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  • What is the relationship between Turing Machine & Modern Computer ? [closed]

    - by smwikipedia
    I heard a lot that modern computers are based on Turing machine. I just cannot build a bridge between a conceptual Turing Machine and a modern computer. Could someone help me build this bridge? Below is my current understanding. I think the computer is a big general-purpose Turing machine. Each program we write is a small specific-purpose Turing machine. The classical Turing machine do its job based on the input and its current state inside and so do our programs. Let's take a running program (a process) as an example. We know that in the process's address space, there's areas for stack, heap, and code. A classical Turing machine doesn't have the ability to remember many things, so we borrow the concept of stack from the push-down automaton. The heap and stack areas contains the state of our specific-purpose Turing machine (our program). The code area represents the logic of this small Turing machine. And various I/O devices supply input to this Turing machine.

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  • Quadratic Bezier Curve: Calculate Tangent

    - by stefan.at.wpf
    I have a quadratic bezier curve and I want to calculate the slope of the tangent in a given point. For example, let it be the middlepoint of the quadratic bezier curve, therefore t=0.5 (please see the link below for a picture of this). I've calculated the first derivative of the formula for the quadratic bezier curve; however I get 400 as value for the slope, though it should be 0. Maybe I'm using the first derivative in a wrong way? I know I could also calculate the tangents using trigonometric functions; however I'd like to do it using the first derivative, shouldn't this be possible? Thanks for any hint! For clarification / please note: I'm interested in a general way to get the slope in a arbitrary given point on a quadratic bezier curve, not only to get the tangent in the start- and end point. A picture of my problem including the text above: http://cid-0432ee4cfe9c26a0.skydrive.live.com/self.aspx/%c3%96ffentlich/Quadratic%20Bezier%20Curve.pdf Thank you very much for any hint!

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  • Django Models / SQLAlchemy are bloated! Any truly Pythonic DB models out there?

    - by Luke Stanley
    "Make things as simple as possible, but no simpler." Can we find the solution/s that fix the Python database world? from someAmazingDB import * class Task (model): title = '' isDone = False db.taskList = [] #or db.taskList = expandableTypeCollection(Task) #not sure what this syntax would be db['taskList'].append(Task(title='Beat old sql interfaces',done=False)) db.taskList.append(Task('Illustrate different syntax modes',True)) #at this point it should autosave #we should be able to reload the console and access like: >> from someAmazingDB import * >> print 'Done tasks:' >> for task in db.taskList: >> if task.done: >> print task 'Illustrate different syntax modes' I'm a fan of Python, webPy and Cherry Py, and KISS in general. We're talking automatic Python to SQL type translation or NoSQL. We don't have to totally be SQL compatible! Just a scalable subset or ignore it! Re:model changes, it's ok to ask the developer when they try to change it or have a set of sensible defaults. Here is the challenge: The above code should work with very little modification or thinking required. Why must we put up with compromise when we know better? It's 2010, we should be able to code scalable, simple databases in our sleep. If you think this is important, please upvote!

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  • Python metaclass for enforcing immutability of custom types

    - by Mark Lehmacher
    Having searched for a way to enforce immutability of custom types and not having found a satisfactory answer I came up with my own shot at a solution in form of a metaclass: class ImmutableTypeException( Exception ): pass class Immutable( type ): ''' Enforce some aspects of the immutability contract for new-style classes: - attributes must not be created, modified or deleted after object construction - immutable types must implement __eq__ and __hash__ ''' def __new__( meta, classname, bases, classDict ): instance = type.__new__( meta, classname, bases, classDict ) # Make sure __eq__ and __hash__ have been implemented by the immutable type. # In the case of __hash__ also make sure the object default implementation has been overridden. # TODO: the check for eq and hash functions could probably be done more directly and thus more efficiently # (hasattr does not seem to traverse the type hierarchy) if not '__eq__' in dir( instance ): raise ImmutableTypeException( 'Immutable types must implement __eq__.' ) if not '__hash__' in dir( instance ): raise ImmutableTypeException( 'Immutable types must implement __hash__.' ) if _methodFromObjectType( instance.__hash__ ): raise ImmutableTypeException( 'Immutable types must override object.__hash__.' ) instance.__setattr__ = _setattr instance.__delattr__ = _delattr return instance def __call__( self, *args, **kwargs ): obj = type.__call__( self, *args, **kwargs ) obj.__immutable__ = True return obj def _setattr( self, attr, value ): if '__immutable__' in self.__dict__ and self.__immutable__: raise AttributeError( "'%s' must not be modified because '%s' is immutable" % ( attr, self ) ) object.__setattr__( self, attr, value ) def _delattr( self, attr ): raise AttributeError( "'%s' must not be deleted because '%s' is immutable" % ( attr, self ) ) def _methodFromObjectType( method ): ''' Return True if the given method has been defined by object, False otherwise. ''' try: # TODO: Are we exploiting an implementation detail here? Find better solution! return isinstance( method.__objclass__, object ) except: return False However, while the general approach seems to be working rather well there are still some iffy implementation details (also see TODO comments in code): How do I check if a particular method has been implemented anywhere in the type hierarchy? How do I check which type is the origin of a method declaration (i.e. as part of which type a method has been defined)?

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  • Implementing crossover in genetic programming

    - by Name
    Hi, I'm writing a genetic programming (GP) system (in C but that's a minor detail). I've read a lot of the literature (Koza, Poli, Langdon, Banzhaf, Brameier, et al) but there are some implementation details I've never seen explained. For example: I'm using a steady state population rather than a generational approach, primarily to use all of the computer's memory rather than reserve half for the interim population. Q1. In GP, as opposed to GA, when you perform crossover you select two parents but do you create one child or two, or is that a free choice you have? Q2. In steady state GP, as opposed to a generational system, what members of the population do the children created by crossover replace? This is what I haven't seen discussed. Is it the two parents, or is it two other, randomly-selected members? I can understand if it's the latter, and that you might use negative tournament selection to choose members to replace, but would that not create premature convergence? (After a crossover event the population contains the two original parents plus two children of those parents, and two other random members get removed. Elitism is inherent.) Q3. Is there a Web forum or mailing list focused on GP? Oddly I haven't found one. Yahoo's GP group is used almost exclusively for announcements, the Poli/Langdon Field Guide forum is almost silent, and GP discussions on general/game programming sites like gamedev.net are very basic. Thanks for any help you can provide!

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  • Reset.css and then a Set.css

    - by Sixfoot Studio
    I have, for a while now been using a reset.css file to reset everything before I start laying out my html designs. The reset is great in that it allows one to better control attributes such as margins, padding, line-height etc for all browsers. In essence the flatliner of css files. Now to get the heart beating again, I need a "set.css" file. So what I have done is created an Html file with all the possible elements on the page to then go and set the padding, margins etc of the h1, h2, p, td etc. I need some help with this as I am not sure what the defaults normally are. I had a look at the Firefox default css file that's used to generate all these attributes on a raw html file but it doesn't cover all the scenarios I could come up with when developing a site. Here's an example of the set.html file (a work in progress) which can be used as a lorem ipsum filler to add to your first page in a cms and then to style with a "set.css" file http://www.sixfoot.co.za/labs/Html-Css/set.html I'd appreciate it if someone knows if something like a set.css file exists or if someone could tell me what the general padding and margins are in cases like this when you have reset the css. Cheers, James

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  • Wrappers/law of demeter seems to be an anti-pattern...

    - by Robert Fraser
    I've been reading up on this "Law of Demeter" thing, and it (and pure "wrapper" classes in general) seem to generally be anti patterns. Consider an implementation class: class Foo { void doSomething() { /* whatever */ } } Now consider two different implementations of another class: class Bar1 { private static Foo _foo = new Foo(); public static Foo getFoo() { return _foo; } } class Bar2 { private static Foo _foo = new Foo(); public static void doSomething() { _foo.doSomething(); } } And the ways to call said methods: callingMethod() { Bar1.getFoo().doSomething(); // Version 1 Bar2.doSomething(); // Version 2 } At first blush, version 1 seems a bit simpler, and follows the "rule of Demeter", hide Foo's implementation, etc, etc. But this ties any changes in Foo to Bar. For example, if a parameter is added to doSomething, then we have: class Foo { void doSomething(int x) { /* whatever */ } } class Bar1 { private static Foo _foo = new Foo(); public static Foo getFoo() { return _foo; } } class Bar2 { private static Foo _foo = new Foo(); public static void doSomething(int x) { _foo.doSomething(x); } } callingMethod() { Bar1.getFoo().doSomething(5); // Version 1 Bar2.doSomething(5); // Version 2 } In both versions, Foo and callingMethod need to be changed, but in Version 2, Bar also needs to be changed. Can someone explain the advantage of having a wrapper/facade (with the exception of adapters or wrapping an external API or exposing an internal one).

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  • django shopping cart as a beginner

    - by Jacques Knie
    Hi, i'm quite new to django and trying to add a shopping cart to a simple webshop. What I need is a simple cart that can be filled and presents its content, which is then sent to the vendor via email. So Satchmo might be too big for this task. Therefore i chose django-cart (http://code.google.com/p/django-cart/) which causes some problems now. 1. Is django-cart the right thing? Or are there any better approaches to this task? 2. As I am a beginner even django-cart makes me struggle. I used the view and the template of the django-cart-website, but writing a form that can be used to add products to the cart took me hours. I probably need help in understanding the general layout of a shopping cart and its integration into a website. 3. Two more specific questions: Is it possible to dynamically populate a formfield in a template (e.g. with {{ object.id }})? Is django-cart able to change (update) the contents of a cart? I hope it's not too many questions at once. Thanks in advance Jacques

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  • Asymptotic complexity of a compiler

    - by Meinersbur
    What is the maximal acceptable asymptotic runtime of a general-purpose compiler? For clarification: The complexity of compilation process itself, not of the compiled program. Depending on the program size, for instance, the number of source code characters, statements, variables, procedures, basic blocks, intermediate language instructions, assembler instructions, or whatever. This is highly depending on your point of view, so this is a community wiki. See this from the view of someone who writes a compiler. Will the optimisation level -O4 ever be used for larger programs when one of its optimisations takes O(n^6)? Related questions: When is superoptimisation (exponential complexity or even incomputable) acceptable? What is acceptable for JITs? Does it have to be linear? What is the complexity of established compilers? GCC? VC? Intel? Java? C#? Turbo Pascal? LCC? LLVM? (Reference?) If you do not know what asymptotic complexity is: How long are you willing to wait until the compiler compiled your project? (scripting languages excluded)

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  • Linking session state between servlets and EJBs?

    - by wilth
    Hello, I have servlets (in a web module) that access stateless EJB beans (in an EJB module). The EJB module is built using SEAM. Users can have different roles and the EJB services check this using Seam's Identity. I also use a customized Authenticator (although this might not be relevant here). I noticed problems with this approach and I'm suspecting that the session context in the servlets is not "linked" with the session context in the EJB beans. What I think happens is something like: User Joe access servlet A and is assigned Session W1. Servlet A calls a login function on an EJB, using the EJB session E1. Later, user Mary accesses servlet A and is assigned Session W2. When calling the EJBs, however, the EJB session E1 is used and therefore Mary is authenticated as Joe. What also happens is that when Joe is calling the servlet twice in rapid succession, the same session W1 is used, but two different sessions E1 and E2 in the business layer, causing errors. I might be wrong in my suspicion, but maybe I'm actually expecting these "sessions" to be linked together while they in fact are not. If this is true, is there any way of achieving this? I could - of course - use stateful beans and save the authentication information in the beans, but this would break the "Identity" concept of Seam (and in general, it would be preferable to be able to use the Session context in my EJB beans). Any help and pointers are very welcome - thanks! Technology: EJB3, Seam 2.1.2. The servlets are actually the server-side of a GWT app, although I don't think this matters much. I'm using JBoss 5.

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  • paypal address1 HTML name doensnt work?

    - by ajsie
    i use this code to send the customer to the paypals payment page: <form action="https://www.paypal.com/cgi-bin/webscr" method="post"> <input type='hidden' name='cmd' value='_cart' /> <input type='hidden' name='upload' value='1' /> <input type="hidden" name="business" value="[email protected]"> <input type="hidden" name="currency_code" value="SEK"> <input type="hidden" name="return" value="http://freelanceswitch.com/payment-complete/"> <input type="hidden" name="item_number_1" value="01 - General Payment"> <input type="hidden" name="item_name_1" size="45"> <input type="hidden" name="amount_1" size="45"> <input type="hidden" name="item_number_2" value="01 - Bonus Payment"> <input type="hidden" name="item_name_2" size="45"> <input type="hidden" name="amount_2" size="45"> <!-- PREPOPULATING FIELDS --> <input type='hidden' name='address1' value='Open Bridge street 19' /> <input type='hidden' name='address2' value='Easter heaven garden 12' /> <input type='hidden' name='first_name' value='Peter' /> <input type='hidden' name='last_name' value='Hansen' /> <input type="submit" name="Submit" value="Submit"> </form> everything works except the address1 and address2 in PREPOPULATING FIELDS. the fields for the Billing Address Line 1 and Billing Address Line 2 are empty. anyone knows why?

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  • What is the correct date format for a Date column in YUI DataTable ?

    - by giulio
    I have produced a data table. All the columns are sortable. It has a date in one column which I formatted dd/mm/yyyy hh:mm:ss . This is different from the default format as defined in the doco, but I should be able to define my own format for non-american formats. (See below) The DataTable class provides a set of built-in static functions to format certain well-known types of data. In your Column definition, if you set a Column's formatter to YAHOO.widget.DataTable.formatDate, that function will render data of type Date with the default syntax of "MM/DD/YYYY". If you would like to bypass a built-in formatter in favor of your own, you can point a Column's formatter to a custom function that you define. The table is generated from HTML Markup, so the data is held within "" tags. This gives me some more clues about compatible string dates for javascript: In general, the RecordSet expects to hold data in native JavaScript types. For instance, a date is expected to be a JavaScript Date instance, not a string like "4/26/2005" in order to sort properly. Converting data types as data comes into your RecordSet is enabled through the parser property in the fields array of your DataSource's responseSchema I suspect that the I'm missing something in the date format. So what is an acceptable string date for javascript, that Yui dataTable will recognise, given that I want format it as "dd/mm/yyyy hh:mm:ss" ?

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  • TeamCity and pending Git merge branch commit keeps build with failed tests

    - by Vladimir
    We use TeamCity for continuous integration and Git for source control. Generally it works pretty well - convenient, modern and good us quick feedback when tests fails. There is a strange behavior related to Git merge specifics. Here are steps of the case: First developer pulls from master repo. Second developer pulls from master repo. First developer makes commit A locally. Second developer makes commit B locally; Second developer pushes commit B. First developer want to push commit A but unable because he have to pull commit B first. First developer pull's from remote reposity. First developer pushes commit A and generated merge branch commit. The history of commits in master repo is following: B second developer A first developer merge branch first developer. Now let's assume that Second Developer fixed some failing tests in his commit B. What TeamCity will do is following: Commit B arrives - TeamCity makes build #1 with all tests passed Commit A arrives - TeamCity makes build #2 (without commit B) test bar becomes Red! TeamCity thought that Pending "Merge Branch" commit doesn't contain any changes (any new files) - but it actually does contain the merge of commit B, so the TeamCity don't want to make new build here and make tests green. Here are two problems: 1. In our case we have failed tests returning back in second commit (commit A) 2. TeamCity don't want to make a new build and make tests back green. Does anybody know how to fix both of this problems. I consider some reasonable general approach.

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  • How to keep only duplicates efficiently?

    - by Marc Eaddy
    Given an STL vector, I'd like an algorithm that outputs only the duplicates in sorted order, e.g., INPUT : { 4, 4, 1, 2, 3, 2, 3 } OUTPUT: { 2, 3, 4 } The algorithm is trivial, but the goal is to make it as efficient as std::unique(). My naive implementation modifies the container in-place: My naive implementation: void keep_duplicates(vector<int>* pv) { // Sort (in-place) so we can find duplicates in linear time sort(pv->begin(), pv->end()); vector<int>::iterator it_start = pv->begin(); while (it_start != pv->end()) { size_t nKeep = 0; // Find the next different element vector<int>::iterator it_stop = it_start + 1; while (it_stop != pv->end() && *it_start == *it_stop) { nKeep = 1; // This gets set redundantly ++it_stop; } // If the element is a duplicate, keep only the first one (nKeep=1). // Otherwise, the element is not duplicated so erase it (nKeep=0). it_start = pv->erase(it_start + nKeep, it_stop); } } If you can make this more efficient, elegant, or general, please let me know. For example, a custom sorting algorithm, or copy elements in the 2nd loop to eliminate the erase() call.

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  • Dividing sections inside an omp parallel for : OpenMP

    - by Sayan Ghosh
    Hi, I have a situation like: #pragma omp parallel for private(i, j, k, val, p, l) for (i = 0; i < num1; i++) { for (j = 0; j < num2; j++) { for (k = 0; k < num3; k++) { val = m[i + j*somenum + k*2] if (val != 0) for (l = start; l <= end; l++) { someFunctionThatWritesIntoGlobalArray((i + l), j, k, (someFunctionThatGetsValueFromAnotherArray((i + l), j, k) * val)); } } } for (p = 0; p < num4; p++) { m[p] = 0; } } Thanks for reading, phew! Well I am noticing a very minor difference in the results (0.999967[omp] against 1[serial]), when I use the above (which is 3 times faster) against the serial implementation. Now I know I am doing a mistake here...especially the connection between loops is evident. Is it possible to parallelize this using omp sections? I tried some options like making shared(p) {doing this, I got correct values, as in the serial form}, but there was no speedup then. Any general advice on handling openmp pragmas over a slew of for loops would also be great for me!

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  • Haskell Linear Algebra Matrix Library for Arbitrary Element Types

    - by Johannes Weiß
    I'm looking for a Haskell linear algebra library that has the following features: Matrix multiplication Matrix addition Matrix transposition Rank calculation Matrix inversion is a plus and has the following properties: arbitrary element (scalar) types (in particular element types that are not Storable instances). My elements are an instance of Num, additionally the multiplicative inverse can be calculated. The elements mathematically form a finite field (??2256). That should be enough to implement the features mentioned above. arbitrary matrix sizes (I'll probably need something like 100x100, but the matrix sizes will depend on the user's input so it should not be limited by anything else but the memory or the computational power available) as fast as possible, but I'm aware that a library for arbitrary elements will probably not perform like a C/Fortran library that does the work (interfaced via FFI) because of the indirection of arbitrary (non Int, Double or similar) types. At least one pointer gets dereferenced when an element is touched (written in Haskell, this is not a real requirement for me, but since my elements are no Storable instances the library has to be written in Haskell) I already tried very hard and evaluated everything that looked promising (most of the libraries on Hackage directly state that they wont work for me). In particular I wrote test code using: hmatrix, assumes Storable elements Vec, but the documentation states: Low Dimension : Although the dimensionality is limited only by what GHC will handle, the library is meant for 2,3 and 4 dimensions. For general linear algebra, check out the excellent hmatrix library and blas bindings I looked into the code and the documentation of many more libraries but nothing seems to suit my needs :-(. Update Since there seems to be nothing, I started a project on GitHub which aims to develop such a library. The current state is very minimalistic, not optimized for speed at all and only the most basic functions have tests and therefore should work. But should you be interested in using or helping out developing it: Contact me (you'll find my mail address on my web site) or send pull requests.

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  • JQUERY, AutoSuggest that doesn't kill the Server on ever keyup

    - by nobosh
    I'm working to build a JQUERY enabled AutoSuggest plugin, inspired by Apple's spotlight. Here is the general code: $(document).ready(function() { $('#q').bind('keyup', function() { if( $(this).val().length == 0) { // Hide the q-suggestions box $('#q-suggestions').fadeOut(); } else { // Show the AJAX Spinner $("#q").css("background-image","url(/images/ajax-loader.gif)"); $.ajax({ url: '/search/spotlight/', data: {"q": $(this).val()}, success: function(data) { $('#q-suggestions').fadeIn(); // Show the q-suggestions box $('#q-suggestions').html(data); // Fill the q-suggestions box // Hide the AJAX Spinner $("#q").css("background-image","url(/images/icon-search.gif)"); } }); } }); The issue I want to solve well & elegantly, is not killing the sever. Right now the code above hits the server every time you type a key and does not wait for you to essentially finish typing. What's the best way to solve this? A. Kill previous AJAX request? B. Some type of AJAX caching? C. Adding some type of delay to only submit .AJAX() when the person has stopped typing for 300ms or so? Thanks

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  • Problem Linking Boost Filesystem Library in Microsoft Visual C++

    - by Scott
    Hello. I am having trouble getting my project to link to the Boost (version 1.37.0) Filesystem lib file in Microsoft Visual C++ 2008 Express Edition. The Filesystem library is not a header-only library. I have been following the Getting Started on Windows guide posted on the official boost web page. Here are the steps I have taken: I used bjam to build the complete set of lib files using: bjam --build-dir="C:\Program Files\boost\build-boost" --toolset=msvc --build-type=complete I copied the /libs directory (located in C:\Program Files\boost\build-boost\boost\bin.v2) to C:\Program Files\boost\boost_1_37_0\libs. In Visual C++, under Project Properties Additional Library Directories I added these paths: C:\Program Files\boost\boost_1_37_0\libs C:\Program Files\boost\boost_1_37_0\libs\filesystem\build\msvc-9.0express\debug\link-static\threading-multi I added the second one out of desperation. It is the exact directory where libboost_system-vc90-mt-gd-1_37.lib resides. In Configuration Properties C/C++ General Additional Include Directories I added the following path: C:\Program Files\boost\boost_1_37_0 Then, to put the icing on the cake, under Tools Options VC++ Directories Library files, I added the same directories mentioned in step 3. Despite all this, when I build my project I get the following error: fatal error LNK1104: cannot open file 'libboost_system-vc90-mt-gd-1_37.lib' Additionally, here is the code that I am attempting to compile as well as a screen shot of the aformentioned directory where the (assumedly correct) lib file resides: #include "boost/filesystem.hpp" // includes all needed Boost.Filesystem declarations #include <iostream> // for std::cout using boost::filesystem; // for ease of tutorial presentation; // a namespace alias is preferred practice in real code using namespace std; int main() { cout << "Hello, world!" << endl; return 0; } Can anyone help me out? Let me know if you need to know anything else. As always, thanks in advance.

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  • How to compile a C DLL for 64 bit with Visual Studio 2010?

    - by Daren Thomas
    I have a DLL written in C in source code. This is the code for the General Polygon Clipper (in case you are interested). I'm using it in a C# project via the C# wrapper provided on the homepage. This comes with a precompiled DLL. Since switching to a 64bit Development machine with Visual Studio 2010 and Windows 7 64 bit, the application won't run anymore. This is the error I get: An attempt was made to load a program with an incorrect format. This is because of DLLImporting the 32bit gpc.dll, as I have gathered from stuff found on the web. I assume this will all go away if I recompile the DLL to 64bit, but can't for the love of me figure out how to do so. My C skills are basic, in that I can write a C program with the GNU tools, but have no experience with various compilers / processors / IDEs etc. I believe I could port this to C#. By that I mean I trust myself to actually pull it off. But I'd prefer not to, since it is a lot of work that I'd prefer a compiler to do for me ;)

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  • 2D Ball Collisions with Corners

    - by Aaron
    I'm trying to write a 2D simulation of a ball that bounces off of fixed vertical and horizontal walls. Simulating collisions with the faces of the walls was pretty simple--just negate the X-velocity for a vertical wall or the Y-velocity for a horizontal wall. The problem is that the ball can also collide with the corners of the walls, where a horizontal wall meets with a vertical wall. I have already figured out how to detect when a collision with a corner is occurring. My question is how the ball should react to this collision--that is, how its X and Y velocities will change as a result. Here's a list of what I already know or know how to find: *The X and Y coordinates of the ball's center during the frame when a collision is detected *The X and Y components of the ball's velocity *The X and Y coordinates of the corner *The angle between the ball's center and the corner *The angle in which the ball is traveling just before the collision *The amount that the ball is overlapping the corner when the collision is detected I'm guessing that it's best to pretend that the corner is an infinitely small circle, so I can treat a collision between the ball and that circle as if the ball were colliding with a wall that runs tangent to the circles at the point of collision. It seems to me that all I need to do is rotate the coordinate system to line up with this imaginary wall, reverse the X component of the ball's velocity under this system, and rotate the coordinates back to the original system. The problem is that I have no idea how to program this. By the way, this is an ideal simulation. I'm not taking anything like friction or the ball's rotation into account. I'm using Objective-C, but I'd really just like a general algorithm or some advice. Many thanks if anyone can help!

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  • SIMPLE PHP MVC Framework!

    - by Allen
    I need a simple and basic MVC example to get me started. I dont want to use any of the available packaged frameworks. I am in need of a simple example of a simple PHP MVC framework that would allow, at most, the basic creation of a simple multi-page site. I am asking for a simple example because I learn best from simple real world examples. Big popular frameworks (such as code ignighter) are to much for me to even try to understand and any other "simple" example I have found are not well explained or seem a little sketchy in general. I should add that most examples of simple MVC frameworks I see use mod_rewrite (for URL routing) or some other Apache-only method. I run PHP on IIS. I need to be able to understand a basic MVC framework, so that I could develop my own that would allow me to easily extend functionality with classes. I am at the point where I understand basic design patterns and MVC pretty well. I understand them in theory, but when it comes down to actually building a real world, simple, well designed MVC framework in PHP, i'm stuck. I would really appreciate some help! Edit: I just want to note that I am looking for a simple example that an experienced programmer could whip up in under an hour. I mean simple as in bare bones simple. I dont want to use any huge frameworks, I am trying to roll my own. I need a decent SIMPLE example to get me going.

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  • SQL Stored Queries - use result of query as boolean based on existence of records

    - by Christian Mann
    Just getting into SQL stored queries right now... anyway, here's my database schema (simplified for YOUR convenience): member ------ id INT PK board ------ id INT PK officer ------ id INT PK If you're into OOP, Officer Inherits Board Inherits Member. In other words, if someone is listed on the officer table, s/he is listed on the board table and the member table. I want to find out the highest privilege level someone has. So far my SP looks like this: DELIMITER // CREATE PROCEDURE GetAuthLevel(IN targetID MEDIUMINT) BEGIN IF SELECT `id` FROM `member` WHERE `id` = targetID; THEN IF SELECT `id` FROM `board` WHERE `id` = targetID; THEN IF SELECT `id` FROM `officer` WHERE `id` = targetID; THEN RETURN 3; /*officer*/ ELSE RETURN 2; /*board member*/ ELSE RETURN 1; /*general member*/ ELSE RETURN 0; /*not a member*/ END // DELIMITER ; The exact text of the error is #1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'SELECT id FROM member WHERE id = targetID; THEN IF SEL' at line 4 I suspect the issue is in the arguments for the IF blocks. What I want to do is return true if the result-set is at least one -- i.e. the id was found in the table. Do any of you guys see anything to do here, or should I reconsider my database design into this:? person ------ id INT PK level SMALLINT

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  • Date from String using NSDateFormatter regardless 12h-24h setting

    - by maxf99
    Hello everybody, Today my question is about date formats and strings. My application downloads some strings representing dates from the internet. The date format is always like this: "2010-05-24 at 20:45" I need to convert this string into an NSDate object in order to perform some date manipulations. I tried this code: NSString * dateString = @"2010-05-24 at 20:45" // actually downloaded from the internet NSDateFormatter * myDateFormatter = [[NSDateFormatter alloc] init]; [myDateFormatter setDateFormat:@"yyyy-MM-dd 'at' HH:mm"]; NSDate * dateFromString = [myDateFormatter dateFromString:dateString]; This seems to work perfectly fine as long as the iPhone is set to 24h clock. As long as I switch to 12h clock in the general settings the NSDate object is not created (and the application happily crashes) I have read others having similar problems but I don't seem to find a solution. Now the questions: It doesn't make sense to me that the NSDateFormatter is sensible to user settings as long as I am specifying which format it is supposed to use to parse the string (which is not modifiable because it comes from the web), what's the use of checking user settings? More important, how can I get my task performed (to get an NSDate object from the string regardless the user settings)?

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  • Backreferences in lookbehind

    - by polygenelubricants
    Can you use backreferences in a lookbehind? Let's say I want to split wherever behind me a character is repeated twice. String REGEX1 = "(?<=(.)\\1)"; // DOESN'T WORK! String REGEX2 = "(?<=(?=(.)\\1)..)"; // WORKS! System.out.println(java.util.Arrays.toString( "Bazooka killed the poor aardvark (yummy!)" .split(REGEX2) )); // prints "[Bazoo, ka kill, ed the poo, r aa, rdvark (yumm, y!)]" Using REGEX2 (where the backreference is in a lookahead nested inside a lookbehind) works, but REGEX1 gives this error at run-time: Look-behind group does not have an obvious maximum length near index 8 (?<=(.)\1) ^ This sort of make sense, I suppose, because in general the backreference can capture a string of any length (if the regex compiler is a bit smarter, though, it could determine that \1 is (.) in this case, and therefore has a finite length). So is there a way to use a backreference in a lookbehind? And if there isn't, can you always work around it using this nested lookahead? Are there other commonly-used techniques?

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  • Mocking with Boost::Test

    - by Billy ONeal
    Hello everyone :) I'm using the Boost::Test library for unit testing, and I've in general been hacking up my own mocking solutions that look something like this: //In header for clients struct RealFindFirstFile { static HANDLE FindFirst(LPCWSTR lpFileName, LPWIN32_FIND_DATAW lpFindFileData) { return FindFirstFile(lpFileName, lpFindFileData); }; }; template <typename FirstFile_T = RealFindFirstFile> class DirectoryIterator { //.. Implementation } //In unit tests (cpp) #define THE_ANSWER_TO_LIFE_THE_UNIVERSE_AND_EVERYTHING 42 struct FakeFindFirstFile { static HANDLE FindFirst(LPCWSTR lpFileName, LPWIN32_FIND_DATAW lpFindFileData) { return THE_ANSWER_TO_LIFE_THE_UNIVERSE_AND_EVERYTHING; }; }; BOOST_AUTO_TEST_CASE( MyTest ) { DirectoryIterator<FakeFindFirstFile> LookMaImMocked; //Test } I've grown frustrated with this because it requires that I implement almost everything as a template, and it is a lot of boilerplate code to achieve what I'm looking for. Is there a good method of mocking up code using Boost::Test over my Ad-hoc method? I've seen several people recommend Google Mock, but it requires a lot of ugly hacks if your functions are not virtual, which I would like to avoid. Oh: One last thing. I don't need assertions that a particular piece of code was called. I simply need to be able to inject data that would normally be returned by Windows API functions.

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