1,200 people. This blog was viewed about 5,700 times in 2011. If it were a NYC subway train, it would take about 5 trips to carry that many people.

Click here to see the complete report.

4 Programming Questions

Time: 2 hours

Languages: C/C++/Java

1. Longest sequence Problem and sorting it.
2. Northern and Western Skyline of buildings. Given x,y cordinates of diagonal of rectangle and the height of building.
3. A and B are arrays. B is generated from A. A is 1…N shuffled in some order.
   B[i]= number of items which are greater than A[i] for all indices>i
   example. N=4, B=[1 1 1 o]
   output A = [3 2 1 4]
4.  Finding a match for a man based on Help factor and proposal acceptance factor. Social networking kind of scenario and need to find a match with a max of  3 hops. Cannot propose immediate friends but can propose friends of friends. Friends can be male/female. but proposal can be only to females.

————————————————

SNAPSTICK
Time: 1 hour
Number of Questions : 9

Need to write Pseudocode for all 9 questions

1. 1. One line function to convert months(0-11) to quarter (0-3) . eg. mar-jun isin quarter 0. You cannot use if, switch, ternary, loop, etc.
2. Reverse a sentence word wise, eg. “This is cow” ==> “cow is this”
3. Image floodfill algorithm. given routines getcolor and setcolor
4. Given a number count number of bits that are ’1′
5. maxDepth of a tree given roots. Remember tree  and not binary tree.
6. in-place swapping in an array data using another array holding positions of the elements
7. getTop10() elements of a stream data at any instant . Also getkthlargest() data(here 10th largest i.e; k=10)
8. Dont remember
9. Dont remember
   ————————–
   PAYPAL
   5 Series questions like this and more coplex ones
   Q. 1,2,3,2,5,6,7,8,3,10,11,12,13,14,15,?some questions on cutting the rectangle in equal pieces1 logic question on telling lies and truth2 programming questions
   Q. Program to check if a n-digit number is Armstrong
   Q. simple switch-case program

————–
Strandlife
————
75 minutes

7 Questions:

1. REKHA * 4 = AHKER find number REKHA
2. 10 Green and 10 Blue balls . 5 balls drawn randomly(blindfolded). What is the probability that there are atleas 4 green balls.
3. Find numbers from 1 to 100 having odd number of factors
4. Euclideans algorithm for GCD
5. Two integer arrays A and B. Find for each x in A find the elements y in B such that |x-y| > k where k is an integer.
6. Pseudocode to find all the factors of a number n efficiently in space reduced.
7. Given a collection of strings <S1,….,Sn> and a query string q Determine if
a> q is equal to any string in collection
b> q is prefix of some string
c> q is substring of string

————-
Druva software

2 sections each of 30 mins

Section 1 : 30 questions  — Apti  and  C questions
Section 2 : 4 Questions — programming … very tough

Q1.
int X = 0;
F(int q)
{
int i =0;
for(i=0; i<q;i++)
{
f(i);
X++;
}
}

a> find recurrence relation of f(n) in terms of f(n-1)
b> represent f(n) arithmetically in terms of n

Q2.
Consider 2′s complement representation
a>
for(i=1; i<100;i++)
j &= i;

Represent j in terms j, may be i and some constant.

b> some obfuscated code… dont remember

Q3.
A question on moving instructions without using MOV

Q4. Code with maximum of 1 mistake. Need to find out that mistake
a> determing if number of a’s and b’s in both the strings are equal. the two strings contain only a and b
b> dont remember
c> something on stacks.. dont remember

More questions ….watch this space

The Blog-Health-o-Meter™ reads Fresher than ever.

Crunchy numbers

A Boeing 747-400 passenger jet can hold 416 passengers. This blog was viewed about 3,000 times in 2010. That’s about 7 full 747s.

In 2010, there were 13 new posts, growing the total archive of this blog to 18 posts. There were 20 pictures uploaded, taking up a total of 3mb. That’s about 2 pictures per month.

The busiest day of the year was December 3rd with 44 views. The most popular post that day was Computer Networking… Getting the basics right.

Where did they come from?

The top referring sites in 2010 were google.co.in, facebook.com, lmodules.com, cordless-homephone.info, and linkedin.com.

Some visitors came searching, mostly for whiteswami, top 10 algorithms of the 20th century, probability+scilab, gate cs essentials, and fingerprint core point code.

Attractions in 2010

These are the posts and pages that got the most views in 2010.

Computer Networking… Getting the basics right April 2010
2 comments

GATE CS Tips !! April 2010
9 comments

GATE IIT Admissions May 2010
2 comments

Fingerprint Recognition using DCT November 2009
13 comments

Fedora Post Installation Setting at IIT Bombay October 2009

Hi,
This is my first post after joining IIT. I had given more than a couple of interviews and finally landed up in IIT Bombay with specialisation in EE . I am a basically a comp science guy and had appeared for GATE in comp science. You’ll be wondering why did I choose EE rather than CS. I’ll tell you the whole build up to how we both(EE & I) chose each other. Also, I am more than glad that I have discovered that programming is not everything after joining EE and thus being myself and not following the herd.

I’ll start this with the  GATE preparations. Aspirants seeking guidelines for preparing GATE CS might like to look at my post “GATE CS Prepare”. I had done pretty well in the preparation of GATE and also featured in top 25 in 2 out of 4 tests that I appeared in GATEFORUM although I had not completed the syllabus. But I screwed up the GATE exam very badly and was able to score only 98.21 percentile(a pathetic rank of 747). The reasons of my failure were a plenty…..

1>I had prepared for GATE solving the previous year problems rather than reading the entire theory/content.  I had approached GATE with a problem oriented frame of mind.

2> Did not take Software Engg and Web seriously as it was newly introduced to the syllabus.

3> Had not completed even half of the compiler design.

4> Due to some external factors couldn’t prepare well in last 15 days right before the exam.

But, never the matter, i didn’t loose heart and applied for IITs and IISc for both MS(R) and M.Tech in hope that I ‘ll crack the test and interview if given a chance as some of my friends, whom I used to beat them in the preparatory test to GATE had secured ranks in double figure. Believing in myself was important at the time of applying. I had prepared well for Engg Maths and Discrete Maths and those were the strong points for me. I also had very good exposure of C Programming and had always done better in these areas than my counterparts.

IITB – CS [25th may'09]

After a few frustrating weeks, I indeed got my first call that too from IITB for a test & interview for M.Tech in Computer Science. There were around 400+ guys competing for it. The questions in the test were basically from Discrete Maths especially Graph Theory ang logic, Analytical skills, C Programming and one problem on computer networks.  There were in total 20 questioons divided into 4 areas- Maths, Analytical skills, Computer science, and C Programming. I cleared the test with  good scores. There were around 60-80 candidates selected for the next round. I outscored my friends who had a secured a rank of 100 odd. That was heartening to me. I had appeared in GATE with a desire to do my Masters in Priority 1 -Wireless communication orPriority 2- Artificial Intelligence, Before the tests we were introduced to various Assistantships as well as projects by the faculties of CS. My old love wireless did feature in a couple of projects and I didn’t find them very innovative. So, I decide upon NLP my second preference. We were supposed to give out our two preferences in order for the interviews. I luckily ended up getting selected for the interview on both the preferences which I had opted for namely, NLP and Machine Translation. Both of them somehow related to AI. I also had descent knowledge of NLP. One of the better books for NLP is “Speech and Language Processing” the one written by Jurafsky and Martin.

I waited for more than 5 hours for my turn to come…. and finally I was the last man to be inerviewed. I was interviewd by Prof Pushpak Bhatacharya. By the way, Prof. Pushpak is a stalwart in NLP and has developed wordnet libraries for many Indian languages and also heads the NLP group comprising of IIT-B, IIT-D, IIIT-H and a few more institutes. As soon as I entered, the first thing that was conveyed to me was that its a short interview and will be of not more than5 minutes. The interview generally last more than 20 to 40 minutes. I  was also told that I had scored heavily in the test. That gave me some confidence. But my confidence came crashing down when a question was asked on recurrence relation and I wasn’t able to solve. I was also asked a question on Generating function and again i failed miserably. Finally, I corrected a couple of mistakes committed in the written test as I was asked to. He did turn up with the question as what was my strong area and I replied confidently “NLP” and my interview ended abruptly after asking my job profile which was then a a developer/researcher in NLP domain at TRDDC….

I had screwed up my interview badly and facial expression was to say it all. Before leaving, Prof did try to console me by telling that the results are not dependent only on interview rather they’ll be also taking into account the GATE rank, test marks and profile. But, i knew i had lost.

After, a week the results were announced and as expected i could not make it.

MS(R) , SERC, IISc[9th june'09]

Next interview I was called for was from SERC , IISc . None of the areas mentioned in the list interested me but still I wanted to face the heat and went for the interview giving my preference as Databases which consisted of  XML databases, Query optimization, etc… although not being of my interest . This group is headed by Prof Haritsa and he is considered to be one of the top 3 in Databases in India. I appeared for the test and easily cleared it. There were 5 questiona nd time given was informally 20-25 minutes. The questions were related to Speed-distance, code snippet, Analytical skills. Out of 30 odd, they had selected 3.  Soon after the test my interview was taken and most of the answers that came from me were ” I don’t know” as they were specific to database ansd I hardly had any clue. Also, i didn’t like to do the guess work as it is not advisable during interview. Also, I did enjoy the interview as I didn’t have much interest in joining it. Finally, i was let off in a formal way although it could have been otherwise..worse[kicked.. no...hair-dryer treatment .... save me...]. But somehow, I escaped all these. But, one thing is sure , IISc has the best campus. I really loved the greenery there.

EE, IIT-Bombay [25th june'09]

While applying for IIT-Bombay, I had also written other department mentioning EE and hence, i got a call. I had applied for communications thinking that in case I get “Wireless” specialisation, I would grab it with both hands. I had applied only for communications as there was no point applying for streams which do not interest me much. I wrote the test and again cracked it. Only two comp science guys could clear it.. that too the other guy although had written GATE in CS but had a background in EE. There were 25 questions out of which any 20 were to be answered. There was almost equal number of questions in mathematics and electrical related. Surprisingly, I was one of the toppers in the test among communications guys although I didn’t know half of the question paper. I might have been lucky as there was no negative marking and I had guessed the electrical questions with some intuitions. Anyways, I thought this was my day. I was interviewed by a panel of 5 prof/asst. prof. I wasn’t asked any of the questions on electrical, rather I was asked a couple of linux commands, Mobile adhoc metwork scenarios, networking protocols ARP and my data mining. Data mining and Mobil ad hoc network questions came up due to its mention in my resume. Interview was pretty easy and cool. I was quite confident and answered everything to te point. Although, the interview took around half an hour , I never felt it took more than 5 minutes where as the interview I faced against Prof Pushpak I felt just the reverse(5 min interview as half an hour ). I was confident of my selection but you never know. i finally got the result on 7th July and I was assigned a Project  RA in Wireless and Sensor Networking under Professor Merchant. I finally talked to professor about the project and a couple of my friends and finally decide to give a shot.

Here in EE, I realized that Programming is an essential part and not everything. Infact, mathematical foundations are an essential armoury for computer science wich I wouldn’t have got, had I joined the CS dept.

But, the path to knowledge becomes more difficult as I also need to cope up with the foundations of EE and Maths at the same time. But, you aren’t well contented unless you do something which is hard to get.

More about GATE preparations and life in IIT will be coming … Keep watching this space

The future technologies built are already considering the various impacts on the environment and in some way everyone involved in these is also someway positively related to climate-change. Nowadays, for various projects government already carries out Environmental Impact Assessment(EIA) to ensure the well-being of planet. It’s indirectly for the well-being of us.

Paulo Coelho had aptly put it in words on his twitter: “Save the planet? Planet must be saying, “Save yourself idiots, I will be fine”

This area of research, “climate-change” is a big thing. Its more about “us than I”.  And, mind you this is not about publishing the number of papers, rather it is about what thought process(es) can really make giant leaps for mankind. One should not let publications drive his/her work. And if you really believe me, we do not have much time  as the situation might go out of hand.

I had been thinking for quite some time on how can I contribute in this very noble pursuit and finally jumped into it. In order to take any genuine strive for any concerned CCS, first we should have something to work on. This is what we call data. One could decide to collect data themselves or can use the data collected by other CCSs. Being so close to technology, I started collecting data myself. Its pretty trivial in a low scale deployment but the complexity increases as we go for high-scale deployment.  I have started with monitoring environment data using sensors, on a low-scale though. In the past one month, we have made a framework for collecting data. The term “data” here refers to “Environmental Parameters” like CO2, O2, CO, NO2, CH4, H2S, Temperature, Air Pressure, Relative Humidity, Wind Velocity, etc… For the very purpose of data collection, we at IIT Bombay/Hyderabad have started with Libelium Waspmote boards.

Environmental monitoring Process

To make a rational decision involving environment, we need to assess the various environmental parameters and accordingly act based on these various attributes. In our attempt to sense environment parameters, we have built a framework for sensing various environment parameters like temperature, pressure, humidity, oxygen, carbon dioxide, carbon monoxide, air contaminants, nitrogen dioxide, etc.  Now, the next stage would be interpreting the data. Interpretation of data would involve finding appropriate models for the various applications based on this framework. Finding trends or patterns is another important aspect of interpretation of data. Based on these findings the intended application would report and/or take appropriate action.

Data Collection:

Environmental Monitoring Architecture

This project is more inclined towards air pollution based applications but nevertheless it can be used as the base application for a number of applications. In this project, we have used small sensors for each corresponding environmental element and these sensors are attached to small electronic device, here waspmotes from Libelium. This sensing module is either powered by small battery or solar panel. A number of such sensing modules are deployed in areas such as forest, crowded city, industrial area, mines, power plants etc. depending upon the application. Each sensing module senses the various environmental parameters mentioned above. These sensing modules then send the collected data to the base station using multi-hop sensor networks and Radio Frequency technology. The base station then updates the database server and finally the web application enriches the experience of visualizing these data anywhere. Time scheduling and place location can be easily traced with the GPS/GPRS systems mounted on sensing modules.  It uses Xbee/Zigbee motes which uses license free band and this band are low power as well as short time transmissions. So there are no ill effects on surrounding human or any living organism. It also has social and economic benefits.

One of the biggest social benefits is that one is aware of the environments and thus we can together make our living better using the known information. For e.g., if based on data collection we find that the oxygen content is less than the normal content in a particular city, then government can take appropriate actions to plant more trees across the city. This enhances the way we live. An example of economical benefit would be making a service model with the cellular service providers for updating the customers with relevant data. One negative economic impact of this is that the motes are very costly and therefore, it becomes more important to develop cheap hardware/sensors.

sample_O2 concentration in %

Sensing environment as an EIA process.

The project can also be integrated into EIA process. This whole concept of environment monitoring can be effectively developed as a tool. For every new project which requires an EIA clearance can deploy the sensors and set up the tool to supply the relevant data. In this way, we can detect the immediate impact as well as predict the effects of the project on natural and social aspects. For e.g., if environmental gases concentration of nitrogen dioxide, sulphur dioxide increases in some project/plant vicinity then the forthcoming rain will be acidic in that area. And it can cause the land/soil infertile, infrastructure breakdown etc. The government/body can then take appropriate actions on behalf of farmers (social) and air quality (natural).

We also have all real-time data of project/plant surroundings so modelling impact prediction becomes very easy. Impact mitigating measures like environmental management plant (EMP), risk assessment report, rehabilitation plan can be implemented at a better level using this infrastructure and tools.

Some of the related/overlapping areas of research for the CCSs are:

1. Pervasive Computing(especially Context based)
2. Machine Learning/Pattern Recognition
3. Wireless Sensor Networking
4. ….and many more

Dear $Love,

I know this proposal is a form of communication and is of utmost importance and therefore would like the mutual information to be the maximum by using a discrete memoryless channel, here, Binary Erasure channel with epsilon–>0; because BEC in a sense is Error-free. In case there’s a erasure(confusion) , we shall sit together eliminate them and thus able to transform(using fourier transformations) ourselves for the better.  Although I am not a Comp Sci guy, but still I have been able to find the shortest path to our happiness and I would like to span this happiness(graph) to our entire life together. We could also hope for some novel genetic algorithms after you trigger “YES”(affirmative) command. To know more in detail about me use “man Rahul” and I am always there to help you “Rahul –help” . For the preview of our life you may like to use “Rahul_$love -v”(verbose mode). Hoping to see an affirmative acknowledgement before the timeout expires.

LUV

const LUV=”Rahul”

Many people ask me when is the best time to write a GATE CS exam. I naively tell them, once you are prepared . I think six months is a good time period for this exam. I wrote this exam after more than 2 and half years of my job experience. Aspirants who are in their 3rd/4th year of engineering curriculum might think they are at a better position to crack GATE. But, I would totally deny that. The only difference between working professional and engg. student is the amount of time they can allot to studies. The latter are in more advantageous position in this regard. This post can be taken as a set of guidelines for the GCSA. I indeed got some tips from the following documents:

1. “advice_by_GATE_AIR_8.doc”
2. ” Raj’s Collection” given in the doc “Books-GATE.doc”.
3. The “Analysis_CS.jpg” gives a good picture of how the marks are distributed.
4. Analysis_CS_2003_08 [The best resource before you start preparing] [To be uploaded..need to scan]

Analysus_CS_2003_08_PART1

Analysus_CS_2003_08_PART2

The above resources marked 1 and 2 are a good starting point for people who are not sure which books to read. The 3rd and 4th resource are analysis of GATE CS papers over the relevant years. The last two resources lets one also decide which subjects to skip in case one is short of time.The 4th resource, gives subject-wise and topic wise breakup of the distribution of marks over the years. Also, one need not cover the entire topics mentioned in the syllabus. Aspirants can as well leave out some of the subjects in which they are not interested or not proficient. Some of the subjects which are very essential for scoring high are: Discrete Maths, ToC, Digital Logic, Programming and Data Structures, Algorithms.

Solving the previous year papers almost covers the entire scoring area. So, it is always nice to solve GATE papers subject-wise.

I would particularly insist the GCSA to cover the Engg. Mathematics. The reason being, the questions asked in this area are pretty straightforward  and hence, quite easy. Most of the aspirants generally ignore this area and that is what becomes the deciding factor for good and great scores. Also try to know quicker ways of solving problems and that would give you more time to solve problems from other area.

I personally feel that the choice of books differs from one person to another and therefore, the list of books suggested can be omitted altogether in case one finds another book being superior/more suitable for their needs. My suggestions[Personal choice] for the references would be:

Engg Maths: Materials from Vani/ACE/Elite is very handy
Discrete Maths: Discrete mathematics & its applications, Kenneth H. Rosen
Graph Theory: Graph Theory, Narsingh Deo
ToC: Introduction to Automata Theory, Languages, and Computation, John E. Hopcroft, Jeffery D. Ullman
Compilers: Introduction to Compiler Design by Aho(first 7 chapters do not miss LALR parser)
Digital Logic: By Givon or Morris Mano. Both are equivalently good.
Computer Organization: By Hamacher
Programming & Data Structures: Book by Mark Allen Weiss is good + Relevant stuffs from http://cslibrary.stanford.edu/ is more than enough. Use wiki for any topic. Wiki is a very reliable source for this area.
Algorithms: Book by Cormen. + Use wiki for any algorithm. Wiki is a very reliable source for this area.
Operating Systems: Book by Galvin, Gagne, silberschatz is good except for Process synchronization. Use internet or Tanenbaum’s book for this particular topic.
Databases: Best book I feel is Navathe. Use Raghu Ramakrishna for Transactions & Concurrency control.
Computer Networks:Computer-Networks by Larry-L-Peterson, Bruce-S-Davie as well as book A top-down approach by Kurose & Ross are equivalently good.
Software Engg: I do not know any good resource as I skipped this subject. But I feel, Pankaj Jalote seems to serve the purpose.
Web/Html: Internet is the best resource for this. w3schools site for html is good.

One important suggestion: Kindly do not use books like Handa, GK etc. they are simply a waste of time. Gathering the concepts and knowing the tricks are the best ammunition for cracking GATE.

I’ll be updating this post with important topics in each subject in short time. For the time being .. I’ll just put the GATE 2010 CS Syllabus and will update it with scoring areas as an inline comment.

CS-Computer Science and Engineering

ENGINEERING MATHEMATICS

Mathematical Logic: Propositional Logic; First Order Logic.

Probability: Conditional Probability; Mean, Median, Mode and Standard Deviation; Random Variables; Distributions; uniform, normal, exponential, Poisson, Binomial.

Set Theory & Algebra: Sets; Relations; Functions; Groups; Partial Orders; Lattice; Boolean Algebra.

Combinatorics: Permutations; Combinations; Counting; Summation; generating functions; recurrence relations; asymptotics.

Graph Theory: Connectivity; spanning trees; Cut vertices & edges; covering; matching; independent sets; Colouring; Planarity; Isomorphism.

Linear Algebra: Algebra of matrices, determinants, systems of linear equations, Eigen values and Eigen vectors.

Numerical Methods: LU decomposition for systems of linear equations; numerical solutions of non-linear algebraic equations by Secant, Bisection and Newton-Raphson Methods; Numerical integration by trapezoidal and Simpson’s rules.

Calculus: Limit, Continuity & differentiability, Mean value Theorems, Theorems of integral calculus, evaluation of definite & improper integrals, Partial derivatives, Total derivatives, maxima & minima.

COMPUTER SCIENCE AND ENGINEERING

Theory of Computation: Regular languages and finite automata, Context free languages and Push-down automata, Recursively enumerable sets and Turing machines, Undecidability; NPcompleteness.

Digital Logic: Logic functions, Minimization, Design and synthesis of combinational and sequential circuits; Number representation and computer arithmetic (fixed and floating point).

Computer Organization and Architecture: Machine instructions and addressing modes, ALU and data-path, CPU control design, Memory interface, I/O interface (Interrupt and DMA mode), Instruction pipelining, Cache and main memory, Secondary storage.

Programming and Data Structures: Programming in C; Functions, Recursion, Parameter passing, Scope, Binding; Abstract data types, Arrays, Stacks, Queues, Linked Lists, Trees, Binary search trees, Binary heaps.

Algorithms: Analysis, Asymptotic notation, Notions of space and time complexity, Worst and average case analysis; Design: Greedy approach, Dynamic programming, Divide-and-conquer; Tree and graph traversals, Connected components, Spanning trees, Shortest paths; Hashing, Sorting, Searching.

Compiler Design: Lexical analysis, Parsing, Syntax directed translation, Runtime environments, Intermediate and target code generation, Basics of code optimization.

Operating System: Processes, Threads, Inter-process communication, Concurrency, Synchronization, Deadlock, CPU scheduling, Memory management and virtual memory, File systems, I/O systems, Protection and security.

Databases: ER-model, Relational model (relational algebra, tuple calculus), Database design (integrity constraints, normal forms), Query languages (SQL), File structures (sequential files, indexing, B and B+ trees), Transactions and concurrency control.

Computer Networks: ISO/OSI stack, LAN technologies (Ethernet, Token ring), Flow and error control techniques, Routing algorithms, Congestion control, TCP/UDP and sockets, IP(v4), Application layer protocols (icmp, dns, smtp, pop, ftp, http); Basic concepts of hubs, switches, gateways, and routers.

Taken From: http://moralstories.wordpress.com

The following code although not completely correct might help the intended viewers to have a crack at it. I intend to correct it in coming days[Short of time now ].

// Go Back N

//initialization
clear all;

m=3;
//Receiver_win_len=1;
Sender_win_len=2^m-1;
probFrameError=0;

RTT=3;
extraTimeout=5;
totalSumTime=0;

totalNumFrames=1000;

SendNextSeqNum=0;
RecvNextSeqNum=1;
sentFrames=0;
updatedSeqNum=0;
//oldSeqNum=1;

//
while(sentFrames<totalNumFrames)
[updatedSeqNum,lastAckSuccess]=SendWindowFrames(sentFrames+1,probFrameError,Sender_win_len,extraTimeout,RTT);
temp1=updatedSeqNum-sentFrames;
temp2=lastAckSuccess-sentFrames;
//printf("%d %d %d",updatedSeqNum,lastAckSuccess,sentFrames);
totalSumTime=totalSumTime+(temp1+temp2)*RTT*0.5;
if(temp1~=temp2)
totalSumTime=totalSumTime+extraTimeout;
end
sentFrames=min(updatedSeqNum,lastAckSuccess)-1;

end

pracValue=totalSumTime

theoreticalValue=totalNumFrames*RTT*0.5*(1+totalNumFrames*probFrameError/(1-probFrameError))//frame Transmission time = RTT*0.5


The function SendWindowFrames is as follows:

function [updatedSeqNum,lastAckSuccess] = SendWindowFrames(start,probFrameError,Sender_win_len,leftTimeout,RTT)
updatedSeqNum = start;
probAckError = 0;
lastAckSuccess=start-1;
timeout=leftTimeout;
endFrame=start+Sender_win_len-1;
for i=start:endFrame
if(leftTimeout<=0)
break;
end

pFrame=rand();
if(pFrame=probAckError)
lastAckSuccess=i;
leftTimeout=timeout;
else
leftTimeout=leftTimeout-RTT;
end
end
//retVal=min(lastAckSuccess,retVal)+1;
//updatedSeqNum=retVal;
endfunction