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• How to detect iPhone movement in space using accelerometer ?

  - by super_tomtom

  Hi ! I am trying to make an application that would detect what kind of shape you made with your iPhone using accelerometer. As an example, if you draw a circle with your hand holding the iPhone, the app would be able to redraw it on the screen. This could also work with squares, or even more complicated shapes. The only example of application I've seen doing such a thing is AirPaint (http://vimeo.com/2276713), but it doesn't seems to be able to do it in real time. My first try is to apply a low-pass filter on the X and Y parameters from the accelerometer, and to make a pointer move toward these values, proportionally to the size of the screen. But this is clearly not enought, I have a very low accuracy, and if I shake the device it also makes the pointer move... Any ideas about that ? Do you think accelerometer data is enought to do it ? Or should I consider using other data, such as the compass ? Thanks in advance !

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• problem with include in PHP

  - by EquinoX

  I have a php file called Route.php which is located on: /var/www/api/src/fra/custom/Action and the file I want to include is in: /var/www/api/src/fra/custom/ So what I have inside route php is an absolute path to the two php file I want to include: <?php include '/var/www/api/src/frapi/custom/myneighborlists.php'; include '/var/www/api/src/frapi/custom/mynodes.php'; ............ ........... ?> These two file has an array of large amount of size that I want to use in Route.php. When I do vardump($global) it just returns NULL. What am I missing here? UPDATE: I did an echo on the included file and it prints something, so therefore it is included.. however I can't get access that array... when I do a vardump on the array, it just returns NULL! I did add a global $myarray inside the function in which I want to access the array from the other php file Sample myneighborlists.php: <?php $myarray = array( 1=> array(3351=>179), 2=> array(3264=>172, 3471=>139), 3=> array(3467=>226), 4=> array(3309=>211, 3469=>227), 5=> array(3315=>364, 3316=>144, 3469=>153), 6=> array(3305=>273, 3309=>171), 7=> array(3267=>624, 3354=>465, 3424=>411, 3437=>632), 8=> array(3302=>655, 3467=>212), 9=> array(3305=>216, 3306=>148, 3465=>505), 10=> array(3271=>273, 3472=>254), 11=> array(3347=>273, 3468=>262), 12=> array(3310=>237, 3315=>237)); ?>

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• Joomla ImageBrowser Lightbox not working

  - by jmorhardt

  I've been using an image browser for Joomla called ImageBrowser. It's great - easy uploads, easy for clients to use, even handles zip file uploads. I have Joomla v. 1.5.15 installed and the newest version of this plugin as well on 3 or 4 of our sites with no fuss or issues. Recently, the ImageBrowser on one of our sites started acting strangely. It was as if the Lightbox effect that we should have disappeared completely. I compared the settings for the site to another and found they were identical. I couldn't find a solution in the documentation or forums. Here's the URL to look at: http://neda.us/photos?view=gallery&folder=BSU+12-5-09. You can compare that to another of our sites with the same plugin and settings at South Oak Floors dot COM. You should be able to click on a thumbnail and get a full size view of the image in a Lightbox. Any help much needed and much appreciated.

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• What is the most efficient way to handle points / small vectors in JavaScript?

  - by Chris

  Currently I'm creating an web based (= JavaScript) application thata is using a lot of "points" (= small, fixed size vectors). There are basically two obvious ways of representing them: var pointA = [ xValue, yValue ]; and var pointB = { x: xValue, y: yValue }; So translating my point a bit would look like: var pointAtrans = [ pointA[0] + 3, pointA[1] + 4 ]; var pointBtrans = { x: pointB.x + 3, pointB.y + 4 }; Both are easy to handle from a programmer point of view (the object variant is a bit more readable, especially as I'm mostly dealing with 2D data, seldom with 3D and hardly with 4D - but never more. It'll allways fit into x,y,z and w) But my question is now: What is the most efficient way from the language perspective - theoretically and in real implementations? What are the memory requirements? What are the setup costs of an array vs. an object? ... My target browsers are FireFox and the Webkit based ones (Chromium, Safari), but it wouldn't hurt to have a great (= fast) experience under IE and Opera as well...

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• JavaScript library not working in IE, can't see error information.

  - by Wolfy87

  Hi there. I have been writing a JavaScript library for a few weeks now and it works brilliantly in Firefox, Chrome and Safari. I had not tested it in IE until recently. I do not own a Windows box so after testing it on my friends and realising it wasnt working I started going over my code for things that could be causing it to break. So far I have found nothing. I could not find any descriptions of the errors in the browser while I was there either. So I wondered if anyone could run my test script in an IE browser (6, 7 or 8) and let me know any information they can find as to why it crashed. Please ignore any information saying it works in IE6, I put that up there after testing it through http://ipinfo.info/netrenderer/ I just assumed it was working because I could set transparency and size via my script and see it run in this tool. Here is the link to my GitHub repository: https://github.com/Wolfy87/Spark If you download it and run spark.html it will attempt to run all of my functions from the library. So if anyone could be kind enough to run it in IE and either let me know what errors they are getting and possibly how to fix them then I will be extreamly grateful. Thank you in advance. EDIT: Here is it's website http://sparkjs.co.uk/

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• Error loading font file using Imager::Font module in perl

  - by user211808

  use strict; use Imager; use Imager::Font; my $img = Imager->new(); my $file = "D:\\table.png"; $img->open(file=>$file) or die $img->errstr(); # Create smaller version my $thumb = $img->scale(scalefactor=>1.2); my $black = Imager::Color->new( 0, 0, 0 ); my $format; # Autostretch individual channels $thumb->filter(type=>'autolevels'); my $font_filename = "D:\\courbd.ttf"; my $font = Imager::Font->new(file=>$font_filename) or die "Cannot load $font_filename: ", Imager->errstr; for $format ( qw( png gif jpg tiff ppm ) ) { # Check if given format is supported if ($Imager::formats{$format}) { $file.="_low.$format"; print "Storing image as: $file\n"; $thumb->string(x => 50, y => 70, font =>$font, string => "Hello, World!", color => 'red', size => 30, aa => 1); $thumb->write(file=>$file) or die $thumb->errstr; } }

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• jQuery select image in div if image parent does't have a certain class.

  - by Alex

  Wordpress wraps images with captions in a div with a class of .wp-caption. I'm looking for a way to select images that don't have this div so I can wrap them in different div. (to keep a consistent border around all the images) <div class="blog-post-content"> <div id="attachment_220" class="wp-caption alignleft" style="width: 310px"> <a href="/somewhere/"><img class="size-medium wp-image-220" src="/path/to/image" alt="" width="300" height="280" /></a> <p class="wp-caption-text">Caption Text</p> </div> <p>This is the body of the post</p> </div> To test my selector, I'm just trying to add a green border. I can handle the .wrap() once the selector is working. The most promising of my attempts is: $('.blog-post-content img').parent('div:not(".wp-caption")').css('border', '2px solid green'); ... but no luck.

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• Stable/repeatable random sort (MySQL, Rails)

  - by Matt Rogish

  I'd like to paginate through a randomly sorted list of ActiveRecord models (rows from MySQL database). However, this randomization needs to persist on a per-session basis, so that other people that visit the website also receive a random, paginate-able list of records. Let's say there are enough entities (tens of thousands) that storing the randomly sorted ID values in either the session or a cookie is too large, so I must temporarily persist it in some other way (MySQL, file, etc.). Initially I thought I could create a function based on the session ID and the page ID (returning the object IDs for that page) however since the object ID values in MySQL are not sequential (there are gaps), that seemed to fall apart as I was poking at it. The nice thing is that it would require no/minimal storage but the downsides are that it is likely pretty complex to implement and probably CPU intensive. My feeling is I should create an intersection table, something like: random_sorts( sort_id, created_at, user_id NULL if guest) random_sort_items( sort_id, item_id, position ) And then simply store the 'sort_id' in the session. Then, I can paginate the random_sorts WHERE sort_id = n ORDER BY position LIMIT... as usual. Of course, I'd have to put some sort of a reaper in there to remove them after some period of inactivity (based on random_sorts.created_at). Unfortunately, I'd have to invalidate the sort as new objects were created (and/or old objects being removed, although deletion is very rare). And, as load increases the size/performance of this table (even properly indexed) drops. It seems like this ought to be a solved problem but I can't find any rails plugins that do this... Any ideas? Thanks!!

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• Many users, many cpus, no delays. Good for cloud?

  - by Eric

  I wish to set up a CPU-intensive time-important query service for users on the internet. A usage scenario is described below. Is cloud computing the right way to go for such an implementation? If so, what cloud vendor(s) cater to this type of application? I ask specifically, in terms of: 1) pricing 2) latency resulting from: - slow CPUs, instance creations, JIT compiles, etc.. - internal management and communication of processes inside the cloud (e.g. a queuing process and a calculation process) - communication between cloud and end user 3) ease of deployment A usage scenario I am expecting is: - A typical user sends a query (XML of size around 1K) once every 30 seconds on average. - Each query requires a numerical computation of average time 0.2 sec and max time 1 sec on a 1 GHz Pentium. The computation requires no data other than the query itself and is performed by the same piece of code each time. - The delay a user experiences between sending a query and receiving a response should be on average no more than 2 seconds and in general no more than 5 seconds. - A background save to a DB of the response should occur (not time critical) - There can be up to 30000 simultaneous users - i.e., on average 1000 queries a second, each requiring an average 0.2 sec calculation, so that would necessitate around 200 CPUs. Currently I'm look at GAE Java (for quicker deployment and less IT hassle) and EC2 (Speed and price optimization) as options. Where can I learn more about the right way to set ups such a system? past threads, different blogs, books, etc.. BTW, if my terminology is wrong or confusing, please let me know. I'd greatly appreciate any help.

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• Long primitive or AtomicLong for a counter?

  - by Rich

  Hi I have a need for a counter of type long with the following requirements/facts: Incrementing the counter should take as little time as possible. The counter will only be written to by one thread. Reading from the counter will be done in another thread. The counter will be incremented regularly (as much as a few thousand times per second), but will only be read once every five seconds. Precise accuracy isn't essential, only a rough idea of the size of the counter is good enough. The counter is never cleared, decremented. Based upon these requirements, how would you choose to implement your counter? As a simple long, as a volatile long or using an AtomicLong? Why? At the moment I have a volatile long but was wondering whether another approach would be better. I am also incrementing my long by doing ++counter as opposed to counter++. Is this really any more efficient (as I have been led to believe elsewhere) because there is no assignment being done? Thanks in advance Rich

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• Efficient and accurate way to compact and compare Python lists?

  - by daveslab

  Hi folks, I'm trying to a somewhat sophisticated diff between individual rows in two CSV files. I need to ensure that a row from one file does not appear in the other file, but I am given no guarantee of the order of the rows in either file. As a starting point, I've been trying to compare the hashes of the string representations of the rows (i.e. Python lists). For example: import csv hashes = [] for row in csv.reader(open('old.csv','rb')): hashes.append( hash(str(row)) ) for row in csv.reader(open('new.csv','rb')): if hash(str(row)) not in hashes: print 'Not found' But this is failing miserably. I am constrained by artificially imposed memory limits that I cannot change, and thusly I went with the hashes instead of storing and comparing the lists directly. Some of the files I am comparing can be hundreds of megabytes in size. Any ideas for a way to accurately compress Python lists so that they can be compared in terms of simple equality to other lists? I.e. a hashing system that actually works? Bonus points: why didn't the above method work?

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• CSS Sprite for images which have vertical as well as horizontal repeats

  - by Rachel

  I have four images, one of which has background repeat property in horizontal direction and three of which have background repeat in vertical direction. I have different CSS classes which currently uses this images as under: .sb_header_dropdown { background: url(images/shopping_dropdown_bg.gif) repeat-y top left; padding: 8px 3px 8px 15px; } .shopping_basket_dropdown .sb_body { background: url(images/shopping_dropdown_body_bg.png) repeat-y top left; margin: 0; padding: 5px 9px 5px 8px; position: relative; z-index: 99999; } .checkout_cart .co_header_left { background: url(images/bg.gif) repeat-x 0 -150px; overflow: hidden; padding-left: 3px; } .sb_dropdown_footer { background: url(images/shopping_dropdown_footer_bg.png) repeat-y top left; clear: both; height: 7px; font-size: 0; } So here am making 4 HTTP Request and I want to implement CSS Sprite for all 4 images such that I can reduce the number of HTTP Request from 4 to 1, also thing to keep in mind is that here we have background repeat for all 4 images, either on x-direction or on y-direction and so how should sprite be created and how it can be used in the CSS to reduce the number of HTTP request. I hope this question is clear.

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• Optimized 2D Tile Scrolling in OpenGL

  - by silicus

  Hello, I'm developing a 2D sidescrolling game and I need to optimize my tiling code to get a better frame rate. As of right now I'm using a texture atlas and 16x16 tiles for 480x320 screen resolution. The level scrolls in both directions, and is significantly larger than 1 screen (thousands of pixels). I use glTranslate for the actual scrolling. So far I've tried: Drawing only the on-screen tiles using glTriangles, 2 per square tile (too much overhead) Drawing the entire map as a Display List (great on a small level, way to slow on a large one) Partitioning the map into Display Lists half the size of the screen, then culling display lists (still slows down for 2-directional scrolling, overdraw is not efficient) Any advice is appreciated, but in particular I'm wondering: I've seen Vertex Arrays/VBOs suggested for this because they're dynamic. What's the best way to take advantage of this? If I simply keep 1 screen of vertices plus a bit of overdraw, I'd have to recopy the array every few frames to account for the change in relative coordinates (shift everything over and add the new rows/columns). If I use more overdraw this doesn't seem like a big win; it's like the half-screen display list idea. Does glScissor give any gain if used on a bunch of small tiles like this, be it a display list or a vertex array/VBO Would it be better just to build the level out of large textures and then use glScissor? Would losing the memory saving of tiling be an issue for mobile development if I do this (just curious, I'm currently on a PC)? This approach was mentioned here Thanks :)

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• Python: Sorting array with custom pattern

  - by Binka

  In my little project here I have sorted a list in decending order, however, my goal is to sort it in this custom pattern. (largest - smallest - next largest - next smallest -)etc. In java I was able to do this like this... My goal is to do the same thing but in python, except backwards. Any ideas on how to convert that last for loop that does the wackysort into python and make it go backwards? public static void wackySort(int[] nums){ //first, this simply sorts the array by ascending order. int sign = 0; int temp = 0; int temp2 = 0; for (int i = 0; i < nums.length; i++){ for (int j = 0; j < nums.length -1; j++){ if (nums[j] > nums[j+1]){ temp = nums[j]; nums[j] = nums[j+1]; nums[j+1] = temp; } } } //prepare for new array to actually do the wacky sort. System.out.println(); int firstPointer = 0; int secondPointer = nums.length -1; int[] newarray = new int[nums.length]; int size = nums.length; //for loop that increments by two taking second slot replacing the last (n-1) term for (int i = 0; i < nums.length -1; i+=2){ newarray[i] = nums[firstPointer++]; newarray[i+1] = nums[secondPointer--]; } //storing those values back in the nums array for (int i = 0; i < nums.length; i++){ nums[i] = newarray[i]; } }

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• How to load/save C++ class instance (using STL containers) to disk

  - by supert

  I have a C++ class representing a hierarchically organised data tree which is very large (~Gb, basically as large as I can get away with in memory). It uses an STL list to store information at each node plus iterators to other nodes. Each node has only one parent, but 0-10 children. Abstracted, it looks something like: struct node { public: node_list_iterator parent; // iterator to a single parent node double node_data_array[X]; map<int,node_list_iterator> children; // iterators to child nodes }; class strategy { private: list<node> tree; // hierarchically linked list of nodes struct some_other_data; public: void build(); // build the tree void save(); // save the tree from disk void load(); // load the tree from disk void use(); // use the tree }; I would like to implement the load() and save() to disk, and it should be fairly fast, however the obvious problems are: I don't know the size in advance; The data contains iterators, which are volatile; My ignorance of C++ is prodigious. Could anyone suggest a pure C++ solution please?

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• Margin-Top push outer div down

  - by Daniel Hertz

  Hello, I have a header div as the first element in my wrapper div, but when I add a top margin to a h1 inside the header div it pushes the entire header div down. I realize this happens whenever I apply a top margin to the first visible element on a page. Here is a sample of the css. Thanks! div#header{ width: 100%; background-color: #000; position: relative; } div#header h1{ text-align: center; width: 375px; height: 50px; margin: 0 auto; font-size: 220%; text-indent: -5000px; background: url('../../images/name_logo.png') no-repeat; } html part <div id="header"> <h1><a href="/home.php">Title</a></h1> <ul id="navbar">

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• Creating a OS X Cocoa App Web View in Xcode 5.0.1

  - by user1822824

  I created a HTML5 web app that I’m trying to wrap in a web view and submit to the Mac App Store. I’ve done the following: 1) Opened Xcode 5.0.1 and selected “Create a new Xcode project” 2) Under “OS X” I selected “Application” then I selected “Cocoa Application” then “Next” 3) I entered a “Product Name” and a “Company Identifier” then selected “Next” (I left all the other settings untouched) then “Create” 4) Under “General” “Deployment Info” “Deployment Target” I selected 10.6 — because I want the app to be compatible with all versions of OS X that support the Mac App Store 5) I clicked “MainMenu.xib” and selected “Window - My App” 6) From the “Object library” I drug the “Web View” object into my window and made it fill the window size 7) I saved my project and click the Play button in the upper left corner of Xcode The app tries to open but freezes. I don’t get an error in Xcode but it does open “main.m” and highlight “return NSApplicationMain(argc, argv);” in green and says “Thread 1: signal SIGABRT” I was hoping that someone could clarify why this isn’t working? And provide me with the last step to link the web view object? I searched Google and found tutorials for iOS and a few for OS X but for different versions of Xcode.

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• Detecting the axis of rotation from a pointcloud

  - by tfinniga

  I'm trying to auto-detect the axis of rotation on a 3d pointcloud. In other words, if I took a small 3d pointcloud, chose a single axis of rotation, and make several copies of the points at different rotation angles, then I get a larger pointcloud. The input to my algorithm is the larger pointcloud, and the desired output is the single axis of symmetry. And eventually I'm going to compute the correspondences between points that are rotations of each other. The size of the larger pointcloud is on the order of 100K points, and the number of rotational copies made is unknown. The rotation angles in my case have constant deltas, but don't necessarily span 360 degrees. For example, I might have 0, 20, 40, 60. Or I might have 0, 90, 180, 270. But I won't have 0, 13, 78, 212 (or if I do, I don't care to detect it). This seems like a computer vision problem, but I'm having trouble figuring out how to precisely find the axis. The input will generally be very clean, close to float accuracy.

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• Connect 4 C# (How to draw the grid)

  - by Matt Wilde

  I've worked out most of the code and have several game classes. The one bit I'm stuck on at the moment, it how to draw the actual Connect 4 grid. Can anyone tell me what's wrong with this for loop? I get no errors but the grid doesn't appear. I'm using C#. private void Drawgrid() { Brush b = Brushes.Black; Pen p = Pens.Black; for (int xCoor = XStart, col = 0; xCoor < XStart + ColMax * DiscSpace; xCoor += DiscSpace, col++) // x coordinate beginning; while the x coordinate is smaller than the max column size, times it by // the space between each disc and then add the x coord to the disc space in order to create a new circle. for (int yCoor = YStart, row = RowMax - 1; yCoor < YStart + RowMax * DiscScale; yCoor += DiscScale, row--) { switch (Grid.State[row, col]) { case GameGrid.Gridvalues.Red: b = Brushes.Red; break; case GameGrid.Gridvalues.Yellow: b = Brushes.Yellow; break; case GameGrid.Gridvalues.None: b = Brushes.Aqua; break; } MainDisplay.DrawEllipse(p, xCoor, yCoor, 50, 50); MainDisplay.FillEllipse(b, xCoor, yCoor, 50, 50); } Invalidate(); } Thanks.

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• CSS H4 hover style

  - by user1750613

  I tried many css from other places and stackoverflow, but somehow I can not make it done. I'm very new to css, and using Joomla and a template. I'm using custom.css folder for certain customizations on style. Here is I want to do: I want to style h4 when it is a link. For example, I'm creating a custom html module, have a list in the content. And in the content I'm giving each, h5 style, and a link to it to a certain page in the site. What I want to achieve is to have this list with color blue. And when mouse over-hover to have underline and still the same color. And when clicked back to the original position with no underline and no color change. (the same color in every situation, just underline when you are over it.) I tried these h5, h5 a, h5 a: hover, h5 .contentheading a, and so on... In one instance, it was working with : h5 { font-family: arial, sans-serif; font-size: 1.3em; font-weight: bold; } h5 a { color: #0088CC; } h5 a: hover { color: #0088CC; text-decoration: underline; } As I read I should use 'a' when the heading is a link. But now something is overriding it, I'm completely lost now. I see a:hover style in the inspection. I want to use this h5 in several content (in custom modules) when I want to style a content as a list to links. And I thought it will be practical to have one heading with a certain style so that I can use it with flexibility. Thanks a lot, any help will be great : )

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• C++ STL: How to iterate vector while requiring access to element and its index?

  - by Ashwin

  I frequently find myself requiring to iterate over STL vectors. While I am doing this I require access to both the vector element and its index. I used to do this as: typedef std::vector<Foo> FooVec; typedef FooVec::iterator FooVecIter; FooVec fooVec; int index = 0; for (FooVecIter i = fooVec.begin(); i != fooVec.end(); ++i, ++index) { Foo& foo = *i; if (foo.somethingIsTrue()) // True for most elements std::cout << index << ": " << foo << std::endl; } After discovering BOOST_FOREACH, I shortened this to: typedef std::vector<Foo> FooVec; FooVec fooVec; int index = -1; BOOST_FOREACH( Foo& foo, fooVec ) { ++index; if (foo.somethingIsTrue()) // True for most elements std::cout << index << ": " << foo << std::endl; } Is there a better or more elegant way to iterate over STL vectors when both reference to the vector element and its index is required? I am aware of the alternative: for (int i = 0; i < fooVec.size(); ++i) But I keep reading about how it is not a good practice to iterate over STL containers like this.

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• How to encrypt a RSAKey using another RSAKey?

  - by Tom Brito

  I know its not the usual thing to do. But the specification I'm implementing is discribed this way, and I cannot run out. I was trying to encrypt the modulus and exponent of the private key, but the following test code raises an exception because the byte array is 1 byte larger then the maximum allowed by RSA block: import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.NoSuchAlgorithmException; import java.security.NoSuchProviderException; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import javax.crypto.Cipher; import org.apache.commons.lang.ArrayUtils; public class TEST { public static KeyPair generateKeyPair() throws NoSuchAlgorithmException, NoSuchProviderException { KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA", "BC"); keyPairGenerator.initialize(1024); return keyPairGenerator.generateKeyPair(); } public static void main(String[] args) throws Exception { KeyPair keyPair = generateKeyPair(); RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate(); System.out.println("Priv modulus len = " + privateKey.getModulus().bitLength()); System.out.println("Priv exponent len = " + privateKey.getPrivateExponent().bitLength()); System.out.println("Priv modulus toByteArray len = " + privateKey.getModulus().toByteArray().length); byte[] byteArray = privateKey.getModulus().toByteArray(); // the byte at index 0 have no value (in every generation it is always zero) byteArray = ArrayUtils.subarray(byteArray, 1, byteArray.length); System.out.println("byteArray size: " + byteArray.length); RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic(); Cipher cipher = Cipher.getInstance("RSA", "BC"); cipher.init(Cipher.ENCRYPT_MODE, publicKey); byte[] encryptedBytes = cipher.doFinal(byteArray); System.out.println("Success!"); } } (obs. its just a test, i would never encrypt the private key with its pair public key) The byte array is 128 bytes, the exactly maximum allowed by a RSA block, so why the exception? And how to fix it?

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• Why does reusing arrays increase performance so significantly in c#?

  - by Willem

  In my code, I perform a large number of tasks, each requiring a large array of memory to temporarily store data. I have about 500 tasks. At the beginning of each task, I allocate memory for an array : double[] tempDoubleArray = new double[M]; M is a large number depending on the precise task, typically around 2000000. Now, I do some complex calculations to fill the array, and in the end I use the array to determine the result of this task. After that, the tempDoubleArray goes out of scope. Profiling reveals that the calls to construct the arrays are time consuming. So, I decide to try and reuse the array, by making it static and reusing it. It requires some additional juggling to figure out the minimum size of the array, requiring an extra pass through all tasks, but it works. Now, the program is much faster (from 80 sec to 22 sec for execution of all tasks). double[] tempDoubleArray = staticDoubleArray; However, I'm a bit in the dark of why precisely this works so well. Id say that in the original code, when the tempDoubleArray goes out of scope, it can be collected, so allocating a new array should not be that hard right? I ask this because understanding why it works might help me figuring out other ways to achieve the same effect, and because I would like to know in what cases allocation gives performance issues.

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• IE7 Debug Issue - Word Breaks in <li>

  - by JCHASE11

  Hello, I am having a very basic problem in IE7 that I cannot seem to fix. If you look at this page: http://vitaminjdesign.com/IAM/company/ you will notice that the vertical nav (ul id="leftcol") is displaying incorrectly in IE7. Each word appears on its own line. Here is my HTML /. CSS: <ul id="leftcol"> <li><a class="active" href="#">Company Overview</a></li> <li><a href="#">Why Choose Parker?</a></li> <li><a href="#">Testimonials</a></li> <li><a href="#">Financing Promotions</a></li> <li><a href="#">Licensing & Credentials</a></li> </ul> ul#leftcol{float:left; width:185px; position:relative; z-index:10;} ul#leftcol li{float:right; clear:right; margin-bottom:14px; list-style:none; list-style-image:none; text-align:right; line-height:1.3; } ul#leftcol li a{color:#505050; text-decoration:none; font-size:15px; float:right;} ul#leftcol li a.active,ul#leftcol li a:hover{color:#89b060;} Any ideas?

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• JavaScript: Is there a better way to retain your array but efficiently concat or replace items?

  - by Michael Mikowski

  I am looking for the best way to replace or add to elements of an array without deleting the original reference. Here is the set up: var a = [], b = [], c, i, obj; for ( i = 0; i < 100000; i++ ) { a[ i ] = i; b[ i ] = 10000 - i; } obj.data_list = a; Now we want to concatenate b INTO a without changing the reference to a, since it is used in obj.data_list. Here is one method: for ( i = 0; i < b.length; i++ ) { a.push( b[ i ] ); } This seems to be a somewhat terser and 8x (on V8) faster method: a.splice.apply( a, [ a.length, 0 ].concat( b ) ); I have found this useful when iterating over an "in-place" array and don't want to touch the elements as I go (a good practice). I start a new array (let's call it keep_list) with the initial arguments and then add the elements I wish to retain. Finally I use this apply method to quickly replace the truncated array: var keep_list = [ 0, 0 ]; for ( i = 0; i < a.length; i++ ){ if ( some_condition ){ keep_list.push( a[ i ] ); } // truncate array a.length = 0; // And replace contents a.splice.apply( a, keep_list ); There are a few problems with this solution: there is a max call stack size limit of around 50k on V8 I have not tested on other JS engines yet. This solution is a bit cryptic Has anyone found a better way?

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