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  • Being a more attractive job candidate - Certs XOR Degree

    - by Zephyr Pellerin
    I'm currently working in an IT position, where I do helpdesk stuff, and predominantly security related issues/consulting (In the loosest sense of the term) In-House and for Service-Contract clients (as the only/acting CCSP [I guess I should say only person with Cisco experience] in my organization). I've professionally written Kernel Mode drivers for a gaming company. Among other things that I'm proud to put on a resume. I think of myself as very reasonably qualified as a System Administrator, With excellent Cisco experience, among other things I think would make a good addition to almost any IT staff in need of a new employee. However, Something has always tripped me up - Human Resources. Let me explain, I decided to skip the university route - I'm immensely glad that I did, The computer science graduates that I've met and work with rarely know much of anything about Computers (Until they gain some 'real' experience), Even when asked about Theoretical Computing fundamentals they can rattle something off about Turing Completeness but rarely do they understand the mathematical underpinnings. In short, I think instead of going to college, I'd rather pick up some real world experience. However, Apparently, Employers rarely think the same way. A quick perusal of jobs through the standard job search engine yields nothing short of a conspiracy to exclude anyone without 'A Bachelors Degree in Computer Science or Equivalent'. Interviews I've had in the past have almost always been entangled with - 1. My Age (Which I can't really change) and 2. Lack of Degree. Employers frequently disregard the CCNA/CCSP, The experience I've gained through internships, My extensive experience in x86 assembly and C, among so many other things I like to think are valuable to employers - In lieu of the fact that I don't have a piece of paper. So, AS AN EMPLOYER - Is it even worth working on my CCIE? Or should I pad my resume with certifications that are easier to acquire (Like CISSP, MSCE, Network+, etc.). Or should I ditch the whole idea and head back to get a Mathematics or CS degree?

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  • Challenge 19 – An Explanation of a Query

    - by Dave Ballantyne
    I have received a number of requests for an explanation of my winning query of TSQL Challenge 19. This involved traversing a hierarchy of employees and rolling a count of orders from subordinates up to superiors. The first concept I shall address is the hierarchyId , which is constructed within the CTE called cteTree.   cteTree is a recursive cte that will expand the parent-child hierarchy of the personnel in the table @emp.  One useful feature with a recursive cte is that data can be ‘passed’ from the parent to the child data.  The hierarchyId column is similar to the hierarchyId data type that was introduced in SQL Server 2008 and represents the position of the person within the organisation. Let us start with a simplistic example Albert manages Bob and Eddie.  Bob manages Carl and Dave. The hierarchyId will represent each person’s position in this relationship in a single field.  In this simple example we could append the userID together into a varchar field as detailed below. This will enable us to select a branch of the tree by filtering using Where hierarchyId  ‘1,2%’ to select Bob and all his subordinates.  Naturally, this is not comprehensive enough to provide a full solution, but as opposed to concatenating the Id’s together into a varchar datatyped column, we can apply the same theory to a varbinary.  By CASTing the ID’s into a datatype of varbinary(4) ,4 is used as 4 bytes of data are used to store an integer and building a hierarchyId  from those.  For example: The important point to bear in mind for later in the query is that the binary data generated is 'byte order comparable'. ie We can ORDER a dataset with it and the resulting data, will be in the order required. Now, would probably be a good time to download the example file and, after the cte ‘cteTree’, uncomment the line ‘select * from cteTree’.  Mark this and all prior code and execute.  This will show you how this theory directly relates to the actual challenge data.  The only deviation from the above, is that instead of using the ID of an employee, I have used the row_number() ranking function to order each level by LastName,Firstname.  This enables me to order by the HierarchyId in the final result set so that the result set is in the required order. Your output should be something like the below.  Notice also the ‘Level’ Column that contains the depth that the employee is within the tree.  I would encourage you to ‘play’ with the query, change the order in the row_number() or the length of the cast in the hierarchyId to see how that effects the outcome.  The next cte, ‘cteTreeWithOrderCount’, is a join between cteTree and the @ord table, and COUNT’s the number of orders per employee.  A LEFT JOIN is employed here to account for the occasion where an employee has made no sales.   Executing a ‘Select * from cteTreeWithOrderCount’ will return the result set as below.  The order here is unimportant as this is only a staging point of the data and only the final result set in a cte chain needs an Order by clause, unless TOP is utilised. cteExplode joins the above result set to the tally table (Nums) for Level Occurances.  So, if level is 2 then 2 rows are required.  This is done to expand the dataset, to create a new column (PathInc), which is the (n+1) integers contained within the heirarchyid.  For example, with the data for Robert King as given above, the below 3 rows will be returned. From this you can see that the pathinc column now contains the values for Andrew Fuller and Steven Buchanan who are Robert King’s superiors within the tree.    Finally cteSumUp, sums the orders for each person and their subordinates using the PathInc generated above, and the final select does the final simple mathematics and filters to restrict the result set to only the ‘original’ row per employee.

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  • Java Spotlight Episode 76: Pro Java FX2 - A Definative Guide to Rich Clients with Java Technology

    - by Roger Brinkley
    Tweet An interview with the authors of Pro Java FX2: A Definative Guide to Rich Clients with Java Technology. Right-click or Control-click to download this MP3 file. You can also subscribe to the Java Spotlight Podcast Feed to get the latest podcast automatically. If you use iTunes you can open iTunes and subscribe with this link:  Java Spotlight Podcast in iTunes. Show Notes News Angela Caicedo has created 3 new Java FX screen cast videos on java UTube channel: Part 1: Building your First Java FX Application with Netbeans 7.1, Part 2: Building your First Java FX Application with Netbeans 7.1, and Getting Started with Scene Builder.  Events March 26-29, EclipseCon, Reston, USA March 27, Virtual Developer Days - Java (Asia Pacific (English)),9:30 am to 2:00pm IST / 12:00pm to 4.30pm SGT  / 3.00pm - 7.30pm AEDT April 4-5, JavaOne Japan, Tokyo, Japan April 12, GreenJUG, Greenville, SC April 17-18, JavaOne Russia, Moscow Russia April 18–20, Devoxx France, Paris, France April 26, Mix-IT, Lyon, France, May 3-4, JavaOne India, Hyderabad, India Feature InterviewPro JavaFX 2: A Definitive Guide to Rich Clients with Java Technology is available from Amazon.com in either paperback or on the Kindle.James L. (Jim) Weaver is a Java and JavaFX developer, author, and speaker with a passion for helping rich-client Java and JavaFX become preferred technologies for new application development. Books that Jim has authored include Inside Java, Beginning J2EE, and Pro JavaFX Platform, with the latter being updated to cover JavaFX 2.0. His professional background includes 15 years as a systems architect at EDS, and the same number of years as an independent developer. Jim is an international speaker at software technology conferences, including the JavaOne conferences in San Francisco and São Paulo. Jim blogs at http://javafxpert.com, tweets @javafxpert. Weiqi Gao is a principal software engineer with Object Computing, Inc., in St. Louis, MO. He has more than 18 years of software development experience and has been using Java technology since 1998. He is interested in programming languages, object-oriented systems, distributed computing, and graphical user interfaces. He is a presenter and a member of the steering committee of the St. Louis Java Users Group. Weiqi holds a PhD in mathematics. Stephen Chin is chief agile methodologist at GXS and a technical expert in client UI technologies. He is lead author on the Pro Android Flash title and coauthored the Pro JavaFX Platform title, which is the leading technical reference for JavaFX. In addition, Stephen runs the very successful Silicon Valley JavaFX User Group, which has hundreds of members and tens of thousands of online viewers. Finally, he is a Java Champion, chair of the OSCON Java conference, and an internationally recognized speaker featured at Devoxx, Codemash, AnDevCon, Jazoon, and JavaOne, where he received a Rock Star Award. Stephen can be followed on twitter @steveonjava and reached via his blog: http://steveonjava.com.Dean Iverson has been writing software professionally for more than 15 years. He is employed by the Virginia Tech Transportation Institute, where he is a rich client application developer. He also has a small software consultancy called Pleasing Software Solutions, which he cofounded with his wife. Johan Vos started to work with Java in 1995. As part of the Blackdown team, he helped port Java to Linux. With LodgON, the company he cofounded, he has been mainly working on Java-based solutions for social networking software. Because he can't make a choice between embedded development and enterprise development, his main focus is on end-to-end Java, combining the strengths of backend systems and embedded devices. His favorite technologies are currently Java EE/Glassfish at the backend and JavaFX at the frontend. Johan's blog can be followed at http://blogs.lodgon.com/johan, he tweets at http://twitter.com/johanvos. Mail Bag What’s Cool Gerrit Grunwald's SteelSeries FX Experience Tools Canned Animations ComboBox

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  • Migrating VB6 to HTML5 is not a fiction - Customer success story

    - by Webgui
    All of you VB developers in the present or past would probably find it hard to believe that the old VB code can be migrated and modernized into the latest .NET based HTML5 without having to rewrite the application. But we have been working on such tools for the past couple of years and already have several real world applications that were fully 'transposed' from VB6. The solution is called Instant CloudMove and its main tool is called the TranspositionStudio. It is a unique solution that relies on the concept of transposition. Transposition comes from mathematics and music and refers to exchanging elements while everything else remains the same or moving an element as is from one environment to another. This means that we are taking the source code and put it in a modern technological environment with relatively few adjustments.The concept is based on a set of Mapping Expressions which are basically links between an element in the source environment and one in the target environment that has the same functionality. About 95% of the code is usually mapped out-of-the-box and the rest is handled with easy-to-use mapping tools designed for Visual Studio developers providing them with a familiar environment and concepts for completing the mapping and allowing them to extend and customize existing mapping expressions. The solution is also based on a circular workflow that enables developers to make any changes as required until the result is satisfying.As opposed to existing migration solutions that offer automation are usually a “black box” to the user, the transposition concept enables full visibility, flexibility and control over the code and process at all times allowing to also add/change functionalities or upgrade the UI within the process and tools.This is exactly the case with our customer’s aging VB6 PMS (Property Management System) which needed a technological update as well as a design refresh. The decision was to move the VB6 application which had about 1 million lines of code into the latest web technology. Since the application was initially written 13 years ago and had many upgrades since the code must be very patchy and includes unused sections. As a result, the company Mihshuv Group considered rewriting the entire application in Java since it already had the knowledge. Rewrite would allow starting with a clean slate and designing functionality, database architecture, UI without any constraints. On the other hand, rewrite entitles a long and detailed specification work as well as a thorough QA and this translates into a long project with high risk and costs.So the company looked for a migration solution as an alternative; the research lead to Gizmox and after examining the technology it was decided to perform a hybrid project which would include an automatic transposition of the core of the VB6 application (200,000 lines of code) while they redesigning the UI, adding new functionality, deleting unused code and rewriting about 140 reports with Crystal Reports will be done manually using Visual WebGui development tools.The migration part of the project was completed in 65 days by 3 developers from Mihshuv Group guided by Gizmox migration experts while the rewrite and UI upgrade tasks took about the same. So in only a few months period Mihshuv Group generated an up-to-date product, written in the latest Web technology with modern, friendly UI and improved functionality. Guest selection screen of the original VB6 PMS Guest selection screen on the new web–based PMS Compared to the initial plan to rewrite the entire application in Java, the hybrid migration/rewrite approach taken by Mihshuv Group using Gizmox technology proved as a great decision. In terms of time and cost there were substantial savings; from a project that was priced for at least a year (without taking into account the huge risk and uncertainty) it became a few months project only. More about this and other customer stories can be found here

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  • Solving Diophantine Equations Using Python

    - by HARSHITH
    In mathematics, a Diophantine equation (named for Diophantus of Alexandria, a third century Greek mathematician) is a polynomial equation where the variables can only take on integer values. Although you may not realize it, you have seen Diophantine equations before: one of the most famous Diophantine equations is: We are not certain that McDonald's knows about Diophantine equations (actually we doubt that they do), but they use them! McDonald's sells Chicken McNuggets in packages of 6, 9 or 20 McNuggets. Thus, it is possible, for example, to buy exactly 15 McNuggets (with one package of 6 and a second package of 9), but it is not possible to buy exactly 16 nuggets, since no non- negative integer combination of 6's, 9's and 20's adds up to 16. To determine if it is possible to buy exactly n McNuggets, one has to solve a Diophantine equation: find non-negative integer values of a, b, and c, such that 6a + 9b + 20c = n. Write an iterative program that finds the largest number of McNuggets that cannot be bought in exact quantity. Your program should print the answer in the following format (where the correct number is provided in place of n): "Largest number of McNuggets that cannot be bought in exact quantity: n"

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  • Computer science textbooks

    - by Barrett Conrad
    I would like to try the book question a little bit differently. My goal is to know what the community thinks are the quintessential computer science textbooks. <beginsadstory>I lost all of my computer science and math books from college in Hurricane Katrina in 2005. I greatly miss having my familiar tomes to refer to when topics and problems come up, so I am looking to rebuild my library.<endsadstory> What are your recommendations for the best examples of academic caliber books for the field of computer science and its associated mathematics? I am looking for books on subjects like computational theory, programming languages, compilers, operating systems, algorithms and so on. Don't limit your suggestions to your textbooks only. If there is a book you have read that covers computer science or a related math in a formal way, but is not strictly a textbook, I would be love to hear about them as well. Finally, for the sake of creating a good reference for all of us, may I suggest posting one book per answer so they can be rated individually.

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  • How to get local bzr commits to server?

    - by C.W.Holeman II
    lanchpad.net states that for project Emle - Electronic Mathematics Laboratory Equipment 2.0 series is the current focus of development This is what I have done so far: Set the launchpad.net project to import from the sourceforge.net project Emle (this actually set the launchpad.net project to mirror the sourceforge.net project rather than just inport the content once) Examined the launchpad.net project to see that the three commits (#1 - #3) which were done in the sourceorge.net project previousley made it into launchpad.net. Used bzrto get the launchpad.net project which I did while is was still set for mirroring. Made three changes and commits using bzr (#4 - #6). Was unable to see the changes on the launchpad.net site. Requested the mirroring to be stopped (it did). Here is an extract from lanchpad.net for project Emle 2.0 series showing that launchpad.net has #1 - #3: Code for this series The following branch has been registered as the mainline branch for this release series: lp:emle - C.W.Holeman II 3 revisions, 3 in the past month. Here on my system showing changes #1 - #6: $ bzr log --line 6: C.W.Holeman II 2010-02-27 #528096 Corrected setting of paramter value for emleDi... 5: C.W.Holeman II 2010-02-27 Minor refactor - improved comment regarding workaround... 4: C.W.Holeman II 2010-02-27 #529089 #529087 Index file html tag lang attribute cor... 3: cwhii 2010-02-25 {Emle 2.4-5 (BL0011)} New top levels: trunk and tags. 2: cwhii 2010-02-25 New top levels: trunk and tags. 1: cwhii 2010-02-25 New top level trunk and tags. How do I get the changes that are in bzr on my system to apply to launchpad.net?

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  • Getting started with character and text processing (encoding, regular expressions)

    - by TK
    I'd like to learn foundations of encodings, characters and text. Understanding these is important for dealing with a large set of text whether that are log files or text source for building algorithms for collective intelligence. My current knowledge is pretty basic: something like "As long as I use UTF-8, I'm okay." I don't say I need to learn about advanced topics right away. But I need to know: Bit and bytes level knowledge of encodings. Characters and alphabets not used in English. Multi-byte encodings. (I understand some Chinese and Japanese. And parsing them is important.) Regular expressions. Algorithm for text processing. Parsing natural languages. I also need an understanding of mathematics and corpus linguistics. The current and future web (semantic, intelligent, real-time web) needs processing, parsing and analyzing large text. I'm looking for some resources (maybe books?) that get me started with some of the bullets. (I find many helpful discussion on regular expressions here on Stack Overflow. So, you don't need to suggest resources on that topic.)

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  • Getting a job in the games industry as a developer, just knowing a game engine

    - by numerical25
    I recently enrolled in a community college for games developement. But I am skeptical about the curriculum. I have no experience in the gaming industry so I wouldn't be able to tell whether it's a good investment or not. So I am asking you. I don't want to get too much into the details of all the classes I am taking so I will try to be brief. By the time I graduate, I should have a understanding of how a game engine works. I will be working with the Unreal Engine to develop a Multiplayer game from scratch. So in the process of my final project, I will learn how to work within the Unreal Engine, learn Python and learn how to use its API to connect to a remote server and build game mechanics. Overall I will also recieve an associates degree in game development. I learn C++ but not C. The director said he was trying to implement C in the program as well. What I notice is I will not learn how to build a 3D game engine from scratch. They do not teach any artificial intelligence (AI). I will not learn how to work with the graphics card using a graphics API such as DirectX or OpenGL. I know building a game engine from scratch is a little complex, but at the same time the track is requiring me to take some advanced mathematics courses such as calculus and geometry 1 and 2. I also got to take a physics class. I just think that's a little much for just learning how to use the Unreal Engine but not actually build one or try to learn the anatomy of a games engine. Is this good enough to possibly land my a job in the industry? If I left anything out or was not detail, please feel free to ask more questions. Edit: I do learn data structures and algorithms.

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  • Project Euler considered harmful

    - by xxxxxxx
    Hi, I've done some Project Euler problems and I was able to solve them very fast because I already knew all the theory behind them. I learned that "accidentaly" because I also had to learn it for university. I used to also solve olympiad problems, I wasn't very good but I was solving some of the problems. I've reached the conclusion that Project Euler problems are taken out of their context(and olympiad problems as well). That's why they are hard. Mathematics and it's theory is taught in order to make the problems easy. However, Project Euler apparently makes an invitation at making them hard again. Why ? I honestly think this is a complete waste of time. Mathematicians had centuries at their disposal in order to solve math problems and they developed theories to explain properly why certain things happen. I think olympiad problems and Project Euler problems are really useless. What's your take on Project Euler ? Do you get something out of it or do you just find formulas on some websites and implement the code fast and then get the result and solve the problem ?

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  • Formula parsing / evaluation routine or library with generic DLookup functionality

    - by tbone
    I am writing a .Net application where I must support user-defined formulas that can perform basic mathematics, as well as accessing data from any arbitrary table in the database. I have the math part working, using JScript Eval(). What I haven't decided on is what a nice way is to do the generic table lookups. For example, I may have a formula something like: Column: BonusAmount Formula: {CurrentSalary} * 1.5 * {[SystemSettings][Value][SettingName=CorpBonus AND Year={Year}]} So, in this example I would replace {xxx} and {Year} with the value of Column xxx from the current table, and I would replace the second part with the value of (select Value from SystemSettings WHERE SettingName='CorpBonus' AND Year=2008) So, basically, I am looking for something very much like the MS Access DLookup function: DLookup ( expression, domain, [criteria] ) DLookup("[UnitPrice]", "Order Details", "OrderID = 10248") But, I also need to overall parsing routine that can tell whether to just look up in the current row, or to look into another table. Would also be nice to support aggregate functions (ie: DAvg, DMax, etc), as well as all the weird edge cases handled. So I wonder if anyone knows of any sort of an existing library, or has a nice routine that can handle this formula parsing and database lookup / aggregate function resolution requirements.

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  • looking for a license key algorithm.

    - by giulio
    There are a lot of questions relating to license keys asked on stackoverflow. But they don't answer this question. Can anyone provide a simple license key algorithm that is technology independent and doesn't required a diploma in mathematics to understand ? The license key algorithm is similar to public key encryption. I just need something simple that can be implemented in any platform .Net/Java and uses simple data like characters. Preferably no byte translations required. So if a person presents a string, a complementary string can be generated that is the authorisation code. Below is a common scenario that it would be used for. Customer downloads s/w which generates a unique key upon initial startup/installation. S/w runs during trial period. At end of trial period an authorisation key is required. Customer goes to designated web-site, enters their code and get authorisation code to enable s/w, after paying :) Don't be afraid to describe your answer as though you're talking to a 5 yr old as I am not a mathemtician. Just need a decent basic algorithm, we're not launching nukes... NB: Please no philosophy on encryption nor who is Diffie-Hellman. I just need a basic solution.

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  • looking for a license key algorithm.

    - by giulio
    There are alot of questions relating to license keys asked on stackoverflow. But they don't answer this question. Can anyone provide a simple license key algorithm that is technology independent and doesn't required a diploma in mathematics to understand ? The license key algorithm is similar to public key encryption. I just need something simple that can be implemented in any platform .Net/Java and uses simple data like characters. Written as Pseudo code is perfect. So if a person presents a string, a complementary string can be generated that is the authorisation code. Below is a common scenario that it would be used for. Customer downloads s/w which generates a unique key upon initial startup/installation. S/w runs during trial period. At end of trial period an authorisation key is required. Customer goes to designated web-site, enters their code and get authorisation code to enable s/w, after paying :) Don't be afraid to describe your answer as though you're talking to a 5 yr old as I am not a mathemtician.

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  • LaTex: why partially showing up references?

    - by HH
    The bib.style part may be the problem. If I do not reference to references, do they show up? I have listed all errors below, the file compiles so I don't know whether they are related to partially-showing-up-references. For example, work with many authors gets only one author listed. I want to see references fully, not partially. Headers $ grep bib header.tex \usepackage{natbib} \bibliographystyle{abbrvnat} Errors $ grep -n -A 7 -B 7 Error *.log combined.log-505-! Illegal unit of measure (pt inserted). combined.log-506-<to be read again> combined.log-507- \futurelet combined.log-508-l.353 \hline combined.log-509- combined.log-510-? combined.log-511- combined.log:512:! Package caption Error: cite undefined. combined.log-513- combined.log-514-See the caption package documentation for explanation. combined.log-515-Type H <return> for immediate help. combined.log-516- ... combined.log-517- combined.log-518-l.374 ...n={CPU O(mlog(n))}, cite={topcoder:node}] combined.log-519- -- combined.log-559- [] combined.log-560- combined.log-561-) [10] combined.log-562-\openout2 = `references.aux'. combined.log-563- combined.log-564- (./references.tex combined.log-565- combined.log:566:! LaTeX Error: \include cannot be nested. combined.log-567- combined.log-568-See the LaTeX manual or LaTeX Companion for explanation. combined.log-569-Type H <return> for immediate help. combined.log-570- ... combined.log-571- combined.log-572-l.1 \include{timeUse.tex} Bibs.bib @misc{ Gundersen, author = "G. Gundersen", title = "Data Structures in Java for Matrix Computations", year = "2002" } @book{ Lennart, author = "R. Lennart", title = "Mathematics Handbook for Science and Engineering BETA", year = "2004" }

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  • Simple in-place discrete fourier transform ( DFT )

    - by Adam
    I'm writing a very simple in-place DFT. I am using the formula shown here: http://en.wikipedia.org/wiki/Discrete_Fourier_transform#Definition along with Euler's formula to avoid having to use a complex number class just for this. So far I have this: private void fft(double[] data) { double[] real = new double[256]; double[] imag = new double[256]; double pi_div_128 = -1 * Math.PI / 128; for (int k = 0; k < 256; k++) { for (int n = 0; n < 256; n++) { real[k] += data[k] * Math.Cos(pi_div_128 * k * n); imag[k] += data[k] * Math.Sin(pi_div_128 * k * n); } data[k] = Math.Sqrt(real[k] * real[k] + imag[k] * imag[k]); } } But the Math.Cos and Math.Sin terms eventually go both positive and negative, so as I'm adding those terms multiplied with data[k], they cancel out and I just get some obscenely small value. I see how it is happening, but I can't make sense of how my code is perhaps mis-representing the mathematics. Any help is appreciated. FYI, I do have to write my own, I realize I can get off-the shelf FFT's.

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  • Any book on designing and implementing a CRPG engine?

    - by Fabzter
    Hi! First, let me tell you, I am not really interested in making my own rpg engine (at least not in the near future, hehe), but I do feel like I want to understand the internals of how a rpg engine works. Why? Well, because I like to read about programming and design, It keeps me motivated and excited, and because I know I will learn a lot, for, even when I have been programming for some years now, I never stop considering myself an ignorant... there are simply SO many things involving a game engine (specially rpg ones, like branching storylines, and items and economics!) I'm eager to know. I've been searching (and thus, finding) lots of info online, but it is never focused in what I'm interested (most of it talks about the mathematics and AI algorithms implementation, which I know quite well), which is the design of overall structure, patterns, scripting engine, decision engine... damn, so many things I can't even imagine, since I've never done any game programming. I hope you know have an idea of how I feel, and how I want to learn for the sake of learning, and why would I want you to tell me if you know if there exist books touching the topics that interest me the most.

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  • How do I best remove the unicode characters that XHTML regards as non-valid using php?

    - by Andrew Stacey
    I run a forum designed to support an international mathematics group. I've recently switched it to unicode for better support of international characters. In debugging this conversion, I've discovered that not all unicode characters are considered as valid XHTML (the relevant website appears to be http://www.w3.org/TR/unicode-xml/). One of the steps that the forum software goes through before presenting the posts to the browser is an XHTML validation/sanitisation step. It seems a reasonable idea that at that stage it should remove any unicode characters that XHTML doesn't like. So my question is: Is there a standard (or best) way of doing this in PHP? (The forum is written in PHP, by the way.) I guess that the failsafe would be a simple str_replace (if that's also the best, do I need to do anything extra to make sure it works properly with unicode?) but that would involve me having to go through the XHTML DTD (or the above-referenced W3 page) carefully to figure out what characters to list in the search part of str_replace, so if this is the best way, has someone already done that so that I can steal, err, copy, it? (Incidentally, the character that caused the problem was U+000C, the 'formfeed', which (according to the W3 page) is valid HTML but invalid XHTML!)

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  • Generate a set of strings with maximum edit distance

    - by Kevin Jacobs
    Problem 1: I'd like to generate a set of n strings of fixed length m from alphabet s such that the minimum Levenshtein distance (edit distance) between any two strings is greater than some constant c. Obviously, I can use randomization methods (e.g., a genetic algorithm), but was hoping that this may be a well-studied problem in computer science or mathematics with some informative literature and an efficient algorithm or three. Problem 2: Same as above except that adjacent characters cannot repeat; the i'th character in each string may not be equal to the i+1'th character. E.g., 'CAT', 'AGA' and 'TAG' are allowed, 'GAA', 'AAT', and 'AAA' are not. Background: The basis for this problem is bioinformatic and involves designing unique DNA tags that can be attached to biologically derived DNA fragments and then sequenced using a fancy second generation sequencer. The goal is to be able to recognize each tag, allowing for random insertion, deletion, and substitution errors. The specific DNA sequencing technology has a relatively low error rate per base (~1%), but is less precise when a single base is repeated 2 or more times (motivating the additional constraints imposed in problem 2).

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  • How to make gcc on SUN calculate floating points the same way as in Linux

    - by Marina
    I have a project where I have to perform some mathematics calculations with double variables. The problem is that I get different results on SUN Solaris 9 and Linux. There are a lot of ways (explained here and other forums) how to make Linux work as Sun, but not the other way around. I cannot touch the Linux code, so it is only SUN I can change. Is there any way to make SUN to behave as Linux? The code I run(compile with gcc on both systems): int hash_func(char *long_id) { double product, lnum, gold; while (*long_id) lnum = lnum * 10.0 + (*long_id++ - '0'); printf("lnum => %20.20f\n", lnum); lnum = lnum * 10.0E-8; printf("lnum => %20.20f\n", lnum); gold = 0.6125423371582974; product = lnum * gold; printf("product => %20.20f\n", product); ... } if the input is 339886769243483 the output in Linux: lnum => 339886769243**483**.00000000000000000000 lnum => 33988676.9243**4829473495483398** product => 20819503.600158**59827399253845** When on SUN: lnum => 339886769243483.00000000000000000000 lnum => 33988676.92434830218553543091 product = 20819503.600158**60199928283691** Note: The result is not always different, moreover most of the times it is the same. Just 10 15-digit numbers out of 60000 have this problem. Please help!!!

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  • How to implement Horner's scheme for multivariate polynomials?

    - by gsreynolds
    Background I need to solve polynomials in multiple variables using Horner's scheme in Fortran90/95. The main reason for doing this is the increased efficiency and accuracy that occurs when using Horner's scheme to evaluate polynomials. I currently have an implementation of Horner's scheme for univariate/single variable polynomials. However, developing a function to evaluate multivariate polynomials using Horner's scheme is proving to be beyond me. An example bivariate polynomial would be: 12x^2y^2+8x^2y+6xy^2+4xy+2x+2y which would factorised to x(x(y(12y+8))+y(6y+4)+2)+2y and then evaluated for particular values of x & y. Research I've done my research and found a number of papers such as: staff.ustc.edu.cn/~xinmao/ISSAC05/pages/bulletins/articles/147/hornercorrected.pdf citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.40.8637&rep=rep1&type=pdf www.is.titech.ac.jp/~kojima/articles/B-433.pdf Problem However, I'm not a mathematician or computer scientist, so I'm having trouble with the mathematics used to convey the algorithms and ideas. As far as I can tell the basic strategy is to turn a multivariate polynomial into separate univariate polynomials and compute it that way. Can anyone help me? If anyone could help me turn the algorithms into pseudo-code that I can implement into Fortran myself, I would be very grateful.

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  • Maximum number of characters using keystrokes A, Ctrl+A, Ctrl+C and Ctrl+V

    - by munda
    This is an interview question from google. I am not able to solve it by myself. Can somebody shed some light? Write a program to print the sequence of keystrokes such that it generates the maximum number of character 'A's. You are allowed to use only 4 keys: A, Ctrl+A, Ctrl+C and Ctrl+V. Only N keystrokes are allowed. All Ctrl+ characters are considered as one keystroke, so Ctrl+A is one keystroke. For example, the sequence A, Ctrl+A, Ctrl+C, Ctrl+V generates two A's in 4 keystrokes. Ctrl+A is Select All Ctrl+C is Copy Ctrl+V is Paste I did some mathematics. For any N, using x numbers of A's , one Ctrl+A, one Ctrl+C and y Ctrl+V, we can generate max ((N-1)/2)2 number of A's. For some N M, it is better to use as many Ctrl+A's, Ctrl+C and Ctrl+V sequences as it doubles the number of A's. The sequence Ctrl+A, Ctrl+V, Ctrl+C will not overwrite the existing selection. It will append the copied selection to selected one.

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  • Would anybody recommend learning J/K/APL?

    - by ozan
    I came across J/K/APL a few months ago while working my way through some project euler problems, and was intrigued, to say the least. For every elegant-looking 20 line python solution I produced, there'd be a gobsmacking 20 character J solution that ran in a tenth of the time. I've been keen to learn some basic J, and have made a few attempts at picking up the vocabulary, but have found the learning curve to be quite steep. To those who are familiar with these languages, would you recommend investing some time to learn one (I'm thinking J in particular)? I would do so more for the purpose of satisfying my curiosity than for career advancement or some such thing. Some personal circumstances to consider, if you care to: I love mathematics, and use it daily in my work (as a mathematician for a startup) but to be honest I don't really feel limited by the tools that I use (like python + NumPy) so I can't use that excuse. I have no particular desire to work in the finance industry, which seems to be the main port of call for K users at least. Plus I should really learn C# as a next language as it's the primary language where I work. So practically speaking, J almost definitely shouldn't be the next language I learn. I'm reasonably familiar with MATLAB so using an array-based programming language wouldn't constitute a tremendous paradigm shift. Any advice from those familiar with these languages would be much appreciated.

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  • Vehicle License Plate Detection

    - by Ash
    Hey all Basically for my final project at university, I'm developing a vehicle license plate detection application. Now I consider myself an intermediate programmer, however my mathematics knowledge lacks anything above secondary school, therefore producing detection formulae is basically impossible. I've spend a good amount of time looking up academic papers such as: http://www.scribd.com/doc/266575/Detecting-Vehicle-License-Plates-in-Images http://www.cic.unb.br/~mylene/PI_2010_2/ICIP10/pdfs/0003945.pdf http://www.eurasip.org/Proceedings/Eusipco/Eusipco2007/Papers/d3l-b05.pdf When it comes to the maths, I'm lost. Due to this testing various graphic images proved productive, for example: to However this approach is only catered to that particular image, and if the techniques were applied to different images, I'm sure a different, most likely poorer conversion would occur. I've read about a formula called the bottom hat morphology transform, which according to the first does the following: "Basically, the trans- formation keeps all the dark details of the picture, and eliminates everything else (including bigger dark regions and light regions)." Sadly I can't find much information on this, however the image within the documentation near the end of the report shows it's effectiveness. I'm aware this is complicated and vast, I'd just appreciate a little advice, even in terms of what transformation techniques I should focus on developing, or algorithm regarding edge detection or pixel detection. Few things I need to add Developing in C Sharp Confining the project to UK registration plates only I can basically choose the images to convert as a demonstration Thanks

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  • Why doesn't java.lang.Number implement Comparable?

    - by Julien Chastang
    Does anyone know why java.lang.Number does not implement Comparable? This means that you cannot sort Numbers with Collections.sort which seems to me a little strange. Post discussion update: Thanks for all the helpful responses. I ended up doing some more research about this topic. The simplest explanation for why java.lang.Number does not implement Comparable is rooted in mutability concerns. For a bit of review, java.lang.Number is the abstract super-type of AtomicInteger, AtomicLong, BigDecimal, BigInteger, Byte, Double, Float, Integer, Long and Short. On that list, AtomicInteger and AtomicLong to do not implement Comparable. Digging around, I discovered that it is not a good practice to implement Comparable on mutable types because the objects can change during or after comparison rendering the result of the comparison useless. Both AtomicLong and AtomicInteger are mutable. The API designers had the forethought to not have Number implement Comparable because it would have constrained implementation of future subtypes. Indeed, AtomicLong and AtomicInteger were added in Java 1.5 long after java.lang.Number was initially implemented. Apart from mutability, there are probably other considerations here too. A compareTo implementation in Number would have to promote all numeric values to BigDecimal because it is capable of accommodating all the Number sub-types. The implication of that promotion in terms of mathematics and performance is a bit unclear to me, but my intuition finds that solution kludgy.

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  • When is the reintegrate option really necessary?

    - by Tor Hovland
    If you always sync a feature branch before you merge it back, why do you really have to use the --reintegrate option? The Subversion book says: When merging your branch back to the trunk, however, the underlying mathematics is quite different. Your feature branch is now a mishmosh of both duplicated trunk changes and private branch changes, so there's no simple contiguous range of revisions to copy over. By specifying the --reintegrate option, you're asking Subversion to carefully replicate only those changes unique to your branch. (And in fact, it does this by comparing the latest trunk tree with the latest branch tree: the resulting difference is exactly your branch changes!) So the --reintegrate option only merges the changes that are unique to the feature branch. But if you always sync before merge (which is a recommended practice, in order to deal with any conflicts on the feature branch), then the only changes between the branches are the changes that are unique to the feature branch, right? And if Subversion tries to merge code that is already on the target branch, it will just do nothing, right? In this blog post, Mark Phippard writes: http://blogs.open.collab.net/svn/2008/07/subversion-merg.html If we include those synched revisions, then we merge back changes that already exist in trunk. This yields unnecessary and confusing conflicts. Can somebody give me an example of when dropping reintegrate gives me unnecessary conflicts?

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