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• Implementation of ECC in Java

  - by Rookie_22

  While trying to encrypt a given input using Elliptic Curve Cryptography in Java I'm using the following algorithms for generating the cipher and the key: KeyPairGenerator g = KeyPairGenerator.getInstance("ECDSA"); Cipher cipher = Cipher.getInstance("ECIES"); Now as expected, the cipher isn't accepting the keys generated by the ECDSA algorithm. I get the error as - must be passed IE key. I searched for the ciphers being supported by these 2 methods here: http://java.sun.com/javase/6/docs/technotes/guides/security/StandardNames.html#Cipher Unfortunately no else algo is supported for ECC. Has anyone used ECC generated keys to encrypt/decrypt an input? Which algo should I use for both so that they don't clash with each other?

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• Is it possible to find the KNN for a node that is *IN* the KD-tree?

  - by Stephen

  Hi there, Trying to create a KNN search using a KD-tree. I can form the KD-tree fine (or at least, I believe I can!). My problem is that I am searching to find the closest 2 neighbours to every point in a list of points. So, is there a method to find the K nearest neighbours to a point using a KD tree even if the point is actually IN the tree, or do I need to construct a seperate KD tree for each point, leaving out the point that I wish to search for? My implementation language is C++, but I am more looking for either an algorithm or general help, thanks! Thanks, Stephen

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• image focus calculation

  - by Oren Mazor

  Hi folks, I'm trying to develop an image focusing algorithm for some test automation work. I've chosen to use AForge.net, since it seems like a nice mature .net friendly system. Unfortunately, I can't seem to find information on building autofocus algorithms from scratch, so I've given it my best try: take image. apply sobel edge detection filter, which generates a greyscale edge outline. generate a histogram and save the standard dev. move camera one step closer to subject and take another picture. if the standard dev is smaller than previous one, we're getting more in focus. otherwise, we've past the optimal distance to be taking pictures. is there a better way? update: HUGE flaw in this, by the way. as I get past the optimal focus point, my "image in focus" value continues growing. you'd expect a parabolic-ish function looking at distance/focus-value, but in reality you get something that's more logarithmic

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• Robotics Simulator

  - by Arkapravo

  Which is the best robotics simulator ? Player Project (simulator + control interface) Microsoft Robotics Studio (simulator + control interface) KiKS (in Matlab, only for Khepera) MobotSim (for point like robots ) ROS (I have only heard about it) URBI (also, only heard about it) Any other As of now, I am just looking to get simple simulations of Potential Field method, Bug Algorithms, A* Algorithm etc ! This article gives a number of such softwares etc, however I was looking for a first hand view from fellow stackoverflowers. Anyone who has worked with any other software etc is most welcome to share his/her experience !

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• How do I run JUnit from NetBeans?

  - by FarmBoy

  I've been trying to understand how to start writing and running JUnit tests. When I'm reading this article: http://junit.sourceforge.net/doc/testinfected/testing.htm I get the the middle of the page and they write, "JUnit comes with a graphical interface to run tests. Type the name of your test class in the field at the top of the window. Press the Run button." I don't know how to launch this program. I don't even know which package it is in, or how you run a library class from an IDE. Being stuck, I tried this NetBeans tutorial: http://www.netbeans.org/kb/docs/java/junit-intro.html It seemed to be going OK, but then I noticed that the menu options for this tutorial for testing a Java Class Library are different from those for a regular Java application, or for a Java Web App. So the instructions in this tutorial don't apply generally. I'm using NetBeans 6.7, and I've imported JUnit 4.5 into the libraries folder. What would be the normal way to run JUnit, after having written the tests? The JUnit FAQ describes the process from the Console, and I'm willing to do that if that is what is typical, but given all that I can do inside netbeans, it seems hard to believe that there isn't an easier way. Thanks much. EDIT: If I right-click on the project and select "Test" the output is: init: deps-jar: compile: compile-test: test-report: test: BUILD SUCCESSFUL (total time: 0 seconds) This doesn't strike me as the desired output of a test, especially since this doesn't change whether the test condition is true or not. Any ideas?

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• async handler deleted by the wrong thread in django

  - by user3480706

  I'm run this algorithm in my django application.when i run several time from my GUI django local server will stopped and i got this error Exception RuntimeError: RuntimeError('main thread is not in main loop',) in ignored Tcl_AsyncDelete: async handler deleted by the wrong thread Aborted (core dumped) code print "Learning the sin function" network =MLP.MLP(2,10,1) samples = np.zeros(2000, dtype=[('x', float, 1), ('y', float, 1)]) samples['x'] = np.linspace(-5,5,2000) samples['y'] = np.sin(samples['x']) #samples['y'] = np.linspace(-4,4,2500) for i in range(100000): n = np.random.randint(samples.size) network.propagate_forward(samples['x'][n]) network.propagate_backward(samples['y'][n]) plt.figure(figsize=(10,5)) # Draw real function x = samples['x'] y = samples['y'] #x=np.linspace(-6.0,7.0,50) plt.plot(x,y,color='b',lw=1) samples1 = np.zeros(2000, dtype=[('x1', float, 1), ('y1', float, 1)]) samples1['x1'] = np.linspace(-4,4,2000) samples1['y1'] = np.sin(samples1['x1']) # Draw network approximated function for i in range(samples1.size): samples1['y1'][i] = network.propagate_forward(samples1['x1'][i]) plt.plot(samples1['x1'],samples1['y1'],color='r',lw=3) plt.axis([-2,2,-2,2]) plt.show() plt.close() return HttpResponseRedirect('/charts/charts') how can i fix this error ?need a quick help

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• UI design in flash games

  - by anon

  This question is more UI/Design-ish than hard-core programming is. Background: I've been coding in VIM/C++/OpenGL for a long time. I've come to realize that this (VIM/C++/OpenGL) isn't the way to learn about programming fancy/cool-looking/futuristic UIs; and that the design of such UIs belongs more so in the artistic/designer world of Flash. Anyway, I currently have a machine with MacOSX. What software should I install? What book should I read to learn about the artistic/design side of these futuristic UIs? [It's okay if the tools to design them are mouse clicking + graphical rather than coding based]. Question: what software packages + books to read to learn about creating fancy-looking / futuristic UIs in flash? Thanks! EDIT: PS these questions seem to get closed frequently. If you're going to vote to close for "duplicate question"; atleast provide a link to the question (with an answer).

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• On Windows, how does console window ownership work?

  - by shroudednight

  When a console application is started from another console application, how does console ownership work? I see four possibilities: The second application inherits the console from the first application for its lifetime, with the console returning to the original owner on exit. Each application has its own console. Windows then somehow merges the content of the two into what the "console" visible to the user The second application get a handle to the console that belongs to the first application. The console is placed into shared memory and both applications have equal "ownership" It's quite possible that I missed something and none of these four options adequately describe what Windows does with its consoles. If the answer is close to option 4. My follow-up question is which of the two processes is responsible for managing the window? (Handling graphical updates when the screen needs to be refreshed / redrawn, etc) A concrete example: Run CMD. Then, using CMD, run [console application]. The [console application] will write to what appears to be the same console window that CMD was using.

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• Recompile a x86 code with LLVM to some faster one x86

  - by osgx

  Hello Is it possible to run LLVM compiler with input of x86 32bit code? There is a huge algorithm which I have no source code and I want to make it run faster on the same hardware. Can I translate it from x86 back to x86 with optimizations. This Code runs a long time, so I want to do static recompilation of it. Also, I can do a runtime profile of it and give to LLVM hints, which branches are more probable. The original Code is written for x86, and uses no SSE/MMX/SSE2. After recompilation It has a chances to use x86_64 and/or SSE3. Also, The code will be regenerated in more optimal way to hardware decoder. Thanks.

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• What is the relaxation condition in graph theory

  - by windopal

  Hi, I'm trying to understand the main concepts of graph theory and the algorithms within it. Most algorithms seem to contain a "Relaxation Condition" I'm unsure about what this is. Could some one explain it to me please. An example of this is dijkstras algorithm, here is the pseudo-code. 1 function Dijkstra(Graph, source): 2 for each vertex v in Graph: // Initializations 3 dist[v] := infinity // Unknown distance function from source to v 4 previous[v] := undefined // Previous node in optimal path from source 5 dist[source] := 0 // Distance from source to source 6 Q := the set of all nodes in Graph // All nodes in the graph are unoptimized - thus are in Q 7 while Q is not empty: // The main loop 8 u := vertex in Q with smallest dist[] 9 if dist[u] = infinity: 10 break // all remaining vertices are inaccessible from source 11 remove u from Q 12 for each neighbor v of u: // where v has not yet been removed from Q. 13 alt := dist[u] + dist_between(u, v) 14 if alt < dist[v]: // Relax (u,v,a) 15 dist[v] := alt 16 previous[v] := u 17 return dist[] Thanks

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• retrieve cobol s9(2) COMP onto C variable

  - by Pablo Cazallas

  Hi, I need to retrieve data from a COBOL variable of the type: "PIC S9(2) COMP" onto a C variable of the type "int". It's stored using two bytes of a string, so I receive it as a couple of chars. I know COBOL stores decimal data onto a "S9(2) COMP" in binary format, so It would be a great help letting me know any algorithm or way to convert it safely. Any kind of help & suggestion will be welcome. Thanks in advance and regards, Pablo.

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• For a primary key of an integral type, why is it important to avoid gaps ?

  - by Jacques René Mesrine

  I am generating a surrogate key for a table & due to my hi/lo algorithm, everytime you reboot/restart the machine, gaps may appear. T1: current hi = 10000000 (sequence being dished out .. 1 to 100) Assume that current sequence is 10000050 T2: restart system. T3: System gives out the next_hi as 10000100 (sequence being dished out now ranges from 101 to 200) T4: Next request for a key returns 100001001 From a primary key or indexing internals perspective, why is it important that there be no gaps in the sequences ? I'm asking this for a deeper understanding of mysql specifically. Thanks

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• Distance by sea calculator, intermediate coordinates?

  - by Lucian2k

  How do I calculate distance between 2 coordinates by sea? I also want to be able to draw a route between the two coordinates. Only solution I found so far is to split a map into pixels, identify each pixel as LAND or SEA and then try to find the path using A* algorithm. Then transform pixels to relative coordinates. There are some software packages I could buy but none have online extensions. A service that calculates distances between sea ports and plots the path on a map is searates.com

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• Java - sorted stack

  - by msr

  Hello, I need a sorted stack. I mean, the element removed from the stack must be the one with great priority. Stack dimension varies a lot (becomes bigger very fast). I need also to search elements in that stack. Does Java give some good implementation for this? What class or algorithm do you suggest for this? I'm using a PriorityQueue right now which I consider reasonable except for searching, so Im wondering if I can use something better. Thanks in advance!

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• Using a priority queue in Java

  - by Bharat

  Forgive me if this is a tried question, but I'm having a little difficulty figuring it out. I currently have a class Node, and each 'node' is a square in a maze. I'm trying to implement the A* algorithm, so each of these nodes will have an f-cost (int) data member inside of it. I was wondering if there's a way that I can create a priority queue of these nodes, and set up the f-cost variable as the comparator? I've looked at examples online, but all I can find are String priority queues. Can I implement Comparator for the Node class? Would this allow me to access the data member stored inside it? Many Thanks!

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• Extracting pure content / text from HTML Pages by excluding navigation and chrome content

  - by Ankur Gupta

  Hi, I am crawling news websites and want to extract News Title, News Abstract (First Paragraph), etc I plugged into the webkit parser code to easily navigate webpage as a tree. To eliminate navigation and other non news content I take the text version of the article (minus the html tags, webkit provides api for the same). Then I run the diff algorithm comparing various article's text from same website this results in similar text being eliminated. This gives me content minus the common navigation content etc. Despite the above approach I am still getting quite some junk in my final text. This results in incorrect News Abstract being extracted. The error rate is 5 in 10 article i.e. 50%. Error as in Can you Suggest an alternative strategy for extraction of pure content, Would/Can learning Natural Language rocessing help in extracting correct abstract from these articles ? How would you approach the above problem ?. Are these any research papers on the same ?. Regards Ankur Gupta

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• Java Generics Type Safety warning with recursive Hashmap

  - by GC

  Hi, I'm using a recursive tree of hashmaps, specifically Hashmap map where Object is a reference to another Hashmap and so on. This will be passed around a recursive algorithm: foo(String filename, Hashmap<String, Object> map) { //some stuff here for (Entry<String, Object> entry : map.entrySet()) { //type warning that must be suppressed foo(entry.getKey(), (HashMap<String, Object>)entry.getValue()); } } I know for sure Object is of type Hashmap<String, Object> but am irritated that I have to suppress the warning using @SuppressWarnings("unchecked"). I'll be satisfied with a solution that does either a assert(/*entry.getValue() is of type HashMap<String, Object>*/) or throws an exception when it isn't. I went down the Generics route for compile type safety and if I suppress the warning then it defeats the purpose. Thank you for your comments, ksb

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• Compute average distance from point to line segment and line segment to line segment

  - by Fred

  Hi everyone, I'm searching for an algorithm to calculate the average distance between a point and a line segment in 3D. So given two points A(x1, y1, z1) and B(x2, y2, z2) that represent line segment AB, and a third point C(x3, y3, z3), what is the average distance between each point on AB to point C? I'm also interested in the average distance between two line segments. So given segment AB and CD, what is the average distance from each point on AB to the closest point on CD? I haven't had any luck with the web searches I've tried, so any suggestions would be appreciated. Thanks.

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• Flash to PHP base64 encode/decode

  - by Gus

  I'm using AS3 to base64 encode a JPG and pass it to Javascript. I'm attempting to use AJAX to pass that base64 encoded string to PHP and have PHP decode it. (I know I could send it back to Flash and Flash could decode it and send it to PHP, but I'm trying to eliminate the need for Flash on the decoding end). It appears that AS3's encodeToBase64String() function and and PHP's base64_decode() function do not use the same algorithm, as PHP evaluates it as a base64 encoded object, but does not seem to output it properly. Is there a way to rectify this problem? Note: Please no posts about not needing Javascript. Javascript is a necessary step for reasons not detailed here.

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• what is the best way to generate fake data for classification problem ?

  - by Berkay

  i'm working on a project and i have a subset of user's key-stroke time data.This means that the user makes n attempts and i will use these recorded attempt time data in various kinds of classification algorithms for future user attempts to verify that the login process is done by the user or some another person. (Simply i can say that this is biometrics) I have 3 different times of the user login attempt process, ofcourse this is subset of the infinite data. until now it is an easy classification problem, i decided to use WEKA but as far as i understand i have to create some fake data to feed the classification algorithm. can i use some optimization algorithms ? or is there any way to create this fake data to get min false positives ? Thanks

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• using Excel VBA, given the daily price of 50 stocks, choose 10 stocks such that they have the minumu

  - by correl

  The high-level goal is to choose 10 stocks that have the lowest correlation among one another, out of a pool of 50, so that I can have a well-diversified portfolio. I have managed to write some VBA macro to download the past 3 years of daily price data from Yahoo finance, and then compute the 50x50 correlation matrix (using the Correl function), using the daily close as the data. What I have tried so far is just some local-maximum heuristic: - For the two stocks that have the highest correlation with each other, remove one of them. Between the two, remove the one that has the higher average correlation with all the other stocks. - When I remove a stock from the pool, I just delete the correponding row and column, to give a smaller matrix. - Repeat until I have just 10 stocks remaining (a 10x10 matrix). I was wondering if there is some algorithm that already solves such a problem and gives the optimum solution?

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• Android - need UI help/advice

  - by Donal Rafferty

  I have been working on Android for the past couple of months getting to know how various components work. One area I am completely lacking in knowledge is any sort of User Interface or graphical interface creation. As an excercise I have been asked to break down the HTC call screen into what components it contains and rebuild as close as possible. Here is a picture of the HTC call screen: From my understanding the above UI has a custom title bar where "Meteor" and the call time appears. Then the main image in the middle block along with a text view showing the called party, in this case "Voice Mail" and the number. The bottom is then a custom view maybe with three custom buttons used within it. Would I be correct in my above assumptions? So the parts I should look into start programming are a custom title bar and a custom view with three custom buttons to place at the bottom? What layout would be reccomended? I hope this question is seen as relative to Stack Overflow, if it is not then I will delete it. Thanks in advance

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• Limit a program's execution time in C (Monte Carlo technique)

  - by rrs90

  I am working on a project which has no determined algorithm to solve using C language. I am Using Monte Carlo technique for solving that problem. And the number of random guesses I want to limit to the execution time specified by the user. This means I want to make full use of the execution time limit defined by the user (as a command line argument) to make as many random iterations as possible. Can I check the execution time elapsed so far for a loop condition. Eg: for(trials=0;execution_time P.S. I am using code blocks 10.05 for coding and GNU compiler.

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• Polynomial division overloading operator

  - by Vlad

  Ok. here's the operations i successfully code so far thank's to your help: Adittion: polinom operator+(const polinom& P) const { polinom Result; constIter i = poly.begin(), j = P.poly.begin(); while (i != poly.end() && j != P.poly.end()) { //logic while both iterators are valid if (i->pow > j->pow) { //if the current term's degree of the first polynomial is bigger Result.insert(i->coef, i->pow); i++; } else if (j->pow > i->pow) { // if the other polynomial's term degree is bigger Result.insert(j->coef, j->pow); j++; } else { // if both are equal Result.insert(i->coef + j->coef, i->pow); i++; j++; } } //handle the remaining items in each list //note: at least one will be equal to end(), but that loop will simply be skipped while (i != poly.end()) { Result.insert(i->coef, i->pow); ++i; } while (j != P.poly.end()) { Result.insert(j->coef, j->pow); ++j; } return Result; } Subtraction: polinom operator-(const polinom& P) const //fixed prototype re. const-correctness { polinom Result; constIter i = poly.begin(), j = P.poly.begin(); while (i != poly.end() && j != P.poly.end()) { //logic while both iterators are valid if (i->pow > j->pow) { //if the current term's degree of the first polynomial is bigger Result.insert(-(i->coef), i->pow); i++; } else if (j->pow > i->pow) { // if the other polynomial's term degree is bigger Result.insert(-(j->coef), j->pow); j++; } else { // if both are equal Result.insert(i->coef - j->coef, i->pow); i++; j++; } } //handle the remaining items in each list //note: at least one will be equal to end(), but that loop will simply be skipped while (i != poly.end()) { Result.insert(i->coef, i->pow); ++i; } while (j != P.poly.end()) { Result.insert(j->coef, j->pow); ++j; } return Result; } Multiplication: polinom operator*(const polinom& P) const { polinom Result; constIter i, j, lastItem = Result.poly.end(); Iter it1, it2, first, last; int nr_matches; for (i = poly.begin() ; i != poly.end(); i++) { for (j = P.poly.begin(); j != P.poly.end(); j++) Result.insert(i->coef * j->coef, i->pow + j->pow); } Result.poly.sort(SortDescending()); lastItem--; while (true) { nr_matches = 0; for (it1 = Result.poly.begin(); it1 != lastItem; it1++) { first = it1; last = it1; first++; for (it2 = first; it2 != Result.poly.end(); it2++) { if (it2->pow == it1->pow) { it1->coef += it2->coef; nr_matches++; } } nr_matches++; do { last++; nr_matches--; } while (nr_matches != 0); Result.poly.erase(first, last); } if (nr_matches == 0) break; } return Result; } Division(Edited): polinom operator/(const polinom& P) { polinom Result, temp; Iter i = poly.begin(); constIter j = P.poly.begin(); if (poly.size() < 2) { if (i->pow >= j->pow) { Result.insert(i->coef, i->pow - j->pow); *this = *this - Result; } } else { while (true) { if (i->pow >= j->pow) { Result.insert(i->coef, i->pow - j->pow); temp = Result * P; *this = *this - temp; } else break; } } return Result; } The first three are working correctly but division doesn't as it seems the program is in a infinite loop. Update Because no one seems to understand how i thought the algorithm, i'll explain: If the dividend contains only one term, we simply insert the quotient in Result, then we multiply it with the divisor ans subtract it from the first polynomial which stores the remainder. If the polynomial we do this until the second polynomial( P in this case) becomes bigger. I think this algorithm is called long division, isn't it? So based on these, can anyone help me with overloading the / operator correctly for my class? Thanks!

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• Sorting a file with 55K rows and varying Columns

  - by Prasad

  Hi I want to find a programmatic solution using C++. I have a 900 files each of 27MB size. (just to inform about the enormity ). Each file has 55K rows and Varying columns. But the header indicates the columns I want to sort the rows in an order w.r.t to a Column Value. I wrote the sorting algorithm for this (definitely my newbie attempts, you may say). This algorithm is working for few numbers, but fails for larger numbers. Here is the code for the same: basic functions I defined to use inside the main code: int getNumberOfColumns(const string& aline) { int ncols=0; istringstream ss(aline); string s1; while(ss>>s1) ncols++; return ncols; } vector<string> getWordsFromSentence(const string& aline) { vector<string>words; istringstream ss(aline); string tstr; while(ss>>tstr) words.push_back(tstr); return words; } bool findColumnName(vector<string> vs, const string& colName) { vector<string>::iterator it = find(vs.begin(), vs.end(), colName); if ( it != vs.end()) return true; else return false; } int getIndexForColumnName(vector<string> vs, const string& colName) { if ( !findColumnName(vs,colName) ) return -1; else { vector<string>::iterator it = find(vs.begin(), vs.end(), colName); return it - vs.begin(); } } ////////// I like the Recurssive functions - I tried to create a recursive function ///here. This worked for small values , say 20 rows. But for 55K - core dumps void sort2D(vector<string>vn, vector<string> &srt, int columnIndex) { vector<double> pVals; for ( int i = 0; i < vn.size(); i++) { vector<string>meancols = getWordsFromSentence(vn[i]); pVals.push_back(stringToDouble(meancols[columnIndex])); } srt.push_back(vn[max_element(pVals.begin(), pVals.end())-pVals.begin()]); if (vn.size() > 1 ) { vn.erase(vn.begin()+(max_element(pVals.begin(), pVals.end())-pVals.begin()) ); vector<string> vn2 = vn; //cout<<srt[srt.size() -1 ]<<endl; sort2D(vn2 , srt, columnIndex); } } Now the main code: for ( int i = 0; i < TissueNames.size() -1; i++) { for ( int j = i+1; j < TissueNames.size(); j++) { //string fname = path+"/gse7307_Female_rma"+TissueNames[i]+"_"+TissueNames[j]+".txt"; //string fname2 = sortpath2+"/gse7307_Female_rma"+TissueNames[i]+"_"+TissueNames[j]+"Sorted.txt"; string fname = path+"/gse7307_Male_rma"+TissueNames[i]+"_"+TissueNames[j]+".txt"; string fname2 = sortpath2+"/gse7307_Male_rma"+TissueNames[i]+"_"+TissueNames[j]+"4Columns.txt"; //vector<string>AllLinesInFile; BioInputStream fin(fname); string aline; getline(fin,aline); replace (aline.begin(), aline.end(), '"',' '); string headerline = aline; vector<string> header = getWordsFromSentence(aline); int pindex = getIndexForColumnName(header,"p-raw"); int xcindex = getIndexForColumnName(header,"xC"); int xeindex = getIndexForColumnName(header,"xE"); int prbindex = getIndexForColumnName(header,"X"); string newheaderline = "X\txC\txE\tp-raw"; BioOutputStream fsrt(fname2); fsrt<<newheaderline<<endl; int newpindex=3; while ( getline(fin, aline) ){ replace (aline.begin(), aline.end(), '"',' '); istringstream ss2(aline); string tstr; ss2>>tstr; tstr = ss2.str().substr(tstr.length()+1); vector<string> words = getWordsFromSentence(tstr); string values = words[prbindex]+"\t"+words[xcindex]+"\t"+words[xeindex]+"\t"+words[pindex]; AllLinesInFile.push_back(values); } vector<string>SortedLines; sort2D(AllLinesInFile, SortedLines,newpindex); for ( int si = 0; si < SortedLines.size(); si++) fsrt<<SortedLines[si]<<endl; cout<<"["<<i<<","<<j<<"] = "<<SortedLines.size()<<endl; } } can some one suggest me a better way of doing this? why it is failing for larger values. ? The primary function of interest for this query is Sort2D function. thanks for the time and patience. prasad.

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