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  • What's the relationship between meta-circular interpreters, virtual machines and increased performance?

    - by Gomi
    I've read about meta-circular interpreters on the web (including SICP) and I've looked into the code of some implementations (such as PyPy and Narcissus). I've read quite a bit about two languages which made great use of metacircular evaluation, Lisp and Smalltalk. As far as I understood Lisp was the first self-hosting compiler and Smalltalk had the first "true" JIT implementation. One thing I've not fully understood is how can those interpreters/compilers achieve so good performance or, in other words, why is PyPy faster than CPython? Is it because of reflection? And also, my Smalltalk research led me to believe that there's a relationship between JIT, virtual machines and reflection. Virtual Machines such as the JVM and CLR allow a great deal of type introspection and I believe they make great use it in Just-in-Time (and AOT, I suppose?) compilation. But as far as I know, Virtual Machines are kind of like CPUs, in that they have a basic instruction set. Are Virtual Machines efficient because they include type and reference information, which would allow language-agnostic reflection? I ask this because many both interpreted and compiled languages are now using bytecode as a target (LLVM, Parrot, YARV, CPython) and traditional VMs like JVM and CLR have gained incredible boosts in performance. I've been told that it's about JIT, but as far as I know JIT is nothing new since Smalltalk and Sun's own Self have been doing it before Java. I don't remember VMs performing particularly well in the past, there weren't many non-academic ones outside of JVM and .NET and their performance was definitely not as good as it is now (I wish I could source this claim but I speak from personal experience). Then all of a sudden, in the late 2000s something changed and a lot of VMs started to pop up even for established languages, and with very good performance. Was something discovered about the JIT implementation that allowed pretty much every modern VM to skyrocket in performance? A paper or a book maybe?

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  • Thank you South Florida for a successful SPSouthFLA

    - by Leonard Mwangi
    I wanted to officially thank the organizers, speakers, volunteers and the attendees of SharePoint Saturday South Florida. Being the first event in South Florida the reception was phenomenon and the group of speakers from keynote by Joel Oleson to session’s speakers from well renowned speakers like John Holliday, Randy Disgrill, Richard Harbridge, Ameet Phadnis, Fabian Williams, Chris McNulty, Jaime Velez to organizers like Michael Hinckley amongst others. With my Business Intelligence (BI) presentation being on the last track of the day, I spent very quality time networking with these great guys and getting the insider scope on International SharePoint Community from Joel and his son which was mesmerizing. I had a very active audience to a point where we couldn’t accommodate all the contents within the 1hr allocated time because they were very engaged and wanted a deep dive session on news features like PowerPivot, enhancements on PerformancePoint, Excel Services amongst others in order to understand the business value and how SharePoint 2010 is making the self-service BI become a reality. These community events allows the attendees experience technology first hand and network with MVPs, authors, experts providing high quality educational sessions usually for free which is a reason to attend. I have made the slides for my session available for download for those interested http://goo.gl/VaH5x

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  • Exadata X3 Sales/Pre-Sales/Support Resell Rights Enablement Day

    - by mseika
    Dear Partner, Avnet and Oracle would like to invite you to a FREE Exadata X3 Sales/Pre-Sales/Support Resell Rights Enablement Day which is taking place on Wednesday 16th January 2013 at the Oracle London City offices in Moorgate. We will give you the opportunity to get an in depth understanding of how hardware and software is engineered to work together to create the power and scalability of Exadata. The session will focus on Oracle Exadata fundamentals, features, components and capabilities. The event will be a day long and will give you the opportunity to put any questions to the presenters that will help you understand how to spot an Exadata opportunity and position Exadata in an opportunity.   Register Now Register now or call our Hotline on 01925 856999. When Wednesday 16th January 2013 Duration: 9.30am to 17.00pm Where Oracle Corporation UK Ltd. One South PlaceLondon EC2M 2RB. For directionsplease see thelocation map.   Cost No charge Contact Us Avnet Technology Solutions LimitedClarity House103 Dalton AvenueBirchwood ParkWarringtonWA3 6YBUKT: 01925 856900 F: 01925 856901 E: [email protected] Or find us online:Avnet websiteLinkedInTwitterFacebook

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  • Two things I learned this week...

    - by noreply(at)blogger.com (Thomas Kyte)
    I often say "I learn something new about Oracle every day".  It really is true - there is so much to know about it, it is hard to keep up sometimes.Here are the two new things I learned - the first is regarding temporary tablespaces.  In the past - when people have asked "how can I shrink my temporary tablespace" I've said "create a new one that is smaller, alter your database/users to use this new one by default, wait a bit, drop the old one".  Actually I usually said first - "don't, it'll just grow again" but some people really wanted to make it smaller.Now, there is an easier way:http://docs.oracle.com/cd/E11882_01/server.112/e26088/statements_3002.htm#SQLRF53578Using alter tablespace temp shrink space .The second thing is just a little sqlplus quirk that I probably knew at one point but totally forgot.  People run into problems with &'s in sqlplus all of the time as sqlplus tries to substitute in for an &variable.  So, if they try to select '&hello world' from dual - they'll get:ops$tkyte%ORA11GR2> select '&hello world' from dual;Enter value for hello: old   1: select '&hello world' from dualnew   1: select ' world' from dual'WORLD------ worldops$tkyte%ORA11GR2> One solution is to "set define off" to disable the substitution (or set define to some other character).  Another oft quoted solution is to use chr(38) - select chr(38)||'hello world' from dual.  I never liked that one personally.  Today - I was shown another wayhttps://asktom.oracle.com/pls/apex/f?p=100:11:0::::P11_QUESTION_ID:4549764300346084350#4573022300346189787 ops$tkyte%ORA11GR2> select '&' || 'hello world' from dual;'&'||'HELLOW------------&hello worldops$tkyte%ORA11GR2>just concatenate '&' to the string, sqlplus doesn't touch that one!  I like that better than chr(38) (but a little less than set define off....)

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  • Best ways to collect location-based user input

    - by user359650
    I'm working on a website where users will be able to register and provide information about their location. In order to prevent users from inputting incorrect data, we don't want users to provide free-text information but instead choose from predefined values as much as possible. We believe there are 2 ways of providing those values: use an API to an external service provider or create your own local database. APIs Some resources: - https://developers.facebook.com/docs/reference/ads-api/get-autocomplete-data/ - http://developer.yahoo.com/geo/geoplanet/ Pros: -accuracy and completeness of data. -no maintenance related to update of data as this it taken care of by API provider. -easier/faster to get started (no need to create local database, just implement API). Cons: -degradation of performance when availability issues with external API. -outage due to changes to the external API (until your code is updated to reflect those changes). -lock-in with external provider. Local database Some resources: - http://developer.yahoo.com/geo/geoplanet/data/ - http://www.maxmind.com/app/geolitecity - http://download.geonames.org/export/dump/ Pros: -no external dependency: improved stability and performance. Cons: -more work to get started (you need to create the database and code to interact with it). -risks of inaccurate/incomplete data, either initially or over time. -more maintenance work to keep database up to date. Assuming the depth information requested from users is as follows: -country: interested in value. also used to narrow down list of regions. -region (state in the US, county in the UK...): not interested in value itself, only used to narrow down list of cities. -city: interested in value (which can be used to work out related region should we need regional statistics). -address: interested in value although OPTIONAL. Which option (whether API or local database) would you choose? What tips you would give for the implementation? What other resources can you share?

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  • How should developers handle subpar working conditions? [closed]

    - by ivar
    I have been working in my current job for less than a year and at the beginning didn't have the courage to say anything about the things that bothered me. Now I'm a bit fed up and need things to get better. The first problem is not random but I'll mention it anyway. We are running out of space so every new employee gets a smaller table. We are promised that the space problem will be fixed soon. Almost every employee has a different keyboard, mouse, headphones (if any). Mine are $10 keyboard, some random cheap mouse and some random crappy headphones with a mic. All these were used and dirty when I got them. The number of monitor is 1-3 and with different sizes. I have 2 nice monitors and can't complain but some are given 1 small monitor. When it's their first job they don't have the guts to ask for 2 even if most others have 2. Nobody seems to care too. Project manager asked if it's ok? He obviously said he can handle the 1 small one. Then the manager said you can go ask for 1 more. I'm watching this and think go and ask where? The company is trying to hire more people but is not doing much after the person has signed the contract. We are put in one room that is open to the hallway and it's super noisy. Almost like a zoo at times. Even if nobody is talking the crappy keyboards make too much noise. Is this normal? Am I too negative and should I just do my job with what I was given? Should I demand better things? Should the company have some system that everybody gets things in some price range?

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  • SQL Saturday Atlanta: Intro To Performance Tuning

    - by Mike Femenella
    I'm looking forward to speaking in Atlanta on the 24th, will be fun to get back down that way to visit with some friends and present two topics that I really enjoy. First, an introduction to performance tuning. Performance tuning is a very wide and deep topic and we're staying close to the surface. I direct this class for newbie sql users who have less than 2 years of experience. It's all the things I wish someone would have told me in my first 2 years about what to look for when the database was slow...or allegedly slow I should say. We'll cover using profiler to find slow performing queries and how to save the data off to a table as well as a tour of other features. The difference between clustered, non clustered and covering indexes. How to look at and understand an execution plan (at a high level) and finally the difference between a temp table and a table variable and what the implications are of using either one in your code. That pretty much takes up a full hour. Second presentation, Loading Data in Real Time. It's really a presentation about partitioning but with a twist that we used at work recently to solve a need to load some data quickly and put it into production with minimal downtime. We'll cover partition functions, schemes,$partition, merge, sys.partitions and show some examples of building a set of partitioned tables and using the switch statement to move it from one table to another. Finally we'll cover the differences in partitioning between 2005 and 2008. Hope to see you there! And if you read my blog please introduce yourself!

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  • How to limit click'n'drag movement to an area?

    - by Vexille
    I apologize for the somewhat generic title. I'm really don't have much clue about how to accomplish what I'm trying to do, which is making it harder even to research a possible solution. I'm trying to implement a path marker of sorts (maybe there's a most suitable name for it, but this is the best I could come up with). In front of the player there will be a path marker, which will determine how the player will move once he finishes planning his turn. The player may click and drag the marker to the position they choose, but the marker can only be moved within a defined working area (the gray bit). So I'm now stuck with two problems: First of all, how exactly should I define that workable area? I can imagine maybe two vectors that have the player as a starting point to form the workable angle, and maybe those two arcs could come from circles that have their center where the player is, but I definetly don't know how to put this all together. And secondly, after I've defined the area where the marker can be placed, how can I enforce that the marker should only stay within that area? For example, if the player clicks and drags the marker around, it may move freely within the working area, but must not leave the boundaries of the area. So for example, if the player starts dragging the marker upwards, it will move upwards until it hits he end of the working area (first diagram below), but if after that the player starts dragging sideways, the marker must follow the drag while still within the area (second diagram below). I hope this wasn't all too confusing. Thanks, guys.

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  • Beyond S&OP: Integrated Business Planning

    - by Paul Homchick
    In most corporations, planning is done at the department level — leaving disconnects and gaps across different departments. Finance sets revenue and profit goals with minimum validation from Manufacturing that the company has the resources, material, capacity, or demand to reach these goals. On the operations side, Manufacturing is developing plans to balance demand and supply but seldom knows if the resulting "plan" will meet the budgets on which the company's revenue and profit goals are based. The Sales department agrees to quotas that meet Finance's revenue goals without a complete understanding of what manufacturing can deliver. Integrated Business Planning (IBP) bridges these gaps in corporate planning systems. Integrated Business Planning integrates the financial planning provided by EPM systems with operations planning provided by Sales and Operations Planning solutions. This means that revenue goals and budgets are validated against a bottom-up operating plan, and that the operating plan is reconciled against financial goals. When detailed changes are made to the operations plan, planners can immediately see the big picture impact of the changes. IBP also addresses one the CFO's big concerns—the reliability of the revenue forecast. Operating plans are updated daily or weekly from a precise forecast based on current market conditions. These updated plans are then made available so that financial analysts are working with data that best represents what is going to happen - not what they projected would happen based on last quarter's data. For a discussion in more depth, see my article: Improve Reliability of Financial Forecasts with Integrated Business Planning in Supply & Demand Chain-Executive Magazine.

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  • Beyond S&OP: Integrated Business Planning

    - by Paul Homchick
    In most corporations, planning is done at the department level — leaving disconnects and gaps across different departments. Finance sets revenue and profit goals with minimum validation from Manufacturing that the company has the resources, material, capacity, or demand to reach these goals. On the operations side, Manufacturing is developing plans to balance demand and supply but seldom knows if the resulting "plan" will meet the budgets on which the company's revenue and profit goals are based. The Sales department agrees to quotas that meet Finance's revenue goals without a complete understanding of what manufacturing can deliver. Integrated Business Planning (IBP) bridges these gaps in corporate planning systems. Integrated Business Planning integrates the financial planning provided by EPM systems with operations planning provided by Sales and Operations Planning solutions. This means that revenue goals and budgets are validated against a bottom-up operating plan, and that the operating plan is reconciled against financial goals. When detailed changes are made to the operations plan, planners can immediately see the big picture impact of the changes. IBP also addresses one the CFO's big concerns—the reliability of the revenue forecast. Operating plans are updated daily or weekly from a precise forecast based on current market conditions. These updated plans are then made available so that financial analysts are working with data that best represents what is going to happen - not what they projected would happen based on last quarter's data. For a discussion in more depth, see my article: Improve Reliability of Financial Forecasts with Integrated Business Planning in Supply & Demand Chain-Executive Magazine.

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  • Migrating Forms to Java or ADF, the truth and no FUD

    - by Grant Ronald
    The question about migrating Forms to Java (or ADF or APEX) comes up time and time again.  I wanted to pull some core information together in a single blog post to address this question. The first question I always ask is "WHY" - Forms may still be a viable option for you so "if it ain't broke don't fix it".  Bottom line is whatever anyone tells you, its going to be a considerable effort and cost to migrate from Forms to something else so the business is going to want to know WHY you spend all those hard earned dollars switching from something that might have been serving you quite adequately. Second point, if you are going to switch, I would encourage you NOT to look at building a Forms clone.  So many times I see people trying to build an ADF application and EXACTLY mimic the Forms model - ADF is NOT a Forms clone.  You should be building to the sweet spot of your target technology, not your 20 year old client/server technology.  This is also the chance for the business to embrace change, so maybe look at new processes, channels and technology options that weren't available when you first developed your Forms applications. To help you understand what is involved, I've put together a number of resources. Thinking about migration of Forms to Java, ADF or APEX, read this to prepare yourself Oracle Forms to ADF: When, Why and How - this gives you an overview of our vision, directly from Oracle Product Management Redeveloping a Forms Application with Oracle JDeveloper and Oracle ADF.  This is a conference session from myself and Lynn Munsinger on how ADF can be used in a Forms migration/rewrite As someone who manages both Forms and ADF Product Management teams, I've a foot in either camp and am happy to see you use either tool.  However, I want you to be able to make an informed decision.  My hope is that there information sources will help you do that.

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  • Should Professional Development occur on company time?

    - by jshu
    As a first-time part-time software developer at a small consulting company, I'm struggling to organise time to further my own software development knowledge - whether that's reading a book, keeping up with the popular questions on StackOverflow, researching a technology we're using in-depth, or following the front page of Hacker News. I can see results borne from my self-allocated study time, but listing and demonstrating the skills and knowledge gained through Professional Development is difficult. The company does not have any defined PD policy, and there's a lot of pressure to get something deliverable done now! when working for consultants. I've checked what my coworkers do, and they don't appear to allocate any time to self-improvement; they just work at the problems they're given, looking up specific MSDN references, code samples, and the like as they need them. I realise that PD policy is going to vary across companies of different size and culture, and a company like my own is probably a bit of an edge case. I'd love to hear views and experiences from more seasoned developers; especially those who have to make the PD policy choices in their team or company. I'd also like to learn about the more radical approaches to PD, even if they're completely out there; it's always interesting to see what other people are trying. Not quite a summary, but what I'm trying to ask: Is it common or recommended for companies to allocate PD time? Whose responsibility is it to ensure a developer's knowledge and skills are up to date? Should a part-time work schedule inspire a lower ratio of PD time : work? How can a developer show non-developer coworkers that reading blogs and books is net productive? Is reading blogs and books actually net productive? (references welcomed) Is writing blogs effective as a way of PD? (a recent theme on Hacker News) This is sort of a broad question because I don't know exactly which questions I need to ask here, so any thoughts on relevant issues I haven't addressed are very welcome.

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  • RAM caching causes severe performance drops

    - by B T
    I have read plenty of threads on memory caching and the standard response of "large cache is good, it shouldn't effect performance", "the kernel knows best". I have recently upgraded from 12.04 to 12.10 and changed from VirtualBox to VMware Workstation and the performance differences are severe (I suspect it is because of the latter). When I am running my virtual machine the system load monitor graph shows less than 50% memory usage generally. System load indicator is showing me that the rest of my RAM is used in the cache all the time. Plain and simple this is the comparison: BEFORE Cache was very sparingly used, pretty much none of my memory usage was the cache Swappiness was 0 (caused my memory to be used first, then swap only if needed) Performance was quite good and logical RAM was used fully first, caching was minimal. I could run enough software to utilize my full 4GB of RAM without any performance degradation whatsoever Swap space was then used as needed which was obviously slower (I am on a HDD) but was still usable when the current program was loaded into memory AFTER Cache is used to fill the full 4GB as soon as my virtual machine is run Swappiness is 0 (same behaviour as before but cache uses full memory straight away) Performance is terrible and unusable while running Ubuntu software Basic things like changing windows takes 2 minutes + Changing screens happens frame by frame over sometimes up to 5 minutes Cannot run an IDE and VM like I could with ease before So basically, any suggestions on how to take my performance back to how it was before while keeping my current setup? My suspicion is VMWare is the problem, but how do I see what is tied to the use of the cache? Surely there is a way to control this behaviour in software as polished as VMware? Thanks EDIT: Could also be important to note that the behaviour differs depending on whether VMware is open or closed. If VMware is open, then the ram will lock at like 50% and 50% cache and go into the complete lock up mentioned above. Contrastingly, if VMware is closed (after being open), then the RAM will continue to rise as it needs / cache will stay as the complete remaining memory and there is no noticeable performance degradation.

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  • Help me select a "Simpler" target to create a new language: .NET, LLVM, Go, Own VM

    - by mamcx
    Lets define "Simple". This is my first language. I have no previous experience I will not dedicate +4 years to learn it properly. I'm a professional software [developer], but as an amateur in this area, I want instant gratification. If the idea shows a future, I could rewrite it. I don't want to do everything from scratch. In fact, if there exists a way to get GO (for example), change its syntax, add some sugar, give some extra functions and leave intact everything else, that would be perfect! From the example of coffescript/scala I think is better to build on top of some rich runtime like .NET/GO so I don't need to rewrite everything. HOWEVER, if is better other way, no problem for the first try! I want it in a week. I need it in a week so it will really take a month. Then it truly takes 3 months. But I don't want to put more that 3 months on this. I could reduce the scope of my language, but I hope the tools will help me a lot... I want to build a new language. Similar to python, but typed. I wonder what to build it on top of. I like the idea of building on top of GO. To get their sane (IMHO) OO paradigm (I plan to do the same, using interfaces, not inheritance), get goroutines and some other stuff. In my naive thinking I imagine that spit another language could help me to debug it more easily. However, look like everyone is building on top of something like .NET (don't like Java), LLVM or make it own VM. I read http://createyourproglang.com/ (great!) and the part of the VM look "easy" to me. So, what I need is the proper criteria and question I need to know in advance to have a fair shot at make this.

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  • Interpreting Others' Source Code

    - by Maxpm
    Note: I am aware of this question. This question is a bit more specific and in-depth, however, focusing on reading the actual code rather than debugging it or asking the author. As a student in an introductory-level computer science class, my friends occasionally ask me to help them with their assignments. Programming is something I'm very proud of, so I'm always happy to oblige. However, I usually have difficulty interpreting their source code. Sometimes this is due to a strange or inconsistent style, sometimes it's due to strange design requirements specified in the assignment, and sometimes it's just due to my stupidity. In any case, I end up looking like an idiot staring at the screen for several minutes saying "Uh..." I usually check for the common errors first - missing semicolons or parentheses, using commas instead of extractor operators, etc. The trouble comes when that fails. I often can't step through with a debugger because it's a syntax error, and I often can't ask the author because he/she him/herself doesn't understand the design decisions. How do you typically read the source code of others? Do you read through the code from top-down, or do you follow each function as it's called? How do you know when to say "It's time to refactor?"

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  • double screen in ubuntu 12.04?

    - by johan
    I am using ubuntu 12.04 and my video card is ATI Radeon 5000. I cannot use double screen (extended version). I get this error The selected configuration for displays could not be applied requested position/size for CRTC 148 is outside the allowed limit: position=(1280, 0), size=(1280, 768), maximum=(1440, 1440) I tried all display settings but it does not work. Some outputs from the system settings: root@ubuntu:~# lshw -C display *-display description: VGA compatible controller product: Madison [Radeon HD 5000M Series] vendor: Hynix Semiconductor (Hyundai Electronics) physical id: 0 bus info: pci@0000:01:00.0 version: 00 width: 64 bits clock: 33MHz capabilities: pm pciexpress msi vga_controller bus_master cap_list rom configuration: driver=fglrx_pci latency=0 resources: irq:46 memory:e0000000-efffffff memory:f0020000-f003ffff ioport:d000(size=256) memory:f0000000-f001ffff root@ubuntu:~# aticonfig --initial Uninitialised file found, configuring. Using /etc/X11/xorg.conf Saving back-up to /etc/X11/xorg.conf.original-0 root@ubuntu:~# cat /etc/X11/xorg.conf Section "ServerLayout" Identifier "aticonfig Layout" Screen 0 "aticonfig-Screen[0]-0" 0 0 EndSection Section "Module" Load "glx" EndSection Section "Monitor" Identifier "aticonfig-Monitor[0]-0" Option "VendorName" "ATI Proprietary Driver" Option "ModelName" "Generic Autodetecting Monitor" Option "DPMS" "true" EndSection Section "Device" Identifier "aticonfig-Device[0]-0" Driver "fglrx" BusID "PCI:1:0:0" EndSection Section "Screen" Identifier "Default Screen" DefaultDepth 24 EndSection Section "Screen" Identifier "aticonfig-Screen[0]-0" Device "aticonfig-Device[0]-0" Monitor "aticonfig-Monitor[0]-0" DefaultDepth 24 SubSection "Display" Viewport 0 0 Depth 24 EndSubSection EndSection I would appreciate any suggestions how to solve the problem. Thank you

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  • Junit test bluej [closed]

    - by user1721929
    Can someone make a junit test of this? public class PersonName { int NumberNames(String wholename) { // store the name passed in to the method String testname=wholename; // initialize number of names found int numnames=0; // on each iteration remove one name while(testname.length()>numnames) { // take the "white space" from the beginning and end testname = testname.trim(); // determine the position of the first blank // .. end of the first word int posBlank= testname.indexOf(' '); // cut off word /** * it continues to the stop sign because that is where you commanded it to end */ testname=testname.substring(posBlank+1,testname.length()); // System.out.println(numnames); // System.out.println(testname); numnames++; System.out.println(testname); } return numnames; } public static void main(String args[]) { PersonName One= new PersonName(); System.out.println(One.NumberNames("Bobby")); System.out.println(One.NumberNames("Bobby Smith")); System.out.println(One.NumberNames("Bobby L. Smith")); System.out.println(One.NumberNames(" Bobby Paul Smith Jr. ")); } }

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  • Integration error in high velocity

    - by Elektito
    I've implemented a simple simulation of two planets (simple 2D disks really) in which the only force is gravity and there is also collision detection/response (collisions are completely elastic). I can launch one planet into orbit of the other just fine. The collision detection code though does not work so well. I noticed that when one planet hits the other in a free fall it speeds backward and goes much higher than its original position. Some poking around convinced me that the simplistic Euler integration is causing the error. Consider this case. One object has a mass of 1kg and the other has a mass equal to earth. Say the object is 10 meters above ground. Assume that our dt (delta t) is 1 second. The object goes to the height of 9 meters at the end of the first iteration, 7 at the end of the second, 4 at the end of the third and 0 at the end of the fourth iteration. At this points it hits the ground and bounces back with the speed of 10 meters per second. The problem is with dt=1, on the first iteration it bounces back to a height of 10. It takes several more steps to make the object change its course. So my question is, what integration method can I use which fixes this problem. Should I split dt to smaller pieces when velocity is high? Or should I use another method altogether? What method do you suggest? EDIT: You can see the source code here at github:https://github.com/elektito/diskworld/

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  • Positioning a sprite in XNA: Use ClientBounds or BackBuffer?

    - by Martin Andersson
    I'm reading a book called "Learning XNA 4.0" written by Aaron Reed. Throughout most of the chapters, whenever he calculates the position of a sprite to use in his call to SpriteBatch.Draw, he uses Window.ClientBounds.Width and Window.ClientBounds.Height. But then all of a sudden, on page 108, he uses PresentationParameters.BackBufferWidth and PresentationParameters.BackBufferHeight instead. I think I understand what the Back Buffer and the Client Bounds are and the difference between those two (or perhaps not?). But I'm mighty confused about when I should use one or the other when it comes to positioning sprites. The author uses for the most part Client Bounds both for checking whenever a moving sprite is of the screen and to find a spawn point for new sprites. However, he seems to make two exceptions from this pattern in his book. The first time is when he wants some animated sprites to "move in" and cross the screen from one side to another (page 108 as mentioned). The second and last time is when he positions a texture to work as a button in the lower right corner of a Windows Phone 7 screen (page 379). Anyone got an idea? I shall provide some context if it is of any help. Here's how he usually calls SpriteBatch.Draw (code example from where he positions a sprite in the middle of the screen [page 35]): spriteBatch.Draw(texture, new Vector2( (Window.ClientBounds.Width / 2) - (texture.Width / 2), (Window.ClientBounds.Height / 2) - (texture.Height / 2)), null, Color.White, 0, Vector2.Zero, 1, SpriteEffects.None, 0); And here is the first case of four possible in a switch statement that will set the position of soon to be spawned moving sprites, this position will later be used in the SpriteBatch.Draw call (page 108): // Randomly choose which side of the screen to place enemy, // then randomly create a position along that side of the screen // and randomly choose a speed for the enemy switch (((Game1)Game).rnd.Next(4)) { case 0: // LEFT to RIGHT position = new Vector2( -frameSize.X, ((Game1)Game).rnd.Next(0, Game.GraphicsDevice.PresentationParameters.BackBufferHeight - frameSize.Y)); speed = new Vector2(((Game1)Game).rnd.Next( enemyMinSpeed, enemyMaxSpeed), 0); break;

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  • Why We Need UX Designers

    - by Tim Murphy
    Ok, so maybe this is really why I need UX designers.  While I have always had an interest in photography and can appreciate a well designed user interface putting one together is an entirely different endeavor.  Being color blind doesn’t help, but coming up with ideas is probably the biggest portion of the issue.  I can spot things that just don’t look like they work right, but what will? UX designers is an area that most companies do not spend much if any resources.  As they say, you only get one chance to make a first impression and and a poorly designed site or application is a bad first impression.  Given that they you would think that companies would invest more in appearance and usability. One of two things need to be done to rectify this issue.  Either we need to start educating our developers on user experience and design or we need to start finding ways to subsidize putting full time designers on our project teams.  Maybe it should be a time share type of situation, but something needs to be done.  As architects we need to impress on our project stakeholders the importance of User Experience and why it should be part of the budget.  If they hear it often enough eventually they may present it to you as their own idea. del.icio.us Tags: User Experience,UX,Application Design

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  • ORA-600 Troubleshooting

    - by [email protected]
    Have you observed an ORA-0600 or ORA-07445 reported in your alert log? The ORA-600 error is the generic internal error number for Oracle program exceptions. It indicates that a process has encountered a low-level, unexpected condition. The ORA-600 error statement includes a list of arguments in square brackets: ORA 600 "internal error code, arguments: [%s], [%s],[%s], [%s], [%s]" The first argument is the internal message number or character string. This argument and the database version number are critical in identifying the root cause and the potential impact to your system.  The remaining arguments in the ORA-600 error text are used to supply further information (e.g. values of internal variables etc).   Looking for the best way to diagnose? There is an ORA-600 Troubleshooter Tool available in My Oracle Support.  This tool will lead you to applicable content in My Oracle Support on the problem and can be used to investigate the problem with argument data from the error message or you can pull out the first 10 or 15 stack pointers from the associated trace file to match up against known bugs. Note 153788.1 ORA-600/ORA-7445 TroubleshooterNote 1082674.1 A Video To Demonstrate The Usage Of The ORA-600/ORA-7445 Lookup Tool [Video] Also, take a quick look at the Master Note for Diagnosing ORA-600 ( MasterNoteORA600.docx) for some tips on diagnosing.

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  • Unable to boot Windows after installing Ubuntu 12.04 - error: invalid efi file path

    - by user113350
    I have a Laptop (ASUS X310A, I installed Ubuntu 12.04 to be side by side with Windows 7 but I seem to have gotten a problem with booting Windows 7. I used the Boot Repair twice with no results. Boot-Repair info: http://paste.ubuntu.com/1417623/ The error I get when starting Windows 7 from GRUB is: error: invalid efi file path In Boot Manager or Menu, I have 3 options now: 2x for Ubuntu (maybe cause I did boot-repair twice) 1x Windows boot manager (If I boot this it opens "ASUS Preload Wizard", it gives me the option to re-install windows losing all previous data -) When I was making the partition before installing Ubuntu, I made the new partition by making sda4 smaller and adding ext4 mounted: "\" and adding a swap area. Installed it and it didn't work, nothing worked. So i booted Ubuntu from the USB again and deleted the partitions I made and decided to make sda3 smaller and making the partitions but this time it gave me the option that I could mount sda3 on "\windows" or "\dos" I ignored it and didn't choose neither because the I know that it doesn't need to be mounted and proceeded to create what is now sda7 (ext4) and sda8 (swap area). It still didn't work so I booted from USB and did the first boot-repair, so I was able to boot Ubuntu now but not windows, but when I did it through my USB I was not able to update boot-repair, so i decided to redo the boot-repair from Ubuntu running on the Hardisk (fully updated) and it still didn't work. In GRUB this is what i see (when booting using Ubuntu as first option in Boot Menu): Ubuntu, with Linux 3.2.0-29-generic Ubuntu, with Linux 3.2.0-29-generic (recovery mode) Windows UEFI loader Windows Boot UEFI bootx64.efi.bkp Windows 7 (loader) (on /dev/sda3) Windows Recovery Environment (loader) (on /dev/sda5) I tried all the ones starting with "Windows" they all don't work Please help, Many Thanks

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  • MVC Validation with ModelState.isValid through a wizard

    - by Emmanuel TOPE
    I'm working on a small educational project on MVC 3, and I'm facing a small problem, when attempting to handle validation in my application through a wizard. I tried to get benefit from the ability of MVC3 to deliver content of a different view using the same URL, when handling an [HttpPost] method on a page. I my case,my main model's class contains about ten [Required] properties, that I would like to expose through a small wizard in 3 steps , So I want that the user may be able to enter his personal informations in the first step, then respond to some questions in the second stepp and finally receive a confirmation mail from the web application whit his credentials in the last step. I can't access the last step, because of the ModelState.isValid method that I use to handle validations, and which can't perform properly if I define some properties as [Required], but don't put them on the first view. As the replies to those questions remain in a couple of choices, I've thinked that I may use some nullable bool? for in order to avoid validation issues, but know that it's not the proper way. Are there someone who would like to help me find a way to extend my validation to those three steps ? Thanks in advance and sorry for my english, I'm not a native speaker.

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  • Why do I need to create a bios-grub partition when I install 12.04?

    - by raj
    Is the bios-grub partition in Ubuntu 12.04 mandatory? I have used 11.04, 11.10 and 12.04, But I was never asked for this. Today I tried a fresh installation of Ubuntu 12.04 and for the first time I was asked for this Grub partition of minimum 1Mb. I first tried to reinstall 12.04, but the error continued. So I installed Fedora 16, Keeping all partitions as they were (replaced Ubuntu with Fedora), And then did another fresh installation of 12.04. Is it ok to continue with this grub partition or is there a fault in my system's hardware? If this is a (hardware) fault, how can I fix it? I'm using a Lenovo S10-2 Ideapad. The only OS right now installed is Ubuntu 12.04. well, let me answer. It was /usr/bin/xorg issue that I had with firstly installed precise. I used fedora16 basically for removing precise totally (my experience tells me ubuntu can't completely erase and reinstall by itself). this 1mb grub is created by fedora. I then wanted to remove it while reinstalling ubuntu but got caution bootloader may fail. hence I have to keep this 1mb drive. but prior to yesterday, i used both fedora and ubuntu, even same CDs, but had no such partition. my question is if this partition is necessary or not? if not, how can i safely remove it from my system? Am using only ubuntu 12.04 -- before and after (now).

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  • How to indicate reliability when reporting availability of competencies

    - by Jan Doggen
    We have employees with competencies: Pete Welder Carpenter Melissa Carpenter Assume they both work 40 hours/week, and have not yet been assigned work. We need to report the availability of these competencies, expressed in hours. As far as I can see now, we can report this in two ways: Method A. When someone has multiple competencies, count them both. Welder 40 hours Carpenter 80 hours Method B. When someone has multiple competencies, count an equal division of hours for each Welder 20 hours Carpenter 60 hours Method A has our preference: - A good planner will know to plan the least available competency first. If 30 hours of welding is planned, we will be left with 10 welder, 50 carpenter. - Method B has the disadvantage that the planner thinks he cannot plan the job when 30 hours of welding is required. However, if we report this we would like to give an estimate of the reliability of the numbers for each competency, i.e. how much are these over-reported? In my example A, would I say that carpenter is 100% over-reported, or 50%, or maybe another number? How would I calculate this for large numbers of competencies? I'm sure we are not the first ones dealing with this, is there a 'usual' way of doing this in planning? Additionally: - Would there be an even better method than A or B? - Optionally, we also have an preference order of competencies (like: use him/her in this order), Pete could be 1. welder 2. carpenter. Does this introduce new options?

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