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• Firmware/driver for Broadcom wifi card, PowerBook G4 running Ubuntu 12.04 [duplicate]

  - by user107831

  This question already has an answer here: How to Install Broadcom Wireless Drivers 40 answers This is my first time working with Ubuntu (or Linux), so please be patient. I am running Ubuntu 12.04-powerpc "Precise Pangolin" on a Mac PowerBook G4 with 1.67GHz processor. The firmware/driver for the wifi card is missing. For reasons not worth explaining, I cannot physically plug the computer into the network. I have another computer, a MacBook Pro running OSX, from which I can download files and port them by USB thumb drive. The wifi card in the PowerBook G4 is by Broadcom. The chip is BCM4306, rev. 3. The PCI number is 14e4:4302. I have downloaded b43-fwcutter_015-14_powerpc.deb and dropped it into the Home folder on the Ubuntu machine. However, it will not install. When I double-click, it opens with Ubuntu SoftwareCenter, but the "Install" button is inactive: I can't click it. There's a message beside the inactive button saying, "An older version of 'b43-fwcutter' is available in your normal software channels. Only install this file if you trust the origin." If I "right-click" the .deb file and open with Archive Manager, it shows me the "DEBIAN" and "usr" folders, but I'm unsure what to do from there...and fairly certain this is not the right way to do things. Maybe I have the wrong version of b43-fwcutter for my machine/version of Ubuntu? The documentation for this problem is a mess. It refers to all sorts of out-of-date Ubuntu versions and to an array of different "cutter" and firmware files. Maybe I'd be able to figure this out if I were a more seasoned Ubuntu user, but I have no idea why Sofware Center won't let me do the install. I would be VERY grateful for an explanation of how to get the wifi card working on this machine again. Thank you!

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• Automated backups for Windows Azure SQL Database

  - by Greg Low

  One of the questions that I've often been asked is about how you can backup databases in Windows Azure SQL Database. What we have had access to was the ability to export a database to a BACPAC. A BACPAC is basically just a zip file that contains a bunch of metadata along with a set of bcp files for each of the tables in the database. Each table in the database is exported one after the other, so this does not produce a transactionally-consistent backup at a specific point in time. To get a transactionally-consistent copy, you need a database that isn't in use.The easiest way to get a database that isn't in use is to use CREATE DATABASE AS COPY OF. This creates a new database as a transactionally-consistent copy of the database that you are copying. You can then use the export options to get a consistent BACPAC created.Previously, I've had to automate this process by myself. Given there was also no SQL Agent in Azure, I used a job in my on-premises SQL Server to do this, using a linked server configuration.Now there's a much simpler way. Windows Azure SQL Database now supports an automated export function. On the Configuration tab for the database, you need to enable the Automated Export function. You can configure how often the operation is performed for you, and which storage account will be used for the backups.It's important to consider the cost impacts of this as well. You are charged for how ever many databases are on your server on a given day. So if you enable a daily backup, you will double your database costs. Do not schedule the backups just before midnight UTC, as that could cause you to have three databases each day instead of one.This is a much needed addition to the capabilities. Scott Guthrie also posted about some other notable changes today, including a preview of a new premium offering for SQL Database. In addition to the Web and Business editions, there will now be a Premium edition that has reserved (rather than shared) resources. You can read about it all in Scott's post here: http://weblogs.asp.net/scottgu/archive/2013/07/23/windows-azure-july-updates-sql-database-traffic-manager-autoscale-virtual-machines.aspx

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• Walkthrough: Scheduling jobs using Quartz.net &ndash; Part 1: What is Quartz.Net?

  - by Tarun Arora

  Quartz.NET is a full-featured, open source enterprise job scheduling system written in .NET platform that can be used from smallest apps to large scale enterprise systems. What is the problem that we trying to address? I want to schedule the execution of a task but only when something happens. Let’s call that something a trigger, so... if the trigger is met => execute the task. Sounds simple, why not use windows task scheduler for this? Well, windows task scheduler is great for tasks where the trigger can be easily defined. With windows task scheduler will you be able to schedule a task to run on every working day according to the UK calendar (exclude all weekends & bank holidays) without either writing the logic for day check in the task or a wrapper script calling into the task. The task should just contain the execution logic and should not have anything to do with the schedule for execution; Quartz.net allows you to achieve this and lots more. A quartz.net trigger gives you the flexibility for task invocation based on the following triggers, 1. at a certain time of day (to the millisecond) 2. on certain days of the week 3. on certain days of the month 4. on certain days of the year 5. not on certain days listed within a registered Calendar (such as business holidays) 6. repeated a specific number of times 7. repeated until a specific time/date 8. repeated indefinitely 9. repeated with a delay interval Did 8 – repeat indefinitely just ring a bell? I’ll be covering that in the future post. Using Quartz.net as a windows service You can have Quartz.net run as a standalone instance within its own .NET virtual machine instance via .NET Remoting. Let’s take a look at typical application architecture. In the figure below, I have the application tier set up on Machine 1, database set up on Machine 2 and Quartz.net set up on Machine 3 which is normally the architecture for most (if not all) enterprise applications. Figure 1 -  Typical Application architecture while using Quartz.net as a windows service What other options do I have if I don’t want to use Quartz.net? Quartz.net is just one of the many job scheduling services. Have a look at this comprehensive list of free and paid enterprise job scheduling software along with their feature comparison. http://en.wikipedia.org/wiki/List_of_job_scheduler_software This was first in the series of posts on enterprise scheduling using Quartz.net, in the next post I’ll be covering how to Install Quartz.net as a windows service. Thank you for taking the time out and reading this blog post. If you enjoyed the post, remember to subscribe to http://feeds.feedburner.com/TarunArora. Stay tuned!

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• Perfomance of 8 bit operations on 64 bit architechture

  - by wobbily_col

  I am usually a Python / Database programmer, and I am considering using C for a problem. I have a set of sequences, 8 characters long with 4 possible characters. My problem involves combining sets of these sequences and filtering which sets match a criteria. The combinations of 5 run into billions of rows and takes around an hour to run. So I can represent each sequence as 2 bytes. If I am working on a 64 bit architechture will I gain any advantage by keeping these data structures as 2 bytes when I generate the combinations, or will I be as well storing them as 8 bytes / double ? (64 bit = 8 x 8) If I am on a 64 bit architecture, all registers will be 64 bit, so in terms of operations that shouldn´t be any faster (please correct me if I am wrong). Will I gain anything from the smaller storage requirements - can I fit more combinations in memory, or will they all take up 64 bits anyway? And finally, am I likley to gain anything coding in C. I have a first version, which stores the sequence as a small int in a MySQL database. It then self joins the tabe to itself a number of times in order to generate all the possible combinations. The performance is acceptable, depending on how many combinations are generated. I assume the database must involve some overhead.

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• Synaptics drivers are not loading on Kubuntu 13.10 on Dell Vostro 2420

  - by Alok Singh Mahor

  I freshly installed Kubuntu 13.10, 32 bit version on newly purchased Dell Vostro 2420. everything is working fine except scrolling and multitouch features through touchpad. I am able to change position of cursor using touchpad and able to tap (single click and double click) but scrolling is not working I tried to find out solution by searching on google but could not find proper solution to load synaptics drivers. i am listing some details: Laptop: Dell Vostro 2420 Linux Kernel version and distribution: 3.11.0-12-generic, Kubuntu 13.10 output of xinput list is ? Virtual core pointer id=2 [master pointer (3)] ? ? Virtual core XTEST pointer id=4 [slave pointer (2)] ? ? PS/2 Generic Mouse id=12 [slave pointer (2)] ? Virtual core keyboard id=3 [master keyboard (2)] ? Virtual core XTEST keyboard id=5 [slave keyboard (3)] ? Power Button id=6 [slave keyboard (3)] ? Video Bus id=7 [slave keyboard (3)] ? Power Button id=8 [slave keyboard (3)] ? Sleep Button id=9 [slave keyboard (3)] ? Laptop_Integrated_Webcam_HD id=10 [slave keyboard (3)] ? AT Translated Set 2 keyboard id=11 [slave keyboard (3)] ? Dell WMI hotkeys id=13 [slave keyboard (3)] Output of synclient -l is Couldn't find synaptics properties. No synaptics driver loaded? output of lshw is at http://paste.ubuntu.com/6645687/ xserver log and dmesg dont have trace of synaptics kindly tell me how to troubleshoot this problem.

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• Advanced Record-Level Business Intelligence with Inner Queries

  - by gt0084e1

  While business intelligence is generally applied at an aggregate level to large data sets, it's often useful to provide a more streamlined insight into an individual records or to be able to sort and rank them. For instance, a salesperson looking at a specific customer could benefit from basic stats on that account. A marketer trying to define an ideal customer could pull the top entries and look for insights or patterns. Inner queries let you do sophisticated analysis without the overhead of traditional BI or OLAP technologies like Analysis Services. Example - Order History Constancy Let's assume that management has realized that the best thing for our business is to have customers ordering every month. We'll need to identify and rank customers based on how consistently they buy and when their last purchase was so sales & marketing can respond accordingly. Our current application may not be able to provide this and adding an OLAP server like SSAS may be overkill for our needs. Luckily, SQL Server provides the ability to do relatively sophisticated analytics via inner queries. Here's the kind of output we'd like to see. Creating the Queries Before you create a view, you need to create the SQL query that does the calculations. Here we are calculating the total number of orders as well as the number of months since the last order. These fields might be very useful to sort by but may not be available in the app. This approach provides a very streamlined and high performance method of delivering actionable information without radically changing the application. It's also works very well with self-service reporting tools like Izenda. SELECT CustomerID,CompanyName, ( SELECT COUNT(OrderID) FROM Orders WHERE Orders.CustomerID = Customers.CustomerID ) As Orders, DATEDIFF(mm, ( SELECT Max(OrderDate) FROM Orders WHERE Orders.CustomerID = Customers.CustomerID) ,getdate() ) AS MonthsSinceLastOrder FROM Customers Creating Views To turn this or any query into a view, just put CREATE VIEW AS before it. If you want to change it use the statement ALTER VIEW AS. Creating Computed Columns If you'd prefer not to create a view, inner queries can also be applied by using computed columns. Place you SQL in the (Formula) field of the Computed Column Specification or check out this article here. Advanced Scoring and Ranking One of the best uses for this approach is to score leads based on multiple fields. For instance, you may be in a business where customers that don't order every month require more persistent follow up. You could devise a simple formula that shows the continuity of an account. If they ordered every month since their first order, they would be at 100 indicating that they have been ordering 100% of the time. Here's the query that would calculate that. It uses a few SQL tricks to make this happen. We are extracting the count of unique months and then dividing by the months since initial order. This query will give you the following information which can be used to help sales and marketing now where to focus. You could sort by this percentage to know where to start calling or to find patterns describing your best customers. Number of orders First Order Date Last Order Date Percentage of months order was placed since last order. SELECT CustomerID, (SELECT COUNT(OrderID) FROM Orders WHERE Orders.CustomerID = Customers.CustomerID) As Orders, (SELECT Max(OrderDate) FROM Orders WHERE Orders.CustomerID = Customers.CustomerID) AS LastOrder, (SELECT Min(OrderDate) FROM Orders WHERE Orders.CustomerID = Customers.CustomerID) AS FirstOrder, DATEDIFF(mm,(SELECT Min(OrderDate) FROM Orders WHERE Orders.CustomerID = Customers.CustomerID),getdate()) AS MonthsSinceFirstOrder, 100*(SELECT COUNT(DISTINCT 100*DATEPART(yy,OrderDate) + DATEPART(mm,OrderDate)) FROM Orders WHERE Orders.CustomerID = Customers.CustomerID) / DATEDIFF(mm,(SELECT Min(OrderDate) FROM Orders WHERE Orders.CustomerID = Customers.CustomerID),getdate()) As OrderPercent FROM Customers

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• Is there an excuse for short variable names?

  - by KChaloux

  This has become a large frustration with the codebase I'm currently working in; many of our variable names are short and undescriptive. I'm the only developer left on the project, and there isn't documentation as to what most of them do, so I have to spend extra time tracking down what they represent. For example, I was reading over some code that updates the definition of an optical surface. The variables set at the start were as follows: double dR, dCV, dK, dDin, dDout, dRin, dRout dR = Convert.ToDouble(_tblAsphere.Rows[0].ItemArray.GetValue(1)); dCV = convert.ToDouble(_tblAsphere.Rows[1].ItemArray.GetValue(1)); ... and so on Maybe it's just me, but it told me essentially nothing about what they represented, which made understanding the code further down difficult. All I knew was that it was a variable parsed out specific row from a specific table, somewhere. After some searching, I found out what they meant: dR = radius dCV = curvature dK = conic constant dDin = inner aperture dDout = outer aperture dRin = inner radius dRout = outer radius I renamed them to essentially what I have up there. It lengthens some lines, but I feel like that's a fair trade off. This kind of naming scheme is used throughout a lot of the code however. I'm not sure if it's an artifact from developers who learned by working with older systems, or if there's a deeper reason behind it. Is there a good reason to name variables this way, or am I justified in updating them to more descriptive names as I come across them?

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• PHP Battle System for RPG game

  - by Jay

  I posted this a while ago on stackoverflow, they thought it would be better place here, I agree. Essentially I know what I want to accomplish, and I have something to the effect of what I want but I am not satisfied with it. Here's the problem. Each user has some states: STR (how hard they hit), DEF (dodging/blocking attacks), SPD (when they can strike), and STAMINA (basically their endurance in game, if this runs out they can no longer fight and lose) What I need is something like this: UserA Stats: STR: 1,000 DEF: 2500 SPD: 2000 (HP: 1000/1000) UserB Stats: STR: 1,500 DEF: 500 SPD: 4000 (HP: 1000/1000) Because the second user has double the speed, he lands twice the amount of hits on the first user, before he gets hit. Because he has less strength than the first users defence, he will do no, to little damage. This is how the battle would theoretically go: UserB strikes UserA for 0 damage UserB strikes UserA for 0 damage UserA strikes UserB for 500 damage UserB strikes UserA for 0 damage UserB strikes UserA for 0 damage UserA strikes UserB for 500 damage, and sends him to the hospital! I was using this code, which is buggy, and not efficient, I just need a better way to do this: http://pastebin.com/15LiQQuJ Oh, and if anyone has some good ideas on how to improve the concept that would be cool too! It's not that elaborate so I'll be thinking of all sorts of things to make it more dynamic. Thanks.

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• Loadbalancing Questions

  - by Van Holtz

  I have been learning networking for about 4 months. Wrote a single standalone Multiplayer server and succeeded with authoritative approach. Now I want to extend it by splitting the single server into clusters to allow even more players to log in to avoid latency issues. Now I have protyped the Loadbalancing server and its running pretty good so far. This is my architecture, I have a master server which acts as a proxy, every sub servers(chat, login, game) connect to the master server as well as all the clients. when a client connects, Client Request: Send Request - MS(Master) - Decides which SS(SubServer) to forward to - Forwards Request to SS - SS - Analyze Message - Send Response to MS - Decides which Client to forward to - Forwards Response to Client Well, it looks like its going through lots of stages. it takes double the time to process the message than a single server approach. i feel like my model isnt the best or i may be wrong. is there any better model or the one they use in professional games? I still want a Master-SubServer approach. I just want to clarify that I'm going in the right direction before writing all my codes. Thanks for any answer :)

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• Are web application usability issues equal to website usability issues?

  - by Kor

  I've been reading two books about web usability issues and tests (Rocket Surgery Made Easy¹ and Prioritizing Web Usability²) and they claim some strategies and typical problems about website usability and how to lead them. However, I want to do a web application, and I think I lost track of what I am trying to solve. These two books claim to work with raw websites (e-commerce, business sites, even intranet), but I'm not sure if everything about web usability is applicable to web application usability. They sure talk about always having available (and usable) the Back button, to focus on short information rather than big amounts of text, etc., but they could be inaccurate in deeper problems that may be easier (or just skippable) in regular websites. Has anybody some experience in this field and could tell me if both web applications and websites share their usability issues? Thanks in advance Edit: Quoting Wikipedia, a website is a collection of related web pages containing images, videos or other digital assets, and a web application is an application that is accessed over a network such as the Internet or an intranet. To sum up, both shows/lets you search/produce information but websites are "simple" in interaction and keep the classics of websites (one-click actions) and the other one is closer to desktop applications in the meaning of their uses and ways of interaction (double click, modal windows, asynchronous calls [to keep you in the same "environment" instead of reloading it] etc.). I don't know if this clarifies the difference. Edit 2: Quoting @Victor and myself, a website is anything running in your browser, but a web application is somewhat running in your browser that could be running in your desktop, with similar behaviors and features. Gmail is a web application that could replace Outlook. GDocs could replace Office. Grooveshark could replace your music player, etc.

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• Burg Custom Icons work only with specific themes

  - by el10780

  I have made a custom icon for burg loader for my Lenovo Recovery Partition.I have made 3 icons : large_qdrive.png (128 X 128 pixels) small_qdrive.png (24 X 24 pixels) grey_qdrive.png (128 x 128 pixels) The .png icons that I created I made them using gimp from a qdrive.ico file that I found in the Lenovo Recovery Partition. I transferred the icons to the /boot/burg/themes/icons folder and I added to the class list of the grey,large,small and the hover files the following lines : -qdrive { image = "$$/large_qdrive.png" } in the large file -qdrive { image = "$$/small_qdrive.png" } in the small file -qdrive { image = "$$/grey_qdrive.png" } in the grey file -qdrive { image = "$$/grey_qdrive.png:$$/large_qdrive.png" } in the hover file I ran sudo update-burg and after that I modified the following line in the burg.cfg file : menuentry "Windows 7 (loader) (on /dev/sda2)" --class windows --class os { to menuentry "Windows 7 (loader) (on /dev/sda2)" --class qdrive --class os { and I also tried to change the title for the Lenovo Recovery Partition,so I tried this as well: menuentry "Lenovo Recovery Partition (on /dev/sda2)" --class qdrive --class os { None of this tries enforced actually burg loader to use the custom icon that I made and I can't figure out why. I have to mention also that there are a few themes that I have installed in burg which actually are able to use the small_qdrive.png icon that I made,but all the others which use either the large_qdrive.png or the grey_qdrive.png weren't able to use the custom icons. I have double checked for typos in all the files that I have created or I modified,so I am pretty sure that I haven't misspelled anything. I have checked also the title of the custom icons that I made and neither of them have a typo. I have looked also if there are any other folder that the themes might use to retrieve the icons,but it seems that all of them except for **Fortune** theme,which I downloaded from OMG!UBUNTU,use the icons folder which is located in /boot/burg/themes/icons I tried to add the custom icons to the icons folder of the theme **Fortune**,but still nothing happened.

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• Procurement Community Live Chat December 13th on Implementing AME with Purchase Orders

  - by LuciaC

  Do you still have questions on setting up the Approval Management Engine (AME) for Purchase Orders after attending the AME Webcast? Or maybe you are new to this topic and need more information?  Don’t miss our Procurement Community Live Chat on December 13th from 7:00 am to 11:00 am EST. Proactive Support and Development will be available to answer questions.You can access the main Oracle Communities page at http://communities.oracle.com (If you are enrolled, the Procurement community will be listed on your left.   If you're not already enrolled in the Procurement community, you can do so by clicking on the link Edit Subscriptions). OR you can use these alternative steps:From "My Oracle Support" as follows:    Log into My Oracle Support.    Click on the 'Community' link at the top of the page.    Click in 'Find a Community' field and enter Procurement.    Double click on Procurement in the list.    Click on the 'Create a Community Post' button and submit your question.Then in the ‘Procurement Featured Discussions’ section, drill down on the following thread and post your question.  We are looking forward to hearing from you!

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• Setup and configure a MVC4 project for Cloud Service(web role) and SQL Azure

  - by MagnusKarlsson

  I aim at keeping this blog post updated and add related posts to it. Since there are a lot of these out there I link to others that has done kind of the same before me, kind of a blog-DRY pattern that I'm aiming for. I also keep all mistakes and misconceptions for others to see. As an example; if I hit a stacktrace I will google it if I don't directly figure out the reason for it. I will then probably take the most plausible result and try it out. If it fails because I misinterpreted the error I will not delete it from the log but keep it for future reference and for others to see. That way people that finds this blog can see multiple solutions for indexed stacktraces and I can better remember how to do stuff. To avoid my errors I recommend you to read through it all before going from start to finish.The steps:Setup project in VS2012. (msdn blog)Setup Azure Services (half of mpspartners.com blog)Setup connections strings and configuration files (msdn blog + notes)Export certificates.Create Azure package from vs2012 and deploy to staging (same steps as for production).Connections string error Set up the visual studio project:http://blogs.msdn.com/b/avkashchauhan/archive/2011/11/08/developing-asp-net-mvc4-based-windows-azure-web-role.aspx Then login in to Azure to setup the services:Stop following this guide at the "publish website" part since we'll be uploading a package.http://www.mpspartners.com/2012/09/ConfiguringandDeployinganMVC4applicationasaCloudServicewithAzureSQLandStorage/ When set up (connection strings for debug and release and all), follow this guide to set up the configuration files:http://msdn.microsoft.com/en-us/library/windowsazure/hh369931.aspxTrying to package our application at this step will generate the following warning:3>MvcWebRole1(0,0): warning WAT170: The configuration setting 'Microsoft.WindowsAzure.Plugins.Diagnostics.ConnectionString' is set up to use the local storage emulator for role 'MvcWebRole1' in configuration file 'ServiceConfiguration.Cloud.cscfg'. To access Windows Azure storage services, you must provide a valid Windows Azure storage connection string. Right click the web role under roles in solution manager and choose properties. Choose "Service configuration: Cloud". At "specify storage account credentials" we will copy/paste our account name and key from the Azure management platform.3.1 4. Right click Remote desktop Configuration and select certificate and export to file. We need to allow it in Portal manager.4.15 Now right click the cloud project and select package.5.1 Showing dialogue box. 5.2 Package success Now copy the path to the packaged file and go to management portal again. Click your web role and choose staging (or production). Upload. 5.3Tick the box about the single instance if that's what you want or you don't know what it means. Otherwise the following will happen (see image 4.6)5.4 Dialogue box When you have clicked the symbol for accept- button you will see the following screen with some green indicators down at the right corner. Click them if you want to see status.5.5 Information screen.5.6 "Failed to deploy application. The upload application has at least one role with only one instance. We recommend that you deploy at least two instances per role to ensure high availability in case one of the instances becomes unavailable. "To fix, go to step 5.4If you forgot to (or just didn't know you were supposed to) export your certificates. The following error will occur. Side note, the following thread suggests. To prevent: "Enable Remote Desktop for all roles" when right-clicking BIAB and choosing "Package". But in my case it was the not so present certificates. I fund the solution here.http://social.msdn.microsoft.com/Forums/en-US/dotnetstocktradersampleapplication/thread/0e94c2b5-463f-4209-86b9-fc257e0678cd5.75.8 Success! 5.9 Nice URL n' all. (More on that at another blog post).6. If you try to login and getWhen this error occurs many web sites suggest this is because you need:http://nuget.org/packages/Microsoft.AspNet.Providers.LocalDBOr : http://nuget.org/packages/Microsoft.AspNet.ProvidersBut it can also be that you don't have the correct setup for converting connectionstrings between your web.config to your debug.web.config(or release.web.config, whichever your using).Run as suggested in the "ordinary project in your solution. Go to the management portal and click update.

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• Is there an excuse for excessively short variable names?

  - by KChaloux

  This has become a large frustration with the codebase I'm currently working in; many of our variable names are short and undescriptive. I'm the only developer left on the project, and there isn't documentation as to what most of them do, so I have to spend extra time tracking down what they represent. For example, I was reading over some code that updates the definition of an optical surface. The variables set at the start were as follows: double dR, dCV, dK, dDin, dDout, dRin, dRout dR = Convert.ToDouble(_tblAsphere.Rows[0].ItemArray.GetValue(1)); dCV = convert.ToDouble(_tblAsphere.Rows[1].ItemArray.GetValue(1)); ... and so on Maybe it's just me, but it told me essentially nothing about what they represented, which made understanding the code further down difficult. All I knew was that it was a variable parsed out specific row from a specific table, somewhere. After some searching, I found out what they meant: dR = radius dCV = curvature dK = conic constant dDin = inner aperture dDout = outer aperture dRin = inner radius dRout = outer radius I renamed them to essentially what I have up there. It lengthens some lines, but I feel like that's a fair trade off. This kind of naming scheme is used throughout a lot of the code however. I'm not sure if it's an artifact from developers who learned by working with older systems, or if there's a deeper reason behind it. Is there a good reason to name variables this way, or am I justified in updating them to more descriptive names as I come across them?

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• Floating point undesireable in highly critical code?

  - by Kirt Undercoffer

  Question 11 in the Software Quality section of "IEEE Computer Society Real-World Software Engineering Problems", Naveda, Seidman, lists fp computation as undesirable because "the accuracy of the computations cannot be guaranteed". This is in the context of computing acceleration for an emergency braking system for a high speed train. This thinking seems to be invoking possible errors in small differences between measurements of a moving object but small differences at slow speeds aren't a problem (or shouldn't be), small differences between two measurements at high speed are irrelevant - can there be a problem with small roundoff errors during deceleration for an emergency braking system? This problem has been observed with airplane braking systems resulting in hydroplaning but could this actually happen in the context of a high speed train? The concern about fp errors seems to not be well-founded in this context. Any insight? The fp is used for acceleration so perhaps the concern is inching over a speed limit? But fp should be just fine if they use a double in whatever implementation language. The actual problem in the text states: During the inspection of the code for the emergency braking system of a new high speed train (a highly critical, real-time application), the review team identifies several characteristics of the code. Which of these characteristics are generally viewed as undesirable? The code contains three recursive functions (well that one is obvious). The computation of acceleration uses floating point arithmetic. All other computations use integer arithmetic. The code contains one linked list that uses dynamic memory allocation (second obvious problem). All inputs are checked to determine that they are within expected bounds before they are used.

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• Handling Types for Real and Complex Matrices in a BLAS Wrapper

  - by mga

  I come from a C background and I'm now learning OOP with C++. As an exercise (so please don't just say "this already exists"), I want to implement a wrapper for BLAS that will let the user write matrix algebra in an intuitive way (e.g. similar to MATLAB) e.g.: A = B*C*D.Inverse() + E.Transpose(); My problem is how to go about dealing with real (R) and complex (C) matrices, because of C++'s "curse" of letting you do the same thing in N different ways. I do have a clear idea of what it should look like to the user: s/he should be able to define the two separately, but operations would return a type depending on the types of the operands (R*R = R, C*C = C, R*C = C*R = C). Additionally R can be cast into C and vice versa (just by setting the imaginary parts to 0). I have considered the following options: As a real number is a special case of a complex number, inherit CMatrix from RMatrix. I quickly dismissed this as the two would have to return different types for the same getter function. Inherit RMatrix and CMatrix from Matrix. However, I can't really think of any common code that would go into Matrix (because of the different return types). Templates. Declare Matrix<T> and declare the getter function as T Get(int i, int j), and operator functions as Matrix *(Matrix RHS). Then specialize Matrix<double> and Matrix<complex>, and overload the functions. Then I couldn't really see what I would gain with templates, so why not just define RMatrix and CMatrix separately from each other, and then overload functions as necessary? Although this last option makes sense to me, there's an annoying voice inside my head saying this is not elegant, because the two are clearly related. Perhaps I'm missing an appropriate design pattern? So I guess what I'm looking for is either absolution for doing this, or advice on how to do better.

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• A Reusable Builder Class for .NET testing

  - by Liam McLennan

  When writing tests, other than end-to-end integration tests, we often need to construct test data objects. Of course this can be done using the class’s constructor and manually configuring the object, but to get many objects into a valid state soon becomes a large percentage of the testing effort. After many years of painstakingly creating builders for each of my domain objects I have finally become lazy enough to bother to write a generic, reusable builder class for .NET. To use it you instantiate a instance of the builder and configuring it with a builder method for each class you wish it to be able to build. The builder method should require no parameters and should return a new instance of the type in a default, valid state. In other words the builder method should be a Func<TypeToBeBuilt>. The best way to make this clear is with an example. In my application I have the following domain classes that I want to be able to use in my tests: public class Person { public string Name { get; set; } public int Age { get; set; } public bool IsAndroid { get; set; } } public class Building { public string Street { get; set; } public Person Manager { get; set; } } The builder for this domain is created like so: build = new Builder(); build.Configure(new Dictionary<Type, Func<object>> { {typeof(Building), () => new Building {Street = "Queen St", Manager = build.A<Person>()}}, {typeof(Person), () => new Person {Name = "Eugene", Age = 21}} }); Note how Building depends on Person, even though the person builder method is not defined yet. Now in a test I can retrieve a valid object from the builder: var person = build.A<Person>(); If I need a class in a customised state I can supply an Action<TypeToBeBuilt> to mutate the object post construction: var person = build.A<Person>(p => p.Age = 99); The power and efficiency of this approach becomes apparent when your tests require larger and more complex objects than Person and Building. When I get some time I intend to implement the same functionality in Javascript and Ruby. Here is the full source of the Builder class: public class Builder { private Dictionary<Type, Func<object>> defaults; public void Configure(Dictionary<Type, Func<object>> defaults) { this.defaults = defaults; } public T A<T>() { if (!defaults.ContainsKey(typeof(T))) throw new ArgumentException("No object of type " + typeof(T).Name + " has been configured with the builder."); T o = (T)defaults[typeof(T)](); return o; } public T A<T>(Action<T> customisation) { T o = A<T>(); customisation(o); return o; } }

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• How to Pin Any File to the Start Screen in Windows 8

  - by Taylor Gibb

  By default Windows 8 only allows you to pin a few file types to the Start Screen. Read on to find out how you can change that by editing the registry. How to Pin Any File to the Start Screen in Windows 8 Press the Win + R keyboard combination to open a run box, then type notepad and press enter. When notepad opens, paste the following into the new document: Windows Registry Editor Version 5.00 [HKEY_CLASSES_ROOT\*\shell\pintostartscreen] “MUIVerb”=”@shell32.dll,-51201″ “NeverDefault”=”" “Description”=”@shell32.dll,-51202″ “MultiSelectModel”=”Single” [HKEY_CLASSES_ROOT\*\shell\pintostartscreen\command] “DelegateExecute”=”{470C0EBD-5D73-4d58-9CED-E91E22E23282}” Then click on the File menu item and select save as… Before you go any further, change the Save as type to All Files. Then give your file a name ending in .reg and click Save. PinToStartHack.reg To use the hack, just double click on the .reg file you just created. When you are prompted about whether you want to continue, click Yes. Now you can pin any file to the Start Screen. Undo the Change If you ever wish to undo the change, press the Win + R keyboard combination and type regedit, then press enter. Then drill down into: HKEY_CLASSES_ROOT\*\shell\ Finally delete the pintostartscreen key. That’s all there is to it. How to Factory Reset Your Android Phone or Tablet When It Won’t Boot Our Geek Trivia App for Windows 8 is Now Available Everywhere How To Boot Your Android Phone or Tablet Into Safe Mode

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• The tale of how the PowerShell CmdLets got installed with Azure SDK 1.4

  - by Enrique Lima

  I installed the Azure SDK 1.4 while rebuilding my laptop and ran the installation for the Windows Azure Service Management PowerShell CmdLets. Kicked off the installation script for the WASM PowerShell CmdLets by locating the path to which WASM PowerShell CmdLets was deployed to. Double clicked the startHere command. It will then open the WASM installation dialog. Click Next. Click Next. Notice the red x next to the Azure SDK 1.3, the problem is I have SDK 1.4 Here is the workaround, I go back to the location of the deployed WASM sources. Go into the setup path, then scripts>dependencies>check. Now, locate the CheckAzureSDK.ps1 file, and right-click, then edit. This is the content in the ps1 file, it check for the specific version of the Azure SDK, in this case, it is looking for version 1.3.11133.0038. We need for it to check for version 1.4.20227.1419 Now, save your ps1 file, go back to the open WASM install dialog, and click rescan. This time it should pass, then click next. A Command prompt window will appear, click any key. This completes the installation, click Close.

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• Sources of NetBeans Gradle Plugin

  - by Geertjan

  Here is where you can find the sources of the latest and greatest NetBeans Gradle plugin: http://java.net/projects/nb-api-samples/sources/api-samples/show/versions/7.1/misc/GradleSupport To use it, download the sources above, open the sources into the IDE (which must be 7.1.1 or above), then you'll have a NetBeans module. Right-click it to run the module into a new instance of NetBeans IDE. In the Options window's Miscellaneous tab, there's a Gradle subtab for setting the Gradle location. In the New File dialog, in the Other category, you'll find a template named "Empty Gradle file". Make sure to name it "build" and to put it in the root directory of the application (by leaving the Folder field empty, you're specifying it should be created in the root directory). You'll then be able to expand the build.gradle file: Double-click a task to run it. When you open the file, it opens in the Groovy editor, if the Groovy editor is installed. When you make changes in the file, the list of tasks, shown above, is automatically recreated. It's at a really early stage of development and it would be great if developers out there would be interested in adding more features to it.

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• How can I assign actions to all my mouse buttons?

  - by Torben Gundtofte-Bruun

  I have a mouse with lots of buttons, but it's not a mainstream make like Logitech. For Windows, I have a driver that lets me assign actions like close-window (Ctrl+W) or next-tab (Ctrl+Tab), but I don't have a Linux driver. Since Linux is so flexible, I thought perhaps there is a general way to do this, regardless of brand? Update: Based on input from Cyrex, I installed and ran sudo apt-get install btnx which found several but not all mouse buttons. Found: left, right, wheel, wheelclick, thumb fwd, thumb back. Not found: wheel left, wheel right, thumb middle button. Vendor ID is 0x04d9, Model ID is 0xa015. Update 2: In SystemPrefsMouse there's a lightbulb icon for testing double-click speed. Every working button can turn the bulb on&off, but the missing buttons can't. It would seem that Ubuntu isn't aware of these buttons and thus doesn't register their clicks. I guess I need to hunt for a driver, though a mainstream mouse is probably the easier way.

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• When module calling gets ugly

  - by Pete

  Has this ever happened to you? You've got a suite of well designed, single-responsibility modules, covered by unit tests. In any higher-level function you code, you are (95% of the code) simply taking output from one module and passing it as input to the next. Then, you notice this higher-level function has turned into a 100+ line script with multiple responsibilities. Here is the problem. It is difficult (impossible) to test that script. At least, it seems so. Do you agree? In my current project, all of the bugs came from this script. Further detail: each script represents a unique solution, or algorithm, formed by using different modules in different ways. Question: how can you remedy this situation? Knee-jerk answer: break the script up into single-responsibility modules. Comment on knee-jerk answer: it already is! Best answer I can come up with so far: create higher-level connector objects which "wire" modules together in particular ways (take output from one module, feed it as input to another module). Thus if our script was: FooInput fooIn = new FooInput(1, 2); FooOutput fooOutput = fooModule(fooIn); Double runtimevalue = getsomething(fooOutput.whatever); BarInput barIn = new BarInput( runtimevalue, fooOutput.someOtherValue); BarOutput barOut = barModule(BarIn); It would become with a connector: FooBarConnectionAlgo fooBarConnector = new fooBarConnector(fooModule, barModule); FooInput fooIn = new FooInput(1, 2); BarOutput barOut = fooBarConnector(fooIn); So the advantage is, besides hiding some code and making things clearer, we can test FooBarConnectionAlgo. I'm sure this situation comes up a lot. What do you do?

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• forward motion car physics - gradual slow

  - by spartan2417

  Im having trouble creating realistic car movements in xna 4. Right now i have a car going forward and hitting a terminal velocity which is fine but when i release the up key i need to the car to slow down gradually and then come to a stop. Im pretty sure this is easy code but i cant seem to get it to work the code - update if (Keyboard.GetState().IsKeyDown(Keys.Up)) { double elapsedTime = gameTime.ElapsedGameTime.Milliseconds; CalcTotalForce(); Acceleration = Vector2.Divide(CalcTotalForce(), MASS); Velocity = Vector2.Add(Velocity, Vector2.Multiply(Acceleration, (float)(elapsedTime))); Position = Vector2.Add(Position, Vector2.Multiply(Velocity, (float)(elapsedTime))); } added functions public Vector2 CalcTraction() { //Traction force = vector direction * engine force return Vector2.Multiply(forwardDirection, ENGINE_FORCE); } public Vector2 CalcDrag() { //Drag force = constdrag * velocity * speed return Vector2.Multiply(Vector2.Multiply(Velocity, DRAG_CONST), Velocity.Y); } public Vector2 CalcRoll() { //roll force = const roll * velocity return Vector2.Multiply(Velocity, ROLL_CONST); } public Vector2 CalcTotalForce() { //total force = traction + (-drag) + (-rolling) return Vector2.Add(CalcTraction(), Vector2.Add(-CalcDrag(), -CalcRoll())); } anyone have any ideas?

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• Strategies for invoking subclass methods on generic objects

  - by Brad Patton

  I've run into this issue in a number of places and have solved it a bunch of different ways but looking for other solutions or opinions on how to address. The scenario is when you have a collection of objects all based off of the same superclass but you want to perform certain actions based only on instances of some of the subclasses. One contrived example of this might be an HTML document made up of elements. You could have a superclass named HTMLELement and subclasses of Headings, Paragraphs, Images, Comments, etc. To invoke a common action across all of the objects you declare a virtual method in the superclass and specific implementations in all of the subclasses. So to render the document you could loop all of the different objects in the document and call a common Render() method on each instance. It's the case where again using the same generic objects in the collection I want to perform different actions for instances of specific subclass (or set of subclasses). For example (an remember this is just an example) when iterating over the collection, elements with external links need to be downloaded (e.g. JS, CSS, images) and some might require additional parsing (JS, CSS). What's the best way to handle those special cases. Some of the strategies I've used or seen used include: Virtual methods in the base class. So in the base class you have a virtual LoadExternalContent() method that does nothing and then override it in the specific subclasses that need to implement it. The benefit being that in the calling code there is no object testing you send the same message to each object and let most of them ignore it. Two downsides that I can think of. First it can make the base class very cluttered with methods that have nothing to do with most of the hierarchy. Second it assumes all of the work can be done in the called method and doesn't handle the case where there might be additional context specific actions in the calling code (i.e. you want to do something in the UI and not the model). Have methods on the class to uniquely identify the objects. This could include methods like ClassName() which return a string with the class name or other return values like enums or booleans (IsImage()). The benefit is that the calling code can use if or switch statements to filter objects to perform class specific actions. The downside is that for every new class you need to implement these methods and can look cluttered. Also performance could be less than some of the other options. Use language features to identify objects. This includes reflection and language operators to identify the objects. For example in C# there is the is operator that returns true if the instance matches the specified class. The benefit is no additional code to implement in your object hierarchy. The only downside seems to be the lack of using something like a switch statement and the fact that your calling code is a little more cluttered. Are there other strategies I am missing? Thoughts on best approaches?

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• Calculating a child object's Position, Rotation and Scale values?

  - by Sergio Plascencia

  I am making my own game editor, but have encountered the following problem: I have two objects, A and B. A's initial values: Position: (3,3,3), Rotation: (45,10,0), Scale(1,2,2.5) B's initial values: Position: (1,1,1), Rotation: (10,34,18), Scale(1.5,2,1) If I now make B a child of A, I need to re-calculate the B's Position, Rotation and Scale relative to A such that it maintains its current position, rotation and scale in world coordinates. So B's position would now be (-2, -2, -2) since now A is its center and (-2, -2, -2) will keep B in the same position. I think I got the Position and scale figured out, but not rotation. So I opened Unity and ran the same example and I noticed that when making a child object, the child object did not move at all. but had its Position, Rotation and Scale values changed relative to the parent. For example: Unity (Parent Object "A"): Position: (0,0,0) Rotation: (45,10,0) Scale: (1,1,1) Unity (Child Object "B"): Position: (0,0,0) Rotation: (0,0,0) Scale: (1,1,1) When B becomes a child of A, it's rotation values become: X: -44.13605 Y: -14.00195 Z: 9.851074 If I plug the same rotation values into the B object in my editor, the object does not move at all. How did Unity arrive at those rotation values for the child? What are the calculations? If you can put all the equations for the Position, Rotation or Scale then I can double check I am doing it correctly but the Rotation is what I really need.

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