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  • learn the programming language for computing functions about integers

    - by asd
    Hi I know something about Pascal, Mathematica and Matlab, but I dont have any idea about C,C++,C# languages. I want to learn one of the languages that they they are fast and exact to compute some arithmetic functions for large numbers(for example larger than $10^3000$). I asked somebody and he said he used C++ and he said I computed this sequence in less than 10 min. I want to know C, C++, C# and visual kind of theses programs and know which is better for my goal. Let $f$ be an arithmetic function and A={k1,k2,...,kn} are integers in increasing order. Now I want to start with k1 and compare f(ki) with f(k1). If f(ki)f(k1), put ki as k1. Now start with ki, and compare f(kj) with f(ki), for ji. If f(kj)f(ki), put kj as ki, and repeat this procedure. At the end we will have a sub sequence B={L1,...,Lm} of A by this property: f(L(i+1))f(L(i)), for any 1<=i<=m-1 I have written a code for this program with Mathematica, and it take some hours to compute f of ki's or the set B for large numbers. For example, let f is the divisor function of integers. Do you know how to write the code for my purpose in Mathematica or Matlab. Mathematica is preferable.

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  • Managing Kindle Fire with on 12.04 via Micro-USB

    - by pirtle
    To begin, I have read both Is there a way to get a Kindle Fire to work with 12.04? and How can I transfer files to a Kindle Fire with a Micro-USB cable? My problem is that I am unable to mount my Kindle Fire in order to add books to it. I have installed calibre, but it is unable to manage any devices until the computer itself has recognized it. The latter post had an excellent answer (provided by @jeremiah) that was making some progress. Unfortunately, I think I don't know enough about the -t flag used with mount. This is what I've done... Ran dmesg to locate the device: [ 3.920886] sd 6:0:0:0: [sdb] Attached SCSI removable disk Confirmed it's location: $ sudo ls -l /dev/disk/by-id lrwxrwxrwx 1 root root 9 Aug 18 15:52 usb-Amazon_Kindle_3C6C002600000001-0:0 -> ../../sdb So we know that my Kindle is recognized on /dev/sdb. I then used the mount command suggested by @jeremiah: $ sudo mount -t ext3 /dev/sdb/ /mnt/kindle/ mount: no medium found on /dev/sdb The same error occurs for sudo mount /dev/sdb /mnt/kindle. Note: I have created the 'kindle' directory in 'mnt' Any suggestions?

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  • 2D Rectangle Collision Response with Multiple Rectangles

    - by Justin Skiles
    Similar to: Collision rectangle response I have a level made up of tiles where the edges of the level are made up of collidable rectangles. The player's collision box is represented by a rectangle as well. The player can move in 8 directions. The player's velocity is equal in X and Y directions and constant. Each update, I am checking the player's collision against all tiles that are a certain distance away. When the player collides with a rectangle, I am finding the intersection depth and resolving along the most shallow axis followed by the other axis. This resolution happens for both axes simultaneously. See below for two examples of situations where I am having trouble. Moving up-left against the left wall In the scenario below, the player is colliding with two tiles. The tile intersection depth is equal on both axes for the top tile and more shallow in the X axis for the middle tile. Because the player is moving up the wall, the player should slide in an upward direction along the wall. This works properly as long as the rectangle with the more shallow depth is evaluated first. If the equal intersection depth rectangle is evaluated first, there is a chance the player becomes stuck. Moving up-left against the top wall Here is an identical scenario with the exception that the collision is with the top wall. The same problem occurs at the corners when intersection depth is equal for both axes. I guess my overall question is: How can I ensure that collision response occurs on tiles that have non-equal intersection depth before tiles that have equal intersection depth in order to get around the weirdness that occurs at these corners. Sean's answer in the linked question was good, but his solution required having different velocity components in a certain direction. My situation has equal velocities, so there's no good way to tell which direction to resolve at corners. I hope I have made my explanation clear.

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  • How to make Unity 3D work with Bumblebee using the Intel chipset

    - by EboMike
    I have a Sony VAIO S laptop with the dreaded Optimus and finally managed to get Bumblebee to work fully on Ubuntu 12.04 so that I can utilize both the hardware acceleration of the Intel chipset as well as the Nvidia one via optirun and/or bumble-app-settings. However, the desktop effects don't work. But they should, I vaguely remember that they worked for a while before I had Bumblebee installed. This is what I get with the support test: :~$ /usr/lib/nux/unity_support_test -p Xlib: extension "NV-GLX" missing on display ":0". OpenGL vendor string: Tungsten Graphics, Inc OpenGL renderer string: Mesa DRI Intel(R) Ivybridge Mobile OpenGL version string: 1.4 (2.1 Mesa 8.0.2) Not software rendered: yes Not blacklisted: yes GLX fbconfig: yes GLX texture from pixmap: yes GL npot or rect textures: yes GL vertex program: yes GL fragment program: yes GL vertex buffer object: no GL framebuffer object: yes GL version is 1.4+: yes Unity 3D supported: no First of all, I kind of doubt that the chipset doesn't support VBOs (essentially a standard feature in GL). Neither Xorg.0.log nor Xorg.8.log show any particular errors. As for the Nvidia drivers: In order to get them to work, I had to install the 304.22 drivers (older ones wouldn't work). They clobbered libglx.so, so I reinstated the xserver-xorg-core libglx.so in its original place, moved Nvidia's libglx.so to an nvidia-specific folder and specified that folder in the bumblebee.config. That seems to work and shouldn't cause the problem I see here. For fun, I tried to use the Nvidia chipset for Unity, but that didn't fly either: ~$ optirun /usr/lib/nux/unity_support_test -p OpenGL vendor string: NVIDIA Corporation OpenGL renderer string: GeForce GT 640M LE/PCIe/SSE2 OpenGL version string: 4.2.0 NVIDIA 304.22 Not software rendered: yes Not blacklisted: yes GLX fbconfig: yes GLX texture from pixmap: no GL npot or rect textures: yes GL vertex program: yes GL fragment program: yes GL vertex buffer object: yes GL framebuffer object: yes GL version is 1.4+: yes Unity 3D supported: no

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  • Is it OK to use dynamic typing to reduce the amount of variables in scope?

    - by missingno
    Often, when I am initializing something I have to use a temporary variable, for example: file_str = "path/to/file" file_file = open(file) or regexp_parts = ['foo', 'bar'] regexp = new RegExp( regexp_parts.join('|') ) However, I like to reduce the scope my variables to the smallest scope possible so there is less places where they can be (mis-)used. For example, I try to use for(var i ...) in C++ so the loop variable is confined to the loop body. In these initialization cases, if I am using a dynamic language, I am then often tempted to reuse the same variable in order to prevent the initial (and now useless) value from being used latter in the function. file = "path/to/file" file = open(file) regexp = ['...', '...'] regexp = new RegExp( regexp.join('|') ) The idea is that by reducing the number of variables in scope I reduce the chances to misuse them. However this sometimes makes the variable names look a little weird, as in the first example, where "file" refers to a "filename". I think perhaps this would be a non issue if I could use non-nested scopes begin scope1 filename = ... begin scope2 file = open(filename) end scope1 //use file here //can't use filename on accident end scope2 but I can't think of any programming language that supports this. What rules of thumb should I use in this situation? When is it best to reuse the variable? When is it best to create an extra variable? What other ways do we solve this scope problem?

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  • A list of 'best practices' for extending the life between charges of a notebook battery.

    - by Tim Visher
    Hello Everyone, I'd like to compile a list of best practices for getting the most out of a single charge of a typical notebook battery (be it Li-Ion or Li-Poly). Sources would be great as well. I've heard, for instance, that the best things to do to improve battery performance (not the total lifetime of the battery, just single charge performance) are, in descending order of effectiveness: Turn your display all the way down. Turn off WiFi Turn off Bluetooth Spin down disks when they're not in use. etc… I'd like to get sources together for these and other tips for extending life-between-charge for any battery on any notebook (as these really are all about Demand Management rather than Life lime extension. Thanks!

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  • Mobile App Notifications in the Enterprise Space: UX Considerations

    - by ultan o'broin
    Here is a really super website of UX patterns for Android: Android Patterns. I was particularly interested in the event-driven notification patterns (aka status bar notifications to developers). Android - unlike iOS (i.e., the iPhone) - offers a superior centralized notifications system for users.   (Figure copyright Android Patterns)   Research in the enterprise applications space shows how users on-the-go, prefer this approach, as: Users can manage their notification alerts centrally, across all media, apps and for device activity, and decide the order in which to deal with them, and when. Notifications, unlike messages in a dialog or information message in the UI, do not block a task flow (and we need to keep task completion to under three minutes). See the Anti-Patterns slideshare presentation on this blocking point too. These notifications must never interrupt a task flow by launching an activity from the background. Instead, the user can launch an activity from the notification. What users do need is the ability to filter this centralized approach, and to personalize the experience of which notifications are added, what the reminder is, ability to turn off, and so on. A related point concerning notifications is when used to provide users with a record of actions then you can lighten up on lengthy confirmation messages that pop up (toasts in the Android world) used when transactions or actions are sent for processing or into a workflow. Pretty much all the confirmation needs to say is the action is successful along with key data such as dollar amount, customer name, or whatever. I am a user of Android (Nexus S), BlackBerry (Curve), and iOS devices (iPhone 3GS and 4). In my opinion, the best notifications user experience for the enterprise user is offered by Android. Blackberry is good, but not as polished and way clunkier than Android’s. What you get on the iPhone, out of the box, is useless in the enterprise. Technorati Tags: Android,iPhone,Blackerry,messages,usablility,user assistance,userexperience,Oracle,patterns,notifications,alerts

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  • How to send connection type (SSH|Telnet) info in Radius Access Requests on Cisco router?

    - by Gianni Costanzi
    I've configured the following on a cisco router: aaa authentication login default group radius local ! radius-server host x.x.x.x auth-port 1012 acct-port 1013 radius-server host y.y.y.y auth-port 1012 acct-port 1013 radius-server retransmit 1 radius-server timeout 3 radius-server key 7 xxxxxxxxx I'd like to be able to specify some radius options in order to add information about the type of connection for which a user is being authenticated, i.e. I'd like the radius server to receive in the Cisco Router's Radius Access Request information about the connection being SSH or Telnet.. I'd like to find something that automatically adds this info in the access request, without specific configurations on VTY lines dedicated to SSH and to Telnet. Any idea about that?

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  • Desktop Fun: Snow Covered Trees Wallpaper Collection

    - by Asian Angel
    Trees can become beautiful works of natural art when snow accumulates on them and make you feel as if you have stepped into another world when walking through them. So grab your jacket, gloves, and snowboots for a journey through this frosty scenery with our Snow Covered Trees Wallpaper Collection. Note: Click on the picture to see the full-size image—these wallpapers vary in size so you may need to crop, stretch, or place them on a colored background in order to best match them to your screen’s resolution. For more wallpapers be certain to see our great collections in the Desktop Fun section. Latest Features How-To Geek ETC HTG Projects: How to Create Your Own Custom Papercraft Toy How to Combine Rescue Disks to Create the Ultimate Windows Repair Disk What is Camera Raw, and Why Would a Professional Prefer it to JPG? The How-To Geek Guide to Audio Editing: The Basics How To Boot 10 Different Live CDs From 1 USB Flash Drive The 20 Best How-To Geek Linux Articles of 2010 Arctic Theme for Windows 7 Gives Your Desktop an Icy Touch Install LibreOffice via PPA and Receive Auto-Updates in Ubuntu Creative Portraits Peek Inside the Guts of Modern Electronics Scenic Winter Lane Wallpaper to Create a Relaxing Mood Access Your Web Apps Directly Using the Context Menu in Chrome The Deep – Awesome Use of Metal Objects as Deep Sea Creatures [Video]

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  • Possible to make mysql server both master and slave?

    - by Amy Anuszewski
    I am getting ready to move a database from one server to another. In order to reduce downtime for the client, I am wondering if it would be possible for me to turn on replication and give it time to replicate fully, then just point the customer to the new server. The issue I have is that the server I'm moving to has existing, active databases for other customers. And, the server I'm moving from has other active customers who will not be moving at this time. Is this even possible? If so, how do I configure the server I am moving from and the one I am moving to?

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  • PASS: The Legal Stuff

    - by Bill Graziano
    I wanted to give a little background on the legal status of PASS.  The Professional Association for SQL Server (PASS) is an American corporation chartered in the state of Illinois.  In America a corporation has to be chartered in a particular state.  It has to abide by the laws of that state and potentially pay taxes to that state.  Our bylaws and actions have to comply with Illinois state law and United States law.  We maintain a mailing address in Chicago, Illinois but our headquarters is currently in Vancouver, Canada. We have roughly a dozen people that work in our Vancouver headquarters and 4-5 more that work remotely on various projects.  These aren’t employees of PASS.  They are employed by a management company that we hire to run the day to day operations of the organization.  I’ll have more on this arrangement in a future post. PASS is a non-profit corporation.  The term non-profit and not-for-profit are used interchangeably.  In a for-profit corporation (or LLC) there are owners that are entitled to the profits of a company.  In a non-profit there are no owners.  As a non-profit, all the money earned by the organization must be retained or spent.  There is no money that flows out to shareholders, owners or the board of directors.  Any money not spent in furtherance of our mission is retained as financial reserves. Many non-profits apply for tax exempt status.  Being tax exempt means that an organization doesn’t pay taxes on its profits.  There are a variety of laws governing who can be tax exempt in the United States.  There are many professional associations that are tax exempt however PASS isn’t tax exempt.  Because our mission revolves around the software of a single company we aren’t eligible for tax exempt status. PASS was founded in the late 1990’s by Microsoft and Platinum Technologies.  Platinum was later purchased by Computer Associates. As the founding partners Microsoft and CA each have two seats on the Board of Directors.  The other six directors and three officers are elected as specified in our bylaws. As a non-profit, our bylaws layout our governing practices.  They must conform to Illinois and United States law.  These bylaws specify that PASS is governed by a Board of Directors elected by the membership with two members each from Microsoft and CA.  You can find our bylaws as well as a proposed update to them on the governance page of the PASS web site. The last point that I’d like to make is that PASS is completely self-funded.  All of our $4 million in revenue comes from conference registrations, sponsorships and advertising.  We don’t receive any money from anyone outside those channels.  While we work closely with Microsoft we are independent of them and only derive a very small percentage of our revenue from them.

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  • Does an SMTP request contain host header information (or just the IP of the targeted SMTP server)?

    - by Olaf
    We are using an external commercial smtp server for our newsletters (sending them through .NET components), and they offer two smtp URLs - smtp.critsend.com and fast.critsend.com -, and the second one is reserved for sending singular emails, the first one for bulk. Using nslookup shows that both resolve to the same 4 IP addresses (fast.critsend.com being an Alias). Question: (how) is it possible for the smtp relay to distinguish between different names? Is there something in the headers that can be compared to host headers in http protocol (I didn't find any intelligible information for a non-sysadmins)? The reason I'm asking is because we would like to use one of the IPs in our newsletter script (which works) rather than a name (in order to save DNS requests), and we are wondering about potential problems.

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  • (Abstract) Game engine design

    - by lukeluke
    I am writing a simple 2D game (for mobile platforms) for the first time. From an abstract point of view, i have the main player controlled by the human, the enemies, elments that will interact with the main player, other living elements that will be controlled by a simple AI (both enemies and non-enemies). The human player will be totally controlled by the player, the other actors will be controlled by AI. So i have a class CActor and a class CActorLogic to start with. I would define a CActor subclass CHero (the main player controlled with some input device). This class will probably implement some type of listener, in order to capture input events. The other players controlled by the AI will be probably a specific subclass of CActor (a subclass per-type, obviously). This seems to be reasonable. The CActor class should have a reference to a method of CActorLogic, that we will call something like CActorLogic::Advance() or similar. Actors should have a visual representation. I would introduce a CActorRepresentation class, with a method like Render() that will draw the actor (that is, the right frame of the right animation). Where to change the animation? Well, the actor logic method Advance() should take care of checking collisions and other things. I would like to discuss the design of a game engine (actors, entities, objects, messages, input handling, visualization of object states (that is, rendering, sound output and so on)) but not from a low level point of view, but from an high level point of view, like i have described above. My question is: is there any book/on line resource that will help me organize things (using an object oriented approach)? Thanks

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  • faking NAT with a VMware distributed switch across multiple hosts

    - by romant
    I need to construct a NAT for certain machines within the network. Wish to do this with dvSwitch - as it seems the logical way of attacking the problem as in this scenario there's just under 30 hosts. In order for the NAT'ed VM's to have access to the 'real' network. I am providing a 'router' VM, which will have access to the WAN/outside network, and also act as the DHCP server for the NAT'ed machines. Problem Space When the machines connected to the NAT interface and the router are on the same host, then they get an IP from the router VM, and work perfectly (routed outside). Unfortunately machines on other Hosts that are connected to the dvSwitch do not get an IP and further tcpdump shows no network data getting through across the hosts within the dvSwitch. Has anyone achieved a NAT solution using a dvSwitch before that they could share?! Thank you. EDIT: Including the diagram.

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  • Can't get sprite to rotate correctly?

    - by rphello101
    I'm attempting to play with graphics using Java/Slick 2d. I'm trying to get my sprite to rotate to wherever the mouse is on the screen and then move accordingly. I figured the best way to do this was to keep track of the angle the sprite is at since I have to multiply the cosine/sine of the angle by the move speed in order to get the sprite to go "forwards" even if it is, say, facing 45 degrees in quadrant 3. However, before I even worry about that, I'm having trouble even getting my sprite to rotate in the first place. Preliminary console tests showed that this code worked, but when applied to the sprite, it just kind twitches. Anyone know what's wrong? int mX = Mouse.getX(); int mY = HEIGHT - Mouse.getY(); int pX = sprite.x; int pY = sprite.y; int tempY, tempX; double mAng, pAng = sprite.angle; double angRotate=0; if(mX!=pX){ tempY=pY-mY; tempX=mX-pX; mAng = Math.toDegrees(Math.atan2(Math.abs((tempY)),Math.abs((tempX)))); if(mAng==0 && mX<=pX) mAng=180; } else{ if(mY>pY) mAng=270; else mAng=90; } //Calculations if(mX<pX&&mY<pY){ //If in Q2 mAng = 180-mAng; } if(mX<pX&&mY>pY){ //If in Q3 mAng = 180+mAng; } if(mX>pX&&mY>pY){ //If in Q4 mAng = 360-mAng; } angRotate = mAng-pAng; sprite.angle = mAng; sprite.image.setRotation((float)angRotate);

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  • How To Capture Screenshot Of Logon Screen In Windows 7?

    - by Gopinath
    There are plenty of freeware’s and paid applications that lets you capture screenshots. But none of them let you grab screenshot of Logon screen. In order to capture the screenshots of Logon screen we either had to use a Digital Camera and take a photo or run Windows in a virtual environment and capture screenshot.  Is there any other simple and easy way to grab Logon screenshots in Windows 7? Windows 7 Login Camera is a nice freeware that lets you capture screenshots of Logon screen very easily. To grab the screenshots install the application, lock the screen by pressing CTRL + L and use ease of access button located on the bottom left side. Windows 7 Login Camera launches and allows you save the captured screen on desired location. This handy tool is developed by deviantart.com website user yvidhiatama  and it’s compatible with all the 32bit version of Windows 7. Download Windows 7 Login Camera This article titled,How To Capture Screenshot Of Logon Screen In Windows 7?, was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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  • Apache configuration: choose a site to display according to visitor's IP address

    - by user64294
    Hi all. I would like to set a special configuration in our apache web server. I would like to display sites to the users according their IP addresses. We plan to upgrade our web sites. During the upgrade we'll put a maintenance site: so all the users which will connect to our web sites will get this site. but in order to test the upgrade i need to set apache to let only my IP address to access to asked site. If my IP address is a.b.c.d and if i ask for test_dot_com i want to see it. but all other users, having a different IP address, should get the maintenane site even if they look for test_dot_com. Is there a way to do this? PS: sorry As i'm a new user i can't use more than one link. so test_dot_com = test.com Thank you.

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  • Access Methods to a computer Using MAC Address

    - by Dimal Chandrasiri
    I have my own wifi network at home & recently when I checked the active clients on the wifi I found out the there is one active client. Router shows the MAC address of this client and I want to Access this computer in order to let him know that he's doing a wrong thing. I dont intent to do any harm to his data. I just want to know a method to send him a message saying "Buy you own wifi". How can I achieve this using a windows 8 computer. Is there any specific softwares that I can use or will the netsend command do the trick! Thank you.

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  • Replacing files in a folder structure with files from an unsorted folder

    - by Andrew
    I have over 50,000 PDFs organized into folders in a file called PDFACT. I needed to compress these files so I ran them through Adobe to batch compress them and this worked—except Adobe could only output the files without their folder structure. So basically I have 50,000 PDFs set up in a folder with hundreds of subfolders, and everything was organized. I ended up with one folder with 50,000 compressed PDFs in it, just in alphabetical order. Somehow I need to replace all the orginal PDFs with their compressed copies. Let me give an example: In the folder PDFACT we have the following file: C:\PDFACT\BIG DINNER\BILL\NEWESTBILL.PDF … and in the output folder that Adobe created we have just: C:\COMPRESSED_PDF_FOLDER\NEWESTBILL.PDF This copy is smaller then the one in PDFACT and has the same name but it is just lumped in with every other PDF. The folder structure and subfolders are gone. Is there any way to replace all the larger uncompressed PDFS inside the orginal folder structure with their now compressed counterparts?

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  • Script/tool to import series of snapshots, each being a new revision, into Subversion, populating source tree?

    - by Rob
    I've developed code locally and taken a fairly regular snapshot whenever I reach a significant point in development, e.g. a working build. So I have a long-ish list of about 40 folders, each folder being a snapshot e.g. in ascending date YYYYMMDD order, e.g.:- 20100523 20100614 20100721 20100722 20100809 20100901 20101001 20101003 20101104 20101119 20101203 20101218 20110102 I'm looking for a script to import each of these snapshots as a new subversion revision to the source tree. The end result being that the HEAD revision is the same as the last snapshot, and other revisions are as numbered. Some other requirements: that the HEAD revision is not cumulative of the previous snapshots, i.e., files that appeared in older snapshots but which don't appear in later ones (e.g. due to refactoring etc.) should not appear in the HEAD revision. meanwhile, there should be continuity between files that do persist between snapshots. Subversion should know that there are previous versions of these files and not treat them as brand new files within each revision. Some background about my aim: I need to formally revision control this work rather than keep local private snapshot copies. I plan to release this work as open source, so version controlling would be highly recommended I am evaluating some of the current popular version control systems (Subversion and GIT) BUT I definitely need a working solution in Subversion. I'm not looking to be persuaded to use one particular tool, I need a solution for each tool I am considering as I would also like a solution in GIT (I will post an answer separately for GIT so separate camps of folks who have expertise in GIT and Subversion will be able to give focused answers on one or the other). The same question but for GIT: Script/tool to import series of snapshots, each being a new edition, into GIT, populating source tree? An outline answer for Subversion in stackoverflow.com but not enough specifics about the script: what commands to use, code to check valid scenarios if necessary - i.e. a working script basically. http://stackoverflow.com/questions/2203818/is-there-anyway-to-import-xcode-snapshots-into-a-new-svn-repository

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  • vector rotations for branches of a 3d tree

    - by freefallr
    I'm attempting to create a 3d tree procedurally. I'm hoping that someone can check my vector rotation maths, as I'm a bit confused. I'm using an l-system (a recursive algorithm for generating branches). The trunk of the tree is the root node. It's orientation is aligned to the y axis. In the next iteration of the tree (e.g. the first branches), I might create a branch that is oriented say by +10 degrees in the X axis and a similar amount in the Z axis, relative to the trunk. I know that I should keep a rotation matrix at each branch, so that it can be applied to child branches, along with any modifications to the child branch. My questions then: for the trunk, the rotation matrix - is that just the identity matrix * initial orientation vector ? for the first branch (and subsequent branches) - I'll "inherit" the rotation matrix of the parent branch, and apply x and z rotations to that also. e.g. using glm::normalize; using glm::rotateX; using glm::vec4; using glm::mat4; using glm::rotate; vec4 vYAxis = vec4(0.0f, 1.0f, 0.0f, 0.0f); vec4 vInitial = normalize( rotateX( vYAxis, 10.0f ) ); mat4 mRotation = mat4(1.0); // trunk rotation matrix = identity * initial orientation vector mRotation *= vInitial; // first branch = parent rotation matrix * this branches rotations mRotation *= rotate( 10.0f, 1.0f, 0.0f, 0.0f ); // x rotation mRotation *= rotate( 10.0f, 0.0f, 0.0f, 1.0f ); // z rotation Are my maths and approach correct, or am I completely wrong? Finally, I'm using the glm library with OpenGL / C++ for this. Is the order of x rotation and z rotation important?

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  • Ray Tracing concers: Efficient Data Structure and Photon Mapping

    - by Grieverheart
    I'm trying to build a simple ray tracer for specific target scenes. An example of such scene can be seen below. I'm concerned as to what accelerating data structure would be most efficient in this case since all objects are touching but on the other hand, the scene is uniform. The objects in my ray tracer are stored as a collection of triangles, thus I also have access to individual triangles. Also, when trying to find the bounding box of the scene, how should infinite planes be handled? Should one instead use the viewing frustum to calculate the bounding box? A few other questions I have are about photon mapping. I've read the original paper by Jensen and many more material. In the compact data structure for the photon they introduce, they store photon power as 4 chars, which from my understanding is 3 chars for color and 1 for flux. But I don't understand how 1 char is enough to store a flux of the order of 1/n, where n is the number of photons (I'm also a bit confused about flux vs power). The other question about photon mapping is, if it would be more efficient in my case to store photons per object (or even per Object's triangle) instead of using a balanced kd-tree. Also, same question about bounding box of the scene but for photon mapping. How should one find a bounding box from the pov of the light when infinite planes are involved?

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  • Conflict Minerals - Design to Compliance

    - by C. Chadwick
    Dr. Christina  Schröder - Principal PLM Consultant, Enterprise PLM Solutions EMEA What does the Conflict Minerals regulation mean? Conflict Minerals has recently become a new buzz word in the manufacturing industry, particularly in electronics and medical devices. Known as the "Dodd-Frank Section 1502", this regulation requires SEC listed companies to declare the origin of certain minerals by 2014. The intention is to reduce the use of tantalum, tungsten, tin, and gold which originate from mines in the Democratic Republic of Congo (DRC) and adjoining countries that are controlled by violent armed militia abusing human rights. Manufacturers now request information from their suppliers to see if their raw materials are sourced from this region and which smelters are used to extract the metals from the minerals. A standardized questionnaire has been developed for this purpose (download and further information). Soon, even companies which are not directly affected by the Conflict Minerals legislation will have to collect and maintain this information since their customers will request the data from their suppliers. Furthermore, it is expected that the public opinion and consumer interests will force manufacturers to avoid the use of metals with questionable origin. Impact for existing products Several departments are involved in the process of collecting data and providing conflict minerals compliance information. For already marketed products, purchasing typically requests Conflict Minerals declarations from the suppliers. In order to address requests from customers, technical operations or product management are usually responsible for keeping track of all parts, raw materials and their suppliers so that the required information can be provided. For complex BOMs, it is very tedious to maintain complete, accurate, up-to-date, and traceable data. Any product change or new supplier can, in addition to all other implications, have an effect on the Conflict Minerals compliance status. Influence on product development  It makes sense to consider compliance early in the planning and design of new products. Companies should evaluate which metals are needed or contained in supplier parts and if these could originate from problematic sources. The answer influences the cost and risk analysis during the development. If it is known early on that a part could be non-compliant with respect to Conflict Minerals, alternatives can be evaluated and thus costly changes at a later stage can be avoided. Integrated compliance management  Ideally, compliance data for Conflict Minerals, but also for other regulations like REACH and RoHS, should be managed in an integrated supply chain system. The compliance status is directly visible across the entire BOM at any part level and for the finished product. If data is missing, a request to the supplier can be triggered right away without having to switch to another system. The entire process, from identification of the relevant parts, requesting information, handling responses, data entry, to compliance calculation is fully covered end-to-end while being transparent for all stakeholders. Agile PLM Product Governance and Compliance (PG&C) The PG&C module extends Agile PLM with exactly this integrated functionality. As with the entire Agile product suite, PG&C can be configured according to customer requirements: data fields, attributes, workflows, routing, notifications, and permissions, etc… can be quickly and easily tailored to a customer’s needs. Optionally, external databases can be interfaced to query commercially available sources of Conflict Minerals declarations which obviates the need for a separate supplier request in many cases. Suppliers can access the system directly for data entry through a special portal. The responses to the standard EICC-GeSI questionnaire can be imported by the supplier or internally. Manual data entry is also supported. A set of compliance-specific dashboards and reports complement the functionality Conclusion  The increasing number of product compliance regulations, for which Conflict Minerals is just one example, requires companies to implement an efficient data and process management in this area. Consumer awareness in this matter increases as well so that an integrated system from development to production also provides a competitive advantage. Follow this link to learn more about Agile's PG&C solution

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  • @CodeStock 2012 Review: Leon Gersing ( @Rubybuddha ) - "You"

    "YOU"Speaker: Leon GersingTwitter: @Rubybuddha Site: http://about.me/leongersing I honestly had no idea what I was getting in to when I sat down in to this session. I basically saw the picture of the speaker and knew that it would be a good session. I was completely wrong; it was the BEST SESSION of CodeStock 2012.  In fact it was so good, I texted another coworker attending the conference to get over and listen to Leon. Leon took on the concept of growth in the software development community. He specifically referred David Hansson in his ability to stick to his beliefs when the development community thought that he was crazy for creating Ruby on Rails. If you do not know this story Ruby on Rails is one of the fastest growing web languages today. In addition, he also touched on the flip side of this argument in that we must be open to others ideas and not discard them so quickly because we all come from differing perspectives and can add value to a project/team/community. This session left me with two very profound concepts/quotes: “In order to learn you must do it badly in front of a crowed and fail.” - @Rubybuddha I can look back on my career so far and say that he is correct; I think I have learned the most after failing, especially when I achieved this failure in front of other. “Experts must be able to fail.” - @Rubybuddha I think we can all learn from our own mistakes but we can also learn from others. When respected experts fail it is a great learning opportunity for the entire team as well as the person who failed. When expert admit mistakes and how they worked through them can be great learning tools for other developers so that they know how to avoid specific scenarios and if they do become stuck in the same issue they will know how to properly work their way out of them.

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  • Accessing hardware via USB by proprietary windows software using Wine

    - by Carlos Eugenio Thompson Pinzón
    I have this proprietary software that access some hardware using USB. Over a year ago I tried to install it on a Ubuntu OS using Wine (the program is written for Windows). The UI seemed to work just fine but it had no access to the USB port. Back then I had to license a Windows copy in order to get the job done. Now, that Windows version we where using is deprecated and it is not longer available and available versions cost trice as much. So it is time to give Linux another try. How can I ensure that the USB is available for a Wine application? Neither the application nor the hardware install any driver, the app just pool all available USB drivers and make a handshake if it recognizes that the hardware is present. I want to minimize the test cases before abandoning Linux one more time. Update I've just tried again (with the hope an upgrade was made from last year), and it is not working. The proprietary windows app is not finding the hardware.

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