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  • Notes from a short presentation on NodeJs

    - by Aligned
    Originally posted on: http://geekswithblogs.net/Aligned/archive/2014/05/30/notes-from-a-short-presentation-on-nodejs.aspxI volunteered myself to give a short 30 minute presentation at a work lunch and learn on NodeJs. With my limited experience I see using Node as a great tool for build process improvement, scaffolding with yeoman, and running tests with Karma. I haven’t looked into using as a full server or development stack. I guess I’m too stuck on IIS and Visual Studio :-). Here are my notes, that aren’t very well formatted, but I wanted to share it anyways. What is it? "Node.js is a platform built on Chrome's JavaScript runtime for easily building fast, scalable network applications. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, perfect for data-intensive real-time applications that run across distributed devices." Why should you be interested? another popular tool that can help you get the job done you can use the command prompt! can be run at build or release time to automate tasks What are some uses? https://www.npmjs.org/ - NuGet for Node packages http://bower.io/ - NuGet for UI JavaScript libraries (jQuery, Bootstrap, Angular, etc) http://yeoman.io/ "Our workflow is comprised of three tools for improving your productivity and satisfaction when building a web app: yo (the scaffolding tool), grunt (the build tool) and bower (for package management)." -> yeoman asks which components you want alternative - http://joakimbeng.eu01.aws.af.cm/slush-replacing-yeoman-with-gulp/ https://www.npmjs.org/package/generator-cg-angular - phantom js, less, // git is needed for bower http://git-scm.com/ run installer in Windows before you can use bower // select Run Git from the Windows Command Prompt in the installer // requires a reboot http://stackoverflow.com/questions/20069297/bower-git-not-in-the-path-error npm install -g git npm install -g yo npm install -g generator-cg-angular mkdir myapp cd myapp yo cg-angular npm install -g bower npm install -g grunt-cli yo bower grunt serve grunt test grunt build // there are many generators (generator-angular) is another one // I like the Nuget HotTowel-Angular from John Papa myself // needed IIS Node for Express -> prompt from WebMatrix Karma bat to startup Karma - see below image compression - https://www.npmjs.org/search?q=optimize+images, https://github.com/heldr/node-smushit - do it from the command line LESS compiling js and css combine and minification at build with Gulp for requireJS apps quick lightweight HTTP server - "Express" Build pipeline with Grunt or Gulp http://www.johnpapa.net/gulp-and-grunt-at-anglebrackets/ Gulp is the newer and improved over Grunt. Supposed to be easier to use, but Grunt is more established. https://github.com/johnpapa/ng-demos/tree/master/grunt-gulp https://github.com/assetgraph/assetgraph-builder Does a lot of the minimizing, combining, image optimization etc using Node. Looks interesting.... http://nodejs.org http://nodeschool.io/ http://sub.watchmecode.net/getting-started-with-nodejs-installing-and-writing-your-first-code/ https://stormpath.com/blog/build-a-killer-node-dot-js-client-for-your-rest-plus-json-api/ https://codio.com/ http://www.hanselman.com/blog/ItsJustASoftwareIssueEdgejsBringsNodeAndNETTogetherOnThreePlatforms.aspx run unit tests - Karma in msBuild karma-start.bat @echo off cd %~dp0\.. REM 604800 is to make sure we only update once every 7 days call npm install --cache-min 604800 -g grunt-cli call npm install --cache-min 604800 call npm install --cache-min 604800 -g karma-cli karma start UnitTests\karma.conf.js REM karma start UnitTests\karma.conf.js --single-run REM see karma-start.bat and karam.config.js REM jsHint comes from Nuget

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  • 2D SAT Collision Detection not working when using certain polygons

    - by sFuller
    My SAT algorithm falsely reports that collision is occurring when using certain polygons. I believe this happens when using a polygon that does not contain a right angle. Here is a simple diagram of what is going wrong: Here is the problematic code: std::vector<vec2> axesB = polygonB->GetAxes(); //loop over axes B for(int i = 0; i < axesB.size(); i++) { float minA,minB,maxA,maxB; polygonA->Project(axesB[i],&minA,&maxA); polygonB->Project(axesB[i],&minB,&maxB); float intervalDistance = polygonA->GetIntervalDistance(minA, maxA, minB, maxB); if(intervalDistance >= 0) return false; //Collision not occurring } This function retrieves axes from the polygon: std::vector<vec2> Polygon::GetAxes() { std::vector<vec2> axes; for(int i = 0; i < verts.size(); i++) { vec2 a = verts[i]; vec2 b = verts[(i+1)%verts.size()]; vec2 edge = b-a; axes.push_back(vec2(-edge.y,edge.x).GetNormailzed()); } return axes; } This function returns the normalized vector: vec2 vec2::GetNormailzed() { float mag = sqrt( x*x + y*y ); return *this/mag; } This function projects a polygon onto an axis: void Polygon::Project(vec2* axis, float* min, float* max) { float d = axis->DotProduct(&verts[0]); float _min = d; float _max = d; for(int i = 1; i < verts.size(); i++) { d = axis->DotProduct(&verts[i]); _min = std::min(_min,d); _max = std::max(_max,d); } *min = _min; *max = _max; } This function returns the dot product of the vector with another vector. float vec2::DotProduct(vec2* other) { return (x*other->x + y*other->y); } Could anyone give me a pointer in the right direction to what could be causing this bug?

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  • ArchBeat Link-o-Rama Top 10 for October 21-27, 2012

    - by Bob Rhubart
    The Top 10 most popular items shared on the OTN ArchBeat Facebook Page for the week of October 21-27, 2012. OTN Architect Day: Los Angeles This is your brain on IT architecture. Stuff your cranium with architecture by attending Oracle Technology Network Architect Day in Los Angeles, October 25, 2012, at the Sofitel Los Angeles, 8555 Beverly Boulevard, Los Angeles, CA 90048. Technical sessions, panel Q&A, and peer roundtables—plus a free lunch. [NOTE: The event was last week, of course. Big thanks to the session presenters and especially to those Angelinos who came out for the event.] WebLogic Server 11gR1 Interactive Quick Reference"The WebLogic Server 11gR1 Administration interactive quick reference," explains Juergen Kress, "is a multimedia tool for various terms and concepts used in WebLogic Server architecture. This tool is available for administrators for online or offline use. This is built as a multimedia web page which provides descriptions of WebLogic Server Architectural components, and references to relevant documentation. This tool offers valuable reference information for any complex concept or product in an intuitive and useful manner." Podcast: Are You Future Proof? The latest OTN ArchBeat Podcast series features Oracle ACE Directors Ron Batra, Basheer Khan, and Ronald van Luttikhuizen, three practicing architects in an open discussion about how changes in enterprise IT are raising the bar for success for software architects and developers. Play Oracle Vanquisher Here's a little respite from whatever it is you normally spend your time on. Oracle Vanquisher is an online diversion that makes a game of data center optimization. According to the description: "Armed with a cool Oracle vacuum pack suit and a strategic IT roadmap, you will thwart threats and optimize your data center to increase your company’s stock price and boost your company’s position." Mainly you avoid electric shock and killer birds. The current high score belongs to someone identified as 'TEN." My score? Never mind. Advanced Oracle SOA Suite OOW 2012 PresentationsThe Oracle SOA Product Management team has compiled a complete list of all twelve of their Oracle SOA Suite presentations from Oracle OpenWorld 2012, with links to the slide decks. OAM and OIM 11g Academies Looking for technical how-to content covering Oracle Access Manager and Oracle Identity Manager? The people behind the Oracle Middleware Security blog have indexed relevant blog posts into what they call "Academies." "These indexes contain the articles we’ve written that we believe provide long lasting guidance on OAM and OIM. Posts covered in these series include articles on key aspects of OAM and OIM 11g, best practice architectural guidance, integrations, and customizations." Oracle’s Analytics, Engineered Systems, and Big Data Strategy | Mark Rittman Part 1 of 3 in Oracle ACE Director Mark Rittman's series on Oracle Exalytics, Oracle R Enterprise and Endeca. Oracle ACE Directors Nordic Tour 2012 : Venues and BI Presentations | Mark RittmanOracle ACE Director Mark Rittman shares information on the Oracle ACE Director Tour, as the community leaders make their way through the land of the midnight sun, with events in Copenhagen, Stockholm, Oslo and Helsinki. Following the Thread in OSB | Antony Reynolds Antony Reynolds recently led an Oracle Service Bus POC in which his team needed to get high throughput from an OSB pipeline. "Imagine our surprise when, on stressing the system, we saw it lock up, with large numbers of blocked threads." He shares the details of the problem and the solution in this extensive technical post. OW12: Oracle Business Process Management/Oracle ADF Integration Best Practices | Andrejus Baranovskis The Oracle OpenWorld presentations keep coming! Oracle ACE Director Andrejus Baranovskis shares the slides from "Oracle Business Process Management/Oracle ADF Integration Best Practices," co-presented with Danilo Schmiedel from Opitz Consulting. Thought for the Day "Not everything that can be counted counts, and not everything that counts can be counted." — Albert Einstein (March 14, 1879 – April 18, 1955) Source: Quotes For Software Engineers

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  • How can I keep directories in sync

    - by Guillaume Boudreau
    I have a directory, dirA, that users can work in: they can create, modify, rename and delete files & sub-directores in dirA. I want to keep another directory, dirB, in sync with dirA. What I'd like, is a discussion on finding a working algorithm that would achieve the above, with the limitations listed below. Requirements: 1. Something asynchronous - I don't want to stop file operations in dirA while I work in dirB. 2. I can't assume that I can just blindly rsync dirA to dirB on regular interval - dirA could contain millions of files & directories, and terrabytes of data. Completely walking the dirA tree could take hours. Those two requirements makes this really difficult. Having it asynchronous means that when I start working on a specific file from dirA, it might have moved a lot since it appeared. And the second limitation means that I really need to watch dirA, and work on atomic file operations that I notice. Current (broken) implementation: 1. Log all file & directory operations in dirA. 2. Using a separate process, read that log, and 'repeat' all the logged operations in dirB. Why is it broken: echo 1 > dirA/file1 # Allow the 'log reader' process to create dirB/file1: log = "write dirA/file1"; action = cp dirA/file1 dirB/file1; result = OK echo 1 > dirA/file2 mv dirA/file1 dirA/file3 mv dirA/file2 dirA/file1 rm dirA/file3 # End result: file1 contains '1' # 'log reader' process starts working on the 4 above file operations: log = "write file2"; action = cp dirA/file2 dirB/file2; result = failed: there is no dirA/file2 log = "rename file1 file3"; action = mv dirB/file1 dirB/file3; result = OK log = "rename file2 file1"; action = mv dirB/file2 dirB/file1; result = failed: there is no dirB/file2 log = "delete file3"; action = rm dirB/file3; result = OK # End result in dirB: no more files! Another broken example: echo 1 > dirA/dir1/file1 mv dirA/dir1 dirA/dir2 # 'log reader' process starts working on the 2 above file operations: log = "write file1"; action = cp dirA/dir1/file1 dirB/dir1/file1; result = failed: there is no dirA/dir1/file1 log = "rename dir1 dir2"; action = mv dirB/dir1 dirB/dir2; result = failed: there is no dirA/dir1 # End result if dirB: nothing!

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  • Class instance clustering in object reference graph for multi-entries serialization

    - by Juh_
    My question is on the best way to cluster a graph of class instances (i.e. objects, the graph nodes) linked by object references (the -directed- edges of the graph) around specifically marked objects. To explain better my question, let me explain my motivation: I currently use a moderately complex system to serialize the data used in my projects: "marked" objects have a specific attributes which stores a "saving entry": the path to an associated file on disc (but it could be done for any storage type providing the suitable interface) Those object can then be serialized automatically (eg: obj.save()) The serialization of a marked object 'a' contains implicitly all objects 'b' for which 'a' has a reference to, directly s.t: a.b = b, or indirectly s.t.: a.c.b = b for some object 'c' This is very simple and basically define specific storage entries to specific objects. I have then "container" type objects that: can be serialized similarly (in fact their are or can-be "marked") they don't serialize in their storage entries the "marked" objects (with direct reference): if a and a.b are both marked, a.save() calls b.save() and stores a.b = storage_entry(b) So, if I serialize 'a', it will serialize automatically all objects that can be reached from 'a' through the object reference graph, possibly in multiples entries. That is what I want, and is usually provides the functionalities I need. However, it is very ad-hoc and there are some structural limitations to this approach: the multi-entry saving can only works through direct connections in "container" objects, and there are situations with undefined behavior such as if two "marked" objects 'a'and 'b' both have a reference to an unmarked object 'c'. In this case my system will stores 'c' in both 'a' and 'b' making an implicit copy which not only double the storage size, but also change the object reference graph after re-loading. I am thinking of generalizing the process. Apart for the practical questions on implementation (I am coding in python, and use Pickle to serialize my objects), there is a general question on the way to attach (cluster) unmarked objects to marked ones. So, my questions are: What are the important issues that should be considered? Basically why not just use any graph parsing algorithm with the "attach to last marked node" behavior. Is there any work done on this problem, practical or theoretical, that I should be aware of? Note: I added the tag graph-database because I think the answer might come from that fields, even if the question is not.

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  • MS in Computer Science after BE in electronics

    - by Abhinav
    I am doing my 3rd year Bachelors in Electronics and Electrical Communication but from the first year I have been interested in Computer Science. But at that time it was just my hobby. But in second year when I joined robotics my love for computer science rose. I with my team came in top three in 2 National Competition (Technical fests of different IITs) where we used Image Processing, Hardware interfacing etc. But then I realised that Computer Science is not just about coding. I took many lectures from online free schools like Udacity, Coursera in subjects related to Artificial Intelligence, Building a Search Engine, Design and Analysis of Algorithm, Programming a Robotic Car, Programming Languages, Machine Learning, Software Engineering as a Service, WebApps Engineering, Compilers, Applied Crypotography etc. I also did some courses in Core and Advanced Java in my second year from training institute. I will also be taking course in Statistics, Databases, Discrete Mathematics from 25th June. Now I realized how vast is the field of Computer Science and how efficient you become on deciding algorithms and classifying problems into different subfields which have been thoroughly researched so you don't always do brute force thing or naive programming. Now this field has become kind of passion for me. Adding to the fact I am also doing my 6 months internship in software field in Texas Instruments where I am working on Automation and Algorithms. I also have some 5-6 good college level projects in Softwares and Robotics. I also like Electronics but only some fields like Operating System(this subject was there in Electronics also), Micro Processor, Digital, Computer Architecture, DSPs etc. I really want to pursue MS in some field of Computer Science. I am giving GRE in October/November. Till now I have good CG of around 9.4/10 and my 1 year in college is still left. Do I have any chance that some good University in US will consider me for MS in field related to computer science or Robotics. Also Can you suggest somethings that I can do during this 1 year to increase my chances for MS or should I apply for EECS(Electrical Engineering and Computer Science) and then I can shift more towards Computer Science as my major option. My main aim is to do Phd after Ms in CS if I am able to do that somehow. I know that I have to put much extra effort to understand things in MS than CS undergraduates but I will do that with my full dedication, also when I communicate with my college CS students or during my internship period I didn't feel that I am missing very much stuff that they know and was very comfortable during my internship with software employees.

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  • iwlwifi on lenovo z570 disabled by hardware switch

    - by Kevin Gallagher
    It was working fine with windows 7. The hardware switch is not disabled. I've toggled it back and forth dozens of times. The wifi light never turns on and it always lists as hardware disabled. I have the latest updates installed. I've been searching for solutions, but none of them seem to work for me. I've tried removing acer-wmi. I've tried setting 11n_disable=1. I've tried resetting the bios. I've tried using rfkill to unblock (only removes soft block). I've rebooted dozens of times. The wifi light turns off as soon as grub loads. Edit: I have a usb edimax wireless nic. It shows hardware disabled as well (although rfkill lists as unblocked). If I unload iwlwifi the usb nic works fine. uname -a `Linux xxx-Ideapad-Z570 3.2.0-55-generic #85-Ubuntu SMP Wed Oct 2 12:29:27 UTC 2013 x86_64 x86_64 x86_64 GNU/Linu`x rfkill list 19: phy18: Wireless LAN Soft blocked: no Hard blocked: yes dmesg [43463.022996] Intel(R) Wireless WiFi Link AGN driver for Linux, in-tree: [43463.023002] Copyright(c) 2003-2011 Intel Corporation [43463.023107] iwlwifi 0000:03:00.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17 [43463.023190] iwlwifi 0000:03:00.0: setting latency timer to 64 [43463.023253] iwlwifi 0000:03:00.0: pci_resource_len = 0x00002000 [43463.023257] iwlwifi 0000:03:00.0: pci_resource_base = ffffc900057c8000 [43463.023261] iwlwifi 0000:03:00.0: HW Revision ID = 0x0 [43463.023797] iwlwifi 0000:03:00.0: irq 43 for MSI/MSI-X [43463.024013] iwlwifi 0000:03:00.0: Detected Intel(R) Centrino(R) Wireless-N 1000 BGN, REV=0x6C [43463.024250] iwlwifi 0000:03:00.0: L1 Enabled; Disabling L0S [43463.045496] iwlwifi 0000:03:00.0: device EEPROM VER=0x15d, CALIB=0x6 [43463.045501] iwlwifi 0000:03:00.0: Device SKU: 0X50 [43463.045504] iwlwifi 0000:03:00.0: Valid Tx ant: 0X1, Valid Rx ant: 0X3 [43463.045542] iwlwifi 0000:03:00.0: Tunable channels: 13 802.11bg, 0 802.11a channels [43463.045744] iwlwifi 0000:03:00.0: RF_KILL bit toggled to disable radio. [43463.047652] iwlwifi 0000:03:00.0: loaded firmware version 39.31.5.1 build 35138 [43463.047823] Registered led device: phy18-led [43463.047895] cfg80211: Ignoring regulatory request Set by core since the driver uses its own custom regulatory domain [43463.048037] ieee80211 phy18: Selected rate control algorithm 'iwl-agn-rs' [43463.055533] ADDRCONF(NETDEV_UP): wlan0: link is not ready nm-tool State: connected (global) - Device: wlan0 ---------------------------------------------------------------- Type: 802.11 WiFi Driver: iwlwifi State: unavailable Default: no HW Address: 74:E5:0B:4A:9F:C2 Capabilities: Wireless Properties WEP Encryption: yes WPA Encryption: yes WPA2 Encryption: yes Wireless Access Points lshw -C network *-network DISABLED description: Wireless interface product: Centrino Wireless-N 1000 [Condor Peak] vendor: Intel Corporation physical id: 0 bus info: pci@0000:03:00.0 logical name: wlan0 version: 00 serial: 74:e5:0b:4a:9f:c2 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless configuration: broadcast=yes driver=iwlwifi driverversion=3.2.0-55-generic firmware=39.31.5.1 build 35138 latency=0 link=no multicast=yes wireless=IEEE 802.11bg resources: irq:43 memory:f1500000-f1501fff lspci 03:00.0 Network controller: Intel Corporation Centrino Wireless-N 1000 [Condor Peak]

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  • Taking HRMS to the Cloud to Simplify Human Resources Management

    - by HCM-Oracle
    By Anke Mogannam With human capital management (HCM) a top-of-mind issue for executives in every industry, human resources (HR) organizations are poised to have their day in the sun—proving not just their administrative worth but their strategic value as well.  To make good on that promise, however, HR must modernize. Indeed, if HR is to act as an agent of change—providing the swift reallocation of employees  and the rapid absorption of employee data required for enterprises to shift course on a dime—it must first deal with the disruptive change at its own front door. And increasingly, that means choosing the right technology and human resources management system (HRMS) for managing the entire employee lifecycle. Unfortunately, for most organizations, this task has proved easier said than done. This is because while much has been written about advances in HRMS technology, until recently, most of those advances took the form of disparate on-premises solutions designed to serve very specific purposes. Although this may have resulted in key competencies in certain areas, it also meant that processes for core HR functions like payroll and benefits were being carried out in separate systems from those used for talent management, workforce optimization, training, and so on. With no integration—and no single system of record—processes were disconnected, ease of use was impeded, user experience was diminished, and vital data was left untapped.  Today, however, that scenario has begun to change, and end-to-end cloud-based HCM solutions have moved from wished-for innovations to real-life solutions. Why, then, have HR organizations been so slow in adopting them? The answer—it would seem—is, “It’s complicated.” So complicated, in fact, that 45 percent of the respondents to PwC’s “Annual HR Technology Survey” (for 2013) reported having no formal HR software roadmap, and 40 percent stated that they “did not know” whether their organizations would be increasing their use of cloud or software as a service (SaaS) for HR.  Clearly, HR organizations need help sorting through the morass of HR software options confronting them. But just as clearly, there’s an enormous opportunity awaiting those that do. The trick will come in charting a course that allows HR to leverage existing technology while investing in the cloud-based solutions that will deliver the end-to-end processes, easy-to-understand analytics, and superior adaptability required to simplify—and add value to—every aspect of employee management. The Opportunity therefore is to cut costs, drive Innovation, and increase engagement by moving to cloud-based HCM.  Then you will benefit from one Interface, leverage many access points, and  gain at-a-glance insight across your entire workforce. With many legacy on-premises HR systems not being efficient anymore and cloud-based, integrated systems that span the range of HR functions finally reaching maturity, the time is ripe for moving core HR to the cloud. Indeed, for the first time ever there are more HRMS replacement initiatives than HRMS upgrade initiatives under way, and the majority of them involve moving to the cloud per Cedar Crestone’s 2013-2014 HRMS survey. To learn how you can launch your own cloud HCM initiative and begin using HR to power the enterprise, visit Oracle HRMS in the Cloud and Oracle’s new customer 2 cloud program. Anke Mogannam brings more than 16 years of marketing and human capital management experience in the technology industries to her role at Oracle where she is part of the Human Capital Management applications marketing team. In that role, Anke drives content marketing, messaging, go-to-market activities, integrated marketing campaigns, and field enablement. Prior to joining Oracle, Anke held several roles in communications, marketing, HCM product strategy and product management at PeopleSoft, SAP, Workday and Saba. Follow her on Twitter @amogannam

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  • Creating a frozen bubble clone

    - by Vaughan Hilts
    This photo illustrates the environment: http://i.imgur.com/V4wbp.png I'll shoot the cannon, it'll bounce off the wall and it's SUPPOSED to stick to the bubble. It does at pretty much every other angle. The problem is always reproduced here, when hit off the wall into those bubbles. It also exists in other cases, but I'm not sure what triggers it. What actually happens: The ball will sometimes set to the wrong cell, and my "dropping" code will detect it as a loner and drop it off the stage. *There are many implementations of "Frozen Bubble" on the web, but I can't for the life of me find a good explanation as to how the algorithm for the "Bubble Sticking" works. * I see this: http://www.wikiflashed.com/wiki/BubbleBobble https://frozenbubblexna.svn.codeplex.com/svn/FrozenBubble/ But I can't figure out the algorithims... could anyone explain possibly the general idea behind getting the balls to stick? Code in question: //Counstruct our bounding rectangle for use var nX = currentBall.x + ballvX * gameTime; var nY = currentBall.y - ballvY * gameTime; var movingRect = new BoundingRectangle(nX, nY, 32, 32); var able = false; //Iterate over the cells and draw our bubbles for (var x = 0; x < 8; x++) { for (var y = 0; y < 12; y++) { //Get the bubble at this layout var bubble = bubbleLayout[x][y]; var rowHeight = 27; //If this slot isn't empty, draw if (bubble != null) { var bx = 0, by = 0; if (y % 2 == 0) { bx = x * 32 + 270; by = y * 32 + 45; } else { bx = x * 32 + 270 + 16; by = y * 32 + 45; } //Check var targetBox = new BoundingRectangle(bx, by, 32, 32); if (targetBox.intersects(movingRect)) { able = true; } } } } cellY = Math.round((currentBall.y - 45) / 32); if (cellY % 2 == 0) cellX = Math.round((currentBall.x - 270) / 32); else cellX = Math.round((currentBall.x - 270 - 16) / 32); Any ideas are very much welcome. Things I've tried: Flooring and Ceiling values Changing the wall bounce to a lower value Slowing down the ball None of these seem to affect it. Is there something in my math I'm not getting?

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  • What algorithms can I use to detect if articles or posts are duplicates?

    - by michael
    I'm trying to detect if an article or forum post is a duplicate entry within the database. I've given this some thought, coming to the conclusion that someone who duplicate content will do so using one of the three (in descending difficult to detect): simple copy paste the whole text copy and paste parts of text merging it with their own copy an article from an external site and masquerade as their own Prepping Text For Analysis Basically any anomalies; the goal is to make the text as "pure" as possible. For more accurate results, the text is "standardized" by: Stripping duplicate white spaces and trimming leading and trailing. Newlines are standardized to \n. HTML tags are removed. Using a RegEx called Daring Fireball URLs are stripped. I use BB code in my application so that goes to. (ä)ccented and foreign (besides Enlgish) are converted to their non foreign form. I store information about each article in (1) statistics table and in (2) keywords table. (1) Statistics Table The following statistics are stored about the textual content (much like this post) text length letter count word count sentence count average words per sentence automated readability index gunning fog score For European languages Coleman-Liau and Automated Readability Index should be used as they do not use syllable counting, so should produce a reasonably accurate score. (2) Keywords Table The keywords are generated by excluding a huge list of stop words (common words), e.g., 'the', 'a', 'of', 'to', etc, etc. Sample Data text_length, 3963 letter_count, 3052 word_count, 684 sentence_count, 33 word_per_sentence, 21 gunning_fog, 11.5 auto_read_index, 9.9 keyword 1, killed keyword 2, officers keyword 3, police It should be noted that once an article gets updated all of the above statistics are regenerated and could be completely different values. How could I use the above information to detect if an article that's being published for the first time, is already existing within the database? I'm aware anything I'll design will not be perfect, the biggest risk being (1) Content that is not a duplicate will be flagged as duplicate (2) The system allows the duplicate content through. So the algorithm should generate a risk assessment number from 0 being no duplicate risk 5 being possible duplicate and 10 being duplicate. Anything above 5 then there's a good possibility that the content is duplicate. In this case the content could be flagged and linked to the article's that are possible duplicates and a human could decide whether to delete or allow. As I said before I'm storing keywords for the whole article, however I wonder if I could do the same on paragraph basis; this would also mean further separating my data in the DB but it would also make it easier for detecting (2) in my initial post. I'm thinking weighted average between the statistics, but in what order and what would be the consequences...

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  • Randomly generate directed graph on a grid

    - by Talon876
    I am trying to randomly generate a directed graph for the purpose of making a puzzle game similar to the ice sliding puzzles from Pokemon. This is essentially what I want to be able to randomly generate: http://bulbanews.bulbagarden.net/wiki/Crunching_the_numbers:_Graph_theory. I need to be able to limit the size of the graph in an x and y dimension. In the example given in the link, it would be restricted to an 8x4 grid. The problem I am running into is not randomly generating the graph, but randomly generating a graph, which I can properly map out in a 2d space, since I need something (like a rock) on the opposite side of a node, to make it visually make sense when you stop sliding. The problem with this is that sometimes the rock ends up in the path between two other nodes or possibly on another node itself, which causes the entire graph to become broken. After discussing the problem with a few people I know, we came to a couple of conclusions that may lead to a solution. Including the obstacles in the grid as part of the graph when constructing it. Start out with a fully filled grid and just draw a random path and delete out blocks that will make that path work. The problem then becomes figuring out which ones to delete to avoid introducing an additional, shorter path. We were also thinking a dynamic programming algorithm may be beneficial, though none of us are too skilled with creating dynamic programming algorithms from nothing. Any ideas or references about what this problem is officially called (if it's an official graph problem) would be most helpful. Here are some examples of what I have accomplished so far by just randomly placing blocks and generating the navigation graph from the chosen start/finish. The idea (as described in the previous link) is you start at the green S and want to get to the green F. You do this by moving up/down/left/right and you continue moving in the direction chosen until you hit a wall. In these pictures, grey is a wall, white is the floor, and the purple line is the minimum length from start to finish, and the black lines and grey dots represented possible paths. Here are some bad examples of randomly generated graphs: http://i.stack.imgur.com/9uaM6.png Here are some good examples of randomly generated (or hand tweaked) graphs: i.stack.imgur.com/uUGeL.png (can't post another link, sorry) I've also seemed to notice the more challenging ones when actually playing this as a puzzle are ones which have lots of high degree nodes along the minimum path.

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  • Mastering snow and Java development at jDays in Gothenburg

    - by JavaCecilia
    Last weekend, I took the train from Stockholm to Gothenburg to attend and present at the new Java developer conference jDays. It was professionally arranged in the Swedish exhibition hall close to the amusement park Liseberg and we got a great deal out of the top-level presenters and hallway discussions. Understanding and Improving Your Java Process Our main purpose was to spread information on JVM and our monitoring tools for Java processes, so I held a crash course in the most important terms and concepts if you want to affect the performance of your Java process. From the beginning - the JVM specification to interpretation of heap usage graphs. For correct analysis, you also need to understand something about process memory - you need space for the Java heap (-Xms for initial size and -Xmx for max heap size), but the process memory also contain the thread stacks (to a size of -Xss), JVM internal data structures used for keeping track of Java objects on the heap, method compilation/optimization, native libraries, etc. If you get long pause times, make sure to monitor your application, see the allocation rate and frequency of pause times.My colleague Klara Ward then held a presentation on the Java Mission Control product, the profiling and diagnostics tools suite for HotSpot, coming soon. The room was packed and very appreciated, Klara demonstrated four different scenarios, e.g. how to diagnose and fix latencies due to lock contention for logging.My German colleague, OpenJDK ambassador Dalibor Topic travelled to Sweden to do the second keynote on "Make the Future Java". He let us in on the coming features and roadmaps of Java, now delivering major versions on a two-year schedule (Java 7 2011, Java 8 2013, etc). Also letting us in on where to download early versions of 8, to report problems early on. Software Development in teams Being a scout leader, I'm drilled in different team building and workshop techniques, creating strong groups - of course, I had to attend Henrik Berglund's session on building successful teams. He spoke about the importance of clear goals, autonomy and agreed processes. Thomas Sundberg ended the conference by doing live remote pair programming with Alex in Rumania and a concrete tips for people wanting to try it out (for local collaboration, remember to wash and change clothes). Memory Master Keynote The conference keynote was delivered by the Swedish memory master Mattias Ribbing, showing off by remembering the order of a deck of cards he'd seen once. He made it interactive by forcing the audience to learn a memory mastering technique of remembering ten ordered things by heart, asking us to shout out the order backwards and we made it! I desperately need this - bought the book, will get back on the subject. Continuous Delivery The most impressive presenter was Axel Fontaine on Continuous Delivery. Very well prepared slides with key images of his message and moved about the stage like a rock star. The topic is of course highly interesting, how to create an infrastructure enabling immediate feedback to developers and ability to release your product several times per day. Tomek Kaczanowski delivered a funny and useful presentation on good and bad tests, providing comic relief with poorly written tests and the useful rules of thumb how to rewrite them. To conclude, we had a great time and hope to see you at jDays next year :)

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  • The Future of Air Travel: Intelligence and Automation

    - by BobEvans
    Remember those white-knuckle flights through stormy weather where unexpected plunges in altitude result in near-permanent relocations of major internal organs? Perhaps there’s a better way, according to a recent Wall Street Journal article: “Pilots of a Honeywell International Inc. test plane stayed on their initial flight path, relying on the company's latest onboard radar technology to steer through the worst of the weather. The specially outfitted Boeing 757 barely shuddered as it gingerly skirted some of the most ferocious storm cells over Fort Walton Beach and then climbed above the rest in zero visibility.” Or how about the multifaceted check-in process, which might not wreak havoc on liver location but nevertheless makes you wonder if you’ve been trapped in some sort of covert psychological-stress test? Another WSJ article, called “The Self-Service Airport,” says there’s reason for hope there as well: “Airlines are laying the groundwork for the next big step in the airport experience: a trip from the curb to the plane without interacting with a single airline employee. At the airport of the near future, ‘your first interaction could be with a flight attendant,’ said Ben Minicucci, chief operating officer of Alaska Airlines, a unit of Alaska Air Group Inc.” And in the topsy-turvy world of air travel, it’s not just the passengers who’ve been experiencing bumpy rides: the airlines themselves are grappling with a range of challenges—some beyond their control, some not—that make profitability increasingly elusive in spite of heavy demand for their services. A recent piece in The Economist illustrates one of the mega-challenges confronting the airline industry via a striking set of contrasting and very large numbers: while the airlines pay $7 billion per year to third-party computerized reservation services, the airlines themselves earn a collective profit of only $3 billion per year. In that context, the anecdotes above point unmistakably to the future that airlines must pursue if they hope to be able to manage some of the factors outside of their control (e.g., weather) as well as all of those within their control (operating expenses, end-to-end visibility, safety, load optimization, etc.): more intelligence, more automation, more interconnectedness, and more real-time awareness of every facet of their operations. Those moves will benefit both passengers and the air carriers, says the WSJ piece on The Self-Service Airport: “Airlines say the advanced technology will quicken the airport experience for seasoned travelers—shaving a minute or two from the checked-baggage process alone—while freeing airline employees to focus on fliers with questions. ‘It's more about throughput with the resources you have than getting rid of humans,’ said Andrew O'Connor, director of airport solutions at Geneva-based airline IT provider SITA.” Oracle’s attempting to help airlines gain control over these challenges by blending together a range of its technologies into a solution called the Oracle Airline Data Model, which suggests the following steps: • To retain and grow their customer base, airlines need to focus on the customer experience. • To personalize and differentiate the customer experience, airlines need to effectively manage their passenger data. • The Oracle Airline Data Model can help airlines jump-start their customer-experience initiatives by consolidating passenger data into a customer data hub that drives realtime business intelligence and strategic customer insight. • Oracle’s Airline Data Model brings together multiple types of data that can jumpstart your data-warehousing project with rich out-of-the-box functionality. • Oracle’s Intelligent Warehouse for Airlines brings together the powerful capabilities of Oracle Exadata and the Oracle Airline Data Model to give you real-time strategic insights into passenger demand, revenues, sales channels and your flight network. The airline industry aside, the bullet points above offer a broad strategic outline for just about any industry because the customer experience is becoming pre-eminent in each and there is simply no way to deliver world-class customer experiences unless a company can capture, manage, and analyze all of the relevant data in real-time. I’ll leave you with two thoughts from the WSJ article about the new in-flight radar system from Honeywell: first, studies show that a single episode of serious turbulence can wrack up $150,000 in additional costs for an airline—so, it certainly behooves the carriers to gain the intelligence to avoid turbulence as much as possible. And second, it’s back to that top-priority customer-experience thing and the value that ever-increasing levels of intelligence can deliver. As the article says: “In the cabin, reporters watched screens showing the most intense parts of the nearly 10-mile wide storm, which churned some 7,000 feet below, in vibrant red and other colors. The screens also were filled with tiny symbols depicting likely locations of lightning and hail, which can damage planes and wreak havoc on the nerves of white-knuckle flyers.”  (Bob Evans is senior vice-president, communications, for Oracle.)  

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  • Isometric layer moving inside map

    - by gronzzz
    i'm created isometric map and now trying to limit layer moving. Main idea, that i have left bottom, right bottom, left top, right top points, that camera can not move outside, so player will not see map out of bounds. But i can not understand algorithm of how to do that. It's my layer scale/moving code. - (void)touchBegan:(UITouch *)touch withEvent:(UIEvent *)event { _isTouchBegin = YES; } - (void)touchMoved:(UITouch *)touch withEvent:(UIEvent *)event { NSArray *allTouches = [[event allTouches] allObjects]; UITouch *touchOne = [allTouches objectAtIndex:0]; CGPoint touchLocationOne = [touchOne locationInView: [touchOne view]]; CGPoint previousLocationOne = [touchOne previousLocationInView: [touchOne view]]; // Scaling if ([allTouches count] == 2) { _isDragging = NO; UITouch *touchTwo = [allTouches objectAtIndex:1]; CGPoint touchLocationTwo = [touchTwo locationInView: [touchTwo view]]; CGPoint previousLocationTwo = [touchTwo previousLocationInView: [touchTwo view]]; CGFloat currentDistance = sqrt( pow(touchLocationOne.x - touchLocationTwo.x, 2.0f) + pow(touchLocationOne.y - touchLocationTwo.y, 2.0f)); CGFloat previousDistance = sqrt( pow(previousLocationOne.x - previousLocationTwo.x, 2.0f) + pow(previousLocationOne.y - previousLocationTwo.y, 2.0f)); CGFloat distanceDelta = currentDistance - previousDistance; CGPoint pinchCenter = ccpMidpoint(touchLocationOne, touchLocationTwo); pinchCenter = [self convertToNodeSpace:pinchCenter]; CGFloat predictionScale = self.scale + (distanceDelta * PINCH_ZOOM_MULTIPLIER); if([self predictionScaleInBounds:predictionScale]) { [self scale:predictionScale scaleCenter:pinchCenter]; } } else { // Dragging _isDragging = YES; CGPoint previous = [[CCDirector sharedDirector] convertToGL:previousLocationOne]; CGPoint current = [[CCDirector sharedDirector] convertToGL:touchLocationOne]; CGPoint delta = ccpSub(current, previous); self.position = ccpAdd(self.position, delta); } } - (void)touchEnded:(UITouch *)touch withEvent:(UIEvent *)event { _isDragging = NO; _isTouchBegin = NO; // Check if i need to bounce _touchLoc = [touch locationInNode:self]; } #pragma mark - Update - (void)update:(CCTime)delta { CGPoint position = self.position; float scale = self.scale; static float friction = 0.92f; //0.96f; if(_isDragging && !_isScaleBounce) { _velocity = ccp((position.x - _lastPos.x)/2, (position.y - _lastPos.y)/2); _lastPos = position; } else { _velocity = ccp(_velocity.x * friction, _velocity.y *friction); position = ccpAdd(position, _velocity); self.position = position; } if (_isScaleBounce && !_isTouchBegin) { float min = fabsf(self.scale - MIN_SCALE); float max = fabsf(self.scale - MAX_SCALE); int dif = max > min ? 1 : -1; if ((scale > MAX_SCALE - SCALE_BOUNCE_AREA) || (scale < MIN_SCALE + SCALE_BOUNCE_AREA)) { CGFloat newSscale = scale + dif * (delta * friction); [self scale:newSscale scaleCenter:_touchLoc]; } else { _isScaleBounce = NO; } } }

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  • Finding furthermost point in game world

    - by user13414
    I am attempting to find the furthermost point in my game world given the player's current location and a normalized direction vector in screen space. My current algorithm is: convert player world location to screen space multiply the direction vector by a large number (2000) and add it to the player's screen location to get the distant screen location convert the distant screen location to world space create a line running from the player's world location to the distant world location loop over the bounding "walls" (of which there are always 4) of my game world check whether the wall and the line intersect if so, where they intersect is the furthermost point of my game world in the direction of the vector Here it is, more or less, in code: public Vector2 GetFurthermostWorldPoint(Vector2 directionVector) { var screenLocation = entity.WorldPointToScreen(entity.Location); var distantScreenLocation = screenLocation + (directionVector * 2000); var distantWorldLocation = entity.ScreenPointToWorld(distantScreenLocation); var line = new Line(entity.Center, distantWorldLocation); float intersectionDistance; Vector2 intersectionPoint; foreach (var boundingWall in entity.Level.BoundingWalls) { if (boundingWall.Intersects(line, out intersectionDistance, out intersectionPoint)) { return intersectionPoint; } } Debug.Assert(false, "No intersection found!"); return Vector2.Zero; } Now this works, for some definition of "works". I've found that the further out my distant screen location is, the less chance it has of working. When digging into the reasons why, I noticed that calls to Viewport.Unproject could result in wildly varying return values for points that are "far away". I wrote this stupid little "test" to try and understand what was going on: [Fact] public void wtf() { var screenPositions = new Vector2[] { new Vector2(400, 240), new Vector2(400, -2000), }; var viewport = new Viewport(0, 0, 800, 480); var projectionMatrix = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4, viewport.Width / viewport.Height, 1, 200000); var viewMatrix = Matrix.CreateLookAt(new Vector3(400, 630, 600), new Vector3(400, 345, 0), new Vector3(0, 0, 1)); var worldMatrix = Matrix.Identity; foreach (var screenPosition in screenPositions) { var nearPoint = viewport.Unproject(new Vector3(screenPosition, 0), projectionMatrix, viewMatrix, worldMatrix); var farPoint = viewport.Unproject(new Vector3(screenPosition, 1), projectionMatrix, viewMatrix, worldMatrix); Console.WriteLine("For screen position {0}:", screenPosition); Console.WriteLine(" Projected Near Point = {0}", nearPoint.TruncateZ()); Console.WriteLine(" Projected Far Point = {0}", farPoint.TruncateZ()); Console.WriteLine(); } } The output I get on the console is: For screen position {X:400 Y:240}: Projected Near Point = {X:400 Y:629.571 Z:599.0967} Projected Far Point = {X:392.9302 Y:-83074.98 Z:-175627.9} For screen position {X:400 Y:-2000}: Projected Near Point = {X:400 Y:626.079 Z:600.7554} Projected Far Point = {X:390.2068 Y:-767438.6 Z:148564.2} My question is really twofold: what am I doing wrong with the unprojection such that it varies so wildly and, thus, does not allow me to determine the corresponding world point for my distant screen point? is there a better way altogether to determine the furthermost point in world space given a current world space location, and a directional vector in screen space?

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  • How to handle encryption key conflicts when synchronizing data?

    - by Rafael
    Assume that there is data that gets synchronized between several devices. The data is protected with a symmetric encryption algorithm and a key. The key is stored on each device and encrypted with a password. When a user changes the password only the key gets re-encrypted. Under normal circumstances, when there is a good network connection to other peers, the current key gets synchronized and all data on the new device gets encrypted with the same key. But how to handle situations where a new device doesn’t have a network connection and e.g. creates its own new, but incompatible key? How to keep the usability as high as possible under such circumstances? The application could detect that there is no network and hence refuse to start. That’s very bad usability in my opinion, because the application isn’t functional at all in this case. I don’t consider this a solution. The application could ignore the missing network connection and create a new key. But what to do when the application gains a network connection? There will be several incompatible keys and some parts of the underlying data could only be encrypted with one key and other parts with another key. The situation would get worse if there would be more keys than just two and the application would’ve to ask every time for a password when another object that should get decrypted with another key would be needed. It is very messy and time consuming to try to re-encrypt all data that is encrypted with another key with a main key. What should be the main key at all in this case? The oldest key? The key with the most encrypted objects? What if the key got synchronized but not all objects that got encrypted with this particular key? How should the user know for which particular password the application asks and why it takes probably very long to re-encrypt the data? It’s very hard to describe encryption “issues” to users. So far I didn’t find an acceptable solution, nor some kind of generic strategy. Do you have some hints about a concrete strategy or some books / papers that describe synchronization of symmetrically encrypted data with keys that could cause conflicts?

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  • Top 5 Reasons to Invest in Enterprise 2.0 Technologies

    - by kellsey.ruppel(at)oracle.com
    In 2010, Oracle's portal, content management, and collaboration solutions evolved rapidly, supported by increasingly deep integrations across Oracle Fusion Middleware and the entire Oracle stack. In light of these developments, we asked Vince Casarez, vice president of Enterprise 2.0 product management, for his top five reasons to invest in Enterprise 2.0 (E2.0) technologies--including real-world examples of businesses already realizing the benefits of next-generation E2.0 technologies. 1. Provide a modern user experience As E2.0 technologies gain widespread adoption, customers and employees expect intuitive Web experiences that are both interactive and community-based. By partnering with Oracle, Alcatel-Lucent Enterprise Group is already making that happen. With 76,000 employees and operations in more than 100 countries, the company wanted a streamlined, personalized user experience with more relevant content in fewer clicks. Working with Oracle, they created a global support portal that supports personalization and integration with Oracle Business Intelligence Enterprise Edition and Oracle E-Business Suite--and drives collaboration with tools such as wikis, blogs, and forums. Learn more about Alcatel-Lucent Enterprise Group's Global Support Portal in this Webcast. 2. Improve productivity and collaboration As E2.0 technologies mature, Oracle anticipates companies moving beyond the idea of simply creating yet another Facebook-like destination for its employees, and instead shaping work environments around specific business tasks. After rapid growth--both organic and through acquisition--construction and infrastructure services leader Balfour Beatty found itself with multiple homegrown intranet sites with very minimal content-sharing capabilities. Today, thanks to Oracle WebCenter Suite, Oracle WebCenter Spaces, Oracle WebCenter Services, and Oracle Universal Content Management, Balfour Beatty is benefiting from collaborative workspaces, a central place to use and work with documents, and unified search across content. 3. Leverage business processes and applications Modern portals are now able to integrate users, content, and business processes in unprecedented ways. To take advantage of these new possibilities, leading dairy provider Land O'Lakes has implemented a fully integrated ERP solution together with Oracle's ECM platform. As a result, Land O'Lakes has been able to achieve better information management and compliance, increased adoption rates for enterprise tools, and increased business process efficiency thanks to more effective information sharing and collaboration. 4. Enhance customer and supplier relationships Companies have begun to move beyond the idea that E2.0 simply means enabling customer reviews or embedding chat functionality. They are taking E2.0 to the next level and providing interactive experiences for their customers. For example, to enhance customer and supplier relationships, Wind River, a global leader in device software optimization, successfully partnered with Oracle to: Integrate ERP and ECM content to provide customers the latest and most relevant support information for products they own Enable customers to personalize their support experience and receive updates regarding patches, application notes, and other relevant content Enable discussions, wikis, and blogs for more efficient collaboration 5. Increase business visibility and responsiveness By strategically embedding collaboration and communication tools into specific business contexts, companies significantly increase visibility into changing business conditions--and can respond much more agilely. Texas A&M University System--one of the largest systems of higher education in the U.S.--partnered with Oracle to create a unified repository that would enable the retrieval of research and grant data from disparate systems via an Enterprise 2.0 user interface. By enabling researchers to customize their own portals with easy-to-use tools, they have also been able to significantly reduce their reliance on the IT department. Learn how other Oracle customers are leveraging Enterprise 2.0 technologies.

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  • 2D SAT Collision Detection not working when using certain polygons (With example)

    - by sFuller
    My SAT algorithm falsely reports that collision is occurring when using certain polygons. I believe this happens when using a polygon that does not contain a right angle. Here is a simple diagram of what is going wrong: Here is the problematic code: std::vector<vec2> axesB = polygonB->GetAxes(); //loop over axes B for(int i = 0; i < axesB.size(); i++) { float minA,minB,maxA,maxB; polygonA->Project(axesB[i],&minA,&maxA); polygonB->Project(axesB[i],&minB,&maxB); float intervalDistance = polygonA->GetIntervalDistance(minA, maxA, minB, maxB); if(intervalDistance >= 0) return false; //Collision not occurring } This function retrieves axes from the polygon: std::vector<vec2> Polygon::GetAxes() { std::vector<vec2> axes; for(int i = 0; i < verts.size(); i++) { vec2 a = verts[i]; vec2 b = verts[(i+1)%verts.size()]; vec2 edge = b-a; axes.push_back(vec2(-edge.y,edge.x).GetNormailzed()); } return axes; } This function returns the normalized vector: vec2 vec2::GetNormailzed() { float mag = sqrt( x*x + y*y ); return *this/mag; } This function projects a polygon onto an axis: void Polygon::Project(vec2* axis, float* min, float* max) { float d = axis->DotProduct(&verts[0]); float _min = d; float _max = d; for(int i = 1; i < verts.size(); i++) { d = axis->DotProduct(&verts[i]); _min = std::min(_min,d); _max = std::max(_max,d); } *min = _min; *max = _max; } This function returns the dot product of the vector with another vector. float vec2::DotProduct(vec2* other) { return (x*other->x + y*other->y); } Could anyone give me a pointer in the right direction to what could be causing this bug? Edit: I forgot this function, which gives me the interval distance: float Polygon::GetIntervalDistance(float minA, float maxA, float minB, float maxB) { float intervalDistance; if (minA < minB) { intervalDistance = minB - maxA; } else { intervalDistance = minA - maxB; } return intervalDistance; //A positive value indicates this axis can be separated. } Edit 2: I have recreated the problem in HTML5/Javascript: Demo

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  • Software Tuned to Humanity

    - by Phil Factor
    I learned a great deal from a cynical old programmer who once told me that the ideal length of time for a compiler to do its work was the same time it took to roll a cigarette. For development work, this is oh so true. After intently looking at the editing window for an hour or so, it was a relief to look up, stretch, focus the eyes on something else, and roll the possibly-metaphorical cigarette. This was software tuned to humanity. Likewise, a user’s perception of the “ideal” time that an application will take to move from frame to frame, to retrieve information, or to process their input has remained remarkably static for about thirty years, at around 200 ms. Anything else appears, and always has, to be either fast or slow. This could explain why commercial applications, unlike games, simulations and communications, aren’t noticeably faster now than they were when I started programming in the Seventies. Sure, they do a great deal more, but the SLAs that I negotiated in the 1980s for application performance are very similar to what they are nowadays. To prove to myself that this wasn’t just some rose-tinted misperception on my part, I cranked up a Z80-based Jonos CP/M machine (1985) in the roof-space. Within 20 seconds from cold, it had loaded Wordstar and I was ready to write. OK, I got it wrong: some things were faster 30 years ago. Sure, I’d now have had all sorts of animations, wizzy graphics, and other comforting features, but it seems a pity that we have used all that extra CPU and memory to increase the scope of what we develop, and the graphical prettiness, but not to speed the processes needed to complete a business procedure. Never mind the weight, the response time’s great! To achieve 200 ms response times on a Z80, or similar, performance considerations influenced everything one did as a developer. If it meant writing an entire application in assembly code, applying every smart algorithm, and shortcut imaginable to get the application to perform to spec, then so be it. As a result, I’m a dyed-in-the-wool performance freak and find it difficult to change my habits. Conversely, many developers now seem to feel quite differently. While all will acknowledge that performance is important, it’s no longer the virtue is once was, and other factors such as user-experience now take precedence. Am I wrong? If not, then perhaps we need a new school of development technique to rival Agile, dedicated once again to producing applications that smoke the rear wheels rather than pootle elegantly to the shops; that forgo skeuomorphism, cute animation, or architectural elegance in favor of the smell of hot rubber. I struggle to name an application I use that is truly notable for its blistering performance, and would dearly love one to do my everyday work – just as long as it doesn’t go faster than my brain.

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  • Per-pixel collision detection - why does XNA transform matrix return NaN when adding scaling?

    - by JasperS
    I looked at the TransformCollision sample on MSDN and added the Matrix.CreateTranslation part to a property in my collision detection code but I wanted to add scaling. The code works fine when I leave scaling commented out but when I add it and then do a Matrix.Invert() on the created translation matrix the result is NaN ({NaN,NaN,NaN},{NaN,NaN,NaN},...) Can anyone tell me why this is happening please? Here's the code from the sample: // Build the block's transform Matrix blockTransform = Matrix.CreateTranslation(new Vector3(-blockOrigin, 0.0f)) * // Matrix.CreateScale(block.Scale) * would go here Matrix.CreateRotationZ(blocks[i].Rotation) * Matrix.CreateTranslation(new Vector3(blocks[i].Position, 0.0f)); public static bool IntersectPixels( Matrix transformA, int widthA, int heightA, Color[] dataA, Matrix transformB, int widthB, int heightB, Color[] dataB) { // Calculate a matrix which transforms from A's local space into // world space and then into B's local space Matrix transformAToB = transformA * Matrix.Invert(transformB); // When a point moves in A's local space, it moves in B's local space with a // fixed direction and distance proportional to the movement in A. // This algorithm steps through A one pixel at a time along A's X and Y axes // Calculate the analogous steps in B: Vector2 stepX = Vector2.TransformNormal(Vector2.UnitX, transformAToB); Vector2 stepY = Vector2.TransformNormal(Vector2.UnitY, transformAToB); // Calculate the top left corner of A in B's local space // This variable will be reused to keep track of the start of each row Vector2 yPosInB = Vector2.Transform(Vector2.Zero, transformAToB); // For each row of pixels in A for (int yA = 0; yA < heightA; yA++) { // Start at the beginning of the row Vector2 posInB = yPosInB; // For each pixel in this row for (int xA = 0; xA < widthA; xA++) { // Round to the nearest pixel int xB = (int)Math.Round(posInB.X); int yB = (int)Math.Round(posInB.Y); // If the pixel lies within the bounds of B if (0 <= xB && xB < widthB && 0 <= yB && yB < heightB) { // Get the colors of the overlapping pixels Color colorA = dataA[xA + yA * widthA]; Color colorB = dataB[xB + yB * widthB]; // If both pixels are not completely transparent, if (colorA.A != 0 && colorB.A != 0) { // then an intersection has been found return true; } } // Move to the next pixel in the row posInB += stepX; } // Move to the next row yPosInB += stepY; } // No intersection found return false; }

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  • Dynamic Bind9 + DHCP

    - by AcidRod75
    i have been working on setup a server for my internal network, so far i have a working isc-dhcp-server that can upgrade a chrooted BIND9 (on the same machine), i need to add some static entries on the DNS, so users can resolve the websites that resides in our DMZ. What i had tryed all ready was to modify the /etc/bind/named.conf.local with this info: // // Do any local configuration here // // Consider adding the 1918 zones here, if they are not used in your // organization //include "/etc/bind/zones.rfc1918"; key DHCP_UPDATER { algorithm HMAC-MD5.SIG-ALG.REG.INT; secret "MySuperSecretHash"; (this is not the real value BTW) }; zone "quality.internal" IN { type master; file "/var/lib/bind/quality.internal.db"; allow-update { key DHCP_UPDATER; }; }; zone "0.10.10.in-addr.arpa" { type master; file "/var/lib/bind/rev.10.10.0.in-addr.arpa"; allow-update { key DHCP_UPDATER; }; }; logging { channel query.log { file "/var/log/named/query.log"; severity debug 3; }; category queries { query.log; }; }; --- EOF ---- then i added this 2 entries: zone "ourserver.internal" IN { type master; file "/var/lib/bind/ourserver.internal.db"; }; zone "0.16.172.in-addr.arpa" { type master; file "/var/lib/bind/rev.172.16.0.in-addr.arpa"; }; ---- EOF ---- So.. i created the files ourserver.internal.db and rev.172.16.0.in-addr.arpa placed them BOTH in /var/lib/bind/ and changed the permisions so the bind user can access them, restated the service... when i do a NSLOOKUP www.ourserver.internal i get: Server: 127.0.0.1 Address: 127.0.0.1#53 ** server can't find www.ourserver.internal: NXDOMAIN BUT when i do a reverse lookup.... Server: 127.0.0.1 Address: 127.0.0.1#53 5.0.16.172.in-addr.arpa name = www.ourserver.internal I do not understand what's wrong. Some help with this will save me from installing a new DNS server at the DMZ JUST to host internal site names- TY in advance BTW: the server i'm using has Ubuntu Server 11.10 fully patched.

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  • Generating tileable terrain using Perlin Noise [duplicate]

    - by terrorcell
    This question already has an answer here: How do you generate tileable Perlin noise? 9 answers I'm having trouble figuring out the solution to this particular algorithm. I'm using the Perlin Noise implementation from: https://code.google.com/p/mikeralib/source/browse/trunk/Mikera/src/main/java/mikera/math/PerlinNoise.java Here's what I have so far: for (Chunk chunk : chunks) { PerlinNoise noise = new PerlinNoise(); for (int y = 0; y < CHUNK_SIZE_HEIGHT; ++y) { for (int x = 0; x < CHUNK_SIZE_WIDTH; ++x) { int index = get1DIndex(y, CHUNK_SIZE_WIDTH, x); float val = 0; for (int i = 2; i <= 32; i *= i) { double n = noise.tileableNoise2(i * x / (float)CHUNK_SIZE_WIDTH, i * y / (float)CHUNK_SIZE_HEIGHT, CHUNK_SIZE_WIDTH, CHUNK_SIZE_HEIGHT); val += n / i; } // chunk tile at [index] gets set to the colour 'val' } } } Which produces something like this: Each chunk is made up of CHUNK_SIZE number of tiles, and each tile has a TILE_SIZE_WIDTH/HEIGHT. I think it has something to do with the inner-most for loop and the x/y co-ords given to the noise function, but I could be wrong. Solved: PerlinNoise noise = new PerlinNoise(); for (Chunk chunk : chunks) { for (int y = 0; y < CHUNK_SIZE_HEIGHT; ++y) { for (int x = 0; x < CHUNK_SIZE_WIDTH; ++x) { int index = get1DIndex(y, CHUNK_SIZE_WIDTH, x); float val = 0; float xx = x * TILE_SIZE_WIDTH + chunk.x; float yy = y * TILE_SIZE_HEIGHT + chunk.h; int w = CHUNK_SIZE_WIDTH * TILE_SIZE_WIDTH; int h = CHUNK_SIZE_HEIGHT * TILE_SIZE_HEIGHT; for (int i = 2; i <= 32; i *= i) { double n = noise.tileableNoise2(i * xx / (float)w, i * yy / (float)h, w, h); val += n / i; } // chunk tile at [index] gets set to the colour 'val' } } }

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  • Identifying which pattern fits better.

    - by Daniel Grillo
    I'm developing a software to program a device. I have some commands like Reset, Read_Version, Read_memory, Write_memory, Erase_memory. Reset and Read_Version are fixed. They don't need parameters. Read_memory and Erase_memory need the same parameters that are Length and Address. Write_memory needs Lenght, Address and Data. For each command, I have the same steps in sequence, that are something like this sendCommand, waitForResponse, treatResponse. I'm having difficulty to identify which pattern should I use. Factory, Template Method, Strategy or other pattern. Edit I'll try to explain better taking in count the given comments and answers. I've already done this software and now I'm trying to refactoring it. I'm trying to use patterns, even if it is not necessary because I'm taking advantage of this little software to learn about some patterns. Despite I think that one (or more) pattern fits here and it could improve my code. When I want to read version of the software of my device, I don't have to assembly the command with parameters. It is fixed. So I have to send it. After wait for response. If there is a response, treat (or parse) it and returns. To read a portion of the memory (maximum of 256 bytes), I have to assembly the command using the parameters Len and Address. So I have to send it. After wait for response. If there is a response, treat (or parse) it and returns. To write a portion in the memory (maximum of 256 bytes), I have to assembly the command using the parameters Len, Address and Data. So I have to send it. After wait for response. If there is a response, treat (or parse) it and returns. I think that I could use Template Method because I have almost the same algorithm for all. But the problem is some commands are fixes, others have 2 or 3 parameters. I think that parameters should be passed on the constructor of the class. But each class will have a constructor overriding the abstract class constructor. Is this a problem for the template method? Should I use other pattern?

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  • Learning by doing (and programming by trial and error)

    - by AlexBottoni
    How do you learn a new platform/toolkit while producing working code and keeping your codebase clean? When I know what I can do with the underlying platform and toolkit, I usually do this: I create a new branch (with GIT, in my case) I write a few unit tests (with JUnit, for example) I write my code until it passes my tests So far, so good. The problem is that very often I do not know what I can do with the toolkit because it is brand new to me. I work as a consulant so I cannot have my preferred language/platform/toolkit. I have to cope with whatever the customer uses for the task at hand. Most often, I have to deal (often in a hurry) with a large toolkit that I know very little so I'm forced to "learn by doing" (actually, programming by "trial and error") and this makes me anxious. Please note that, at some point in the learning process, usually I already have: read one or more five-stars books followed one or more web tutorials (writing working code a line at a time) created a couple of small experimental projects with my IDE (IntelliJ IDEA, at the moment. I use Eclipse, Netbeans and others, as well.) Despite all my efforts, at this point usually I can just have a coarse understanding of the platform/toolkit I have to use. I cannot yet grasp each and every detail. This means that each and every new feature that involves some data preparation and some non-trivial algorithm is a pain to implement and requires a lot of trial-and-error. Unfortunately, working by trial-and-error is neither safe nor easy. Actually, this is the phase that makes me most anxious: experimenting with a new toolkit while producing working code and keeping my codebase clean. Usually, at this stage I cannot use the Eclipse Scrapbook because the code I have to write is already too large and complex for this small tool. In the same way, I cannot use any more an indipendent small project for my experiments because I need to try the new code in place. I can just write my code in place and rely on GIT for a safe bail-out. This makes me anxious because this kind of intertwined, half-ripe code can rapidly become incredibly hard to manage. How do you face this phase of the development process? How do you learn-by-doing without making a mess of your codebase? Any tips&tricks, best practice or something like that?

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  • What Counts for a DBA: Skill

    - by drsql
    “Practice makes perfect:” right? Well, not exactly. The reality of it all is that this saying is an untrustworthy aphorism. I discovered this in my “younger” days when I was a passionate tennis player, practicing and playing 20+ hours a week. No matter what my passion level was, without some serious coaching (and perhaps a change in dietary habits), my skill level was never going to rise to a level where I could make any money at the sport that involved something other than selling tennis balls at a sporting goods store. My game may have improved with all that practice but I had too many bad practices to overcome. Practice by itself merely reinforces what we know and what we can figure out naturally. The truth is actually closer to the expression used by Vince Lombardi: “Perfect practice makes perfect.” So how do you get to become skilled as a DBA if practice alone isn’t sufficient? Hit the Internet and start searching for SQL training and you can find 100 different sites. There are also hundreds of blogs, magazines, books, conferences both onsite and virtual. But then how do you know who is good? Unfortunately often the worst guide can be to find out the experience level of the writer. Some of the best DBAs are frighteningly young, and some got their start back when databases were stored on stacks of paper with little holes in it. As a programmer, is it really so hard to understand normalization? Set based theory? Query optimization? Indexing and performance tuning? The biggest barrier often is previous knowledge, particularly programming skills cultivated before you get started with SQL. In the world of technology, it is pretty rare that a fresh programmer will gravitate to database programming. Database programming is very unsexy work, because without a UI all you have are a bunch of text strings that you could never impress anyone with. Newbies spend most of their time building UIs or apps with procedural code in C# or VB scoring obvious interesting wins. Making matters worse is that SQL programming requires mastery of a much different toolset than most any mainstream programming skill. Instead of controlling everything yourself, most of the really difficult work is done by the internals of the engine (written by other non-relational programmers…we just can’t get away from them.) So is there a golden road to achieving a high skill level? Sadly, with tennis, I am pretty sure I’ll never discover it. However, with programming it seems to boil down to practice in applying the appropriate techniques for whatever type of programming you are doing. Can a C# programmer build a great database? As long as they don’t treat SQL like C#, absolutely. Same goes for a DBA writing C# code. None of this stuff is rocket science, as long as you learn to understand that different types of programming require different skill sets and you as a programmer must recognize the difference between one of the procedural languages and SQL and treat them differently. Skill comes from practicing doing things the right way and making “right” a habit.

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