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  • Templated << friend not working when in interrelationship with other templated union types

    - by Dwight
    While working on my basic vector library, I've been trying to use a nice syntax for swizzle-based printing. The problem occurs when attempting to print a swizzle of a different dimension than the vector in question. In GCC 4.0, I originally had the friend << overloaded functions (with a body, even though it duplicated code) for every dimension in each vector, which caused the code to work, even if the non-native dimension code never actually was called. This failed in GCC 4.2. I recently realized (silly me) that only the function declaration was needed, not the body of the code, so I did that. Now I get the same warning on both GCC 4.0 and 4.2: LINE 50 warning: friend declaration 'std::ostream& operator<<(std::ostream&, const VECTOR3<TYPE>&)' declares a non-template function Plus the five identical warnings more for the other function declarations. The below example code shows off exactly what's going on and has all code necessary to reproduce the problem. #include <iostream> // cout, endl #include <sstream> // ostream, ostringstream, string using std::cout; using std::endl; using std::string; using std::ostream; // Predefines template <typename TYPE> union VECTOR2; template <typename TYPE> union VECTOR3; template <typename TYPE> union VECTOR4; typedef VECTOR2<float> vec2; typedef VECTOR3<float> vec3; typedef VECTOR4<float> vec4; template <typename TYPE> union VECTOR2 { private: struct { TYPE x, y; } v; struct s1 { protected: TYPE x, y; }; struct s2 { protected: TYPE x, y; }; struct s3 { protected: TYPE x, y; }; struct s4 { protected: TYPE x, y; }; struct X : s1 { operator TYPE() const { return s1::x; } }; struct XX : s2 { operator VECTOR2<TYPE>() const { return VECTOR2<TYPE>(s2::x, s2::x); } }; struct XXX : s3 { operator VECTOR3<TYPE>() const { return VECTOR3<TYPE>(s3::x, s3::x, s3::x); } }; struct XXXX : s4 { operator VECTOR4<TYPE>() const { return VECTOR4<TYPE>(s4::x, s4::x, s4::x, s4::x); } }; public: VECTOR2() {} VECTOR2(const TYPE& x, const TYPE& y) { v.x = x; v.y = y; } X x; XX xx; XXX xxx; XXXX xxxx; // Overload for cout friend ostream& operator<<(ostream& os, const VECTOR2<TYPE>& toString) { os << "(" << toString.v.x << ", " << toString.v.y << ")"; return os; } friend ostream& operator<<(ostream& os, const VECTOR3<TYPE>& toString); friend ostream& operator<<(ostream& os, const VECTOR4<TYPE>& toString); }; template <typename TYPE> union VECTOR3 { private: struct { TYPE x, y, z; } v; struct s1 { protected: TYPE x, y, z; }; struct s2 { protected: TYPE x, y, z; }; struct s3 { protected: TYPE x, y, z; }; struct s4 { protected: TYPE x, y, z; }; struct X : s1 { operator TYPE() const { return s1::x; } }; struct XX : s2 { operator VECTOR2<TYPE>() const { return VECTOR2<TYPE>(s2::x, s2::x); } }; struct XXX : s3 { operator VECTOR3<TYPE>() const { return VECTOR3<TYPE>(s3::x, s3::x, s3::x); } }; struct XXXX : s4 { operator VECTOR4<TYPE>() const { return VECTOR4<TYPE>(s4::x, s4::x, s4::x, s4::x); } }; public: VECTOR3() {} VECTOR3(const TYPE& x, const TYPE& y, const TYPE& z) { v.x = x; v.y = y; v.z = z; } X x; XX xx; XXX xxx; XXXX xxxx; // Overload for cout friend ostream& operator<<(ostream& os, const VECTOR3<TYPE>& toString) { os << "(" << toString.v.x << ", " << toString.v.y << ", " << toString.v.z << ")"; return os; } friend ostream& operator<<(ostream& os, const VECTOR2<TYPE>& toString); friend ostream& operator<<(ostream& os, const VECTOR4<TYPE>& toString); }; template <typename TYPE> union VECTOR4 { private: struct { TYPE x, y, z, w; } v; struct s1 { protected: TYPE x, y, z, w; }; struct s2 { protected: TYPE x, y, z, w; }; struct s3 { protected: TYPE x, y, z, w; }; struct s4 { protected: TYPE x, y, z, w; }; struct X : s1 { operator TYPE() const { return s1::x; } }; struct XX : s2 { operator VECTOR2<TYPE>() const { return VECTOR2<TYPE>(s2::x, s2::x); } }; struct XXX : s3 { operator VECTOR3<TYPE>() const { return VECTOR3<TYPE>(s3::x, s3::x, s3::x); } }; struct XXXX : s4 { operator VECTOR4<TYPE>() const { return VECTOR4<TYPE>(s4::x, s4::x, s4::x, s4::x); } }; public: VECTOR4() {} VECTOR4(const TYPE& x, const TYPE& y, const TYPE& z, const TYPE& w) { v.x = x; v.y = y; v.z = z; v.w = w; } X x; XX xx; XXX xxx; XXXX xxxx; // Overload for cout friend ostream& operator<<(ostream& os, const VECTOR4& toString) { os << "(" << toString.v.x << ", " << toString.v.y << ", " << toString.v.z << ", " << toString.v.w << ")"; return os; } friend ostream& operator<<(ostream& os, const VECTOR2<TYPE>& toString); friend ostream& operator<<(ostream& os, const VECTOR3<TYPE>& toString); }; // Test code int main (int argc, char * const argv[]) { vec2 my2dVector(1, 2); cout << my2dVector.x << endl; cout << my2dVector.xx << endl; cout << my2dVector.xxx << endl; cout << my2dVector.xxxx << endl; vec3 my3dVector(3, 4, 5); cout << my3dVector.x << endl; cout << my3dVector.xx << endl; cout << my3dVector.xxx << endl; cout << my3dVector.xxxx << endl; vec4 my4dVector(6, 7, 8, 9); cout << my4dVector.x << endl; cout << my4dVector.xx << endl; cout << my4dVector.xxx << endl; cout << my4dVector.xxxx << endl; return 0; } The code WORKS and produces the correct output, but I prefer warning free code whenever possible. I followed the advice the compiler gave me (summarized here and described by forums and StackOverflow as the answer to this warning) and added the two things that supposedly tells the compiler what's going on. That is, I added the function definitions as non-friends after the predefinitions of the templated unions: template <typename TYPE> ostream& operator<<(ostream& os, const VECTOR2<TYPE>& toString); template <typename TYPE> ostream& operator<<(ostream& os, const VECTOR3<TYPE>& toString); template <typename TYPE> ostream& operator<<(ostream& os, const VECTOR4<TYPE>& toString); And, to each friend function that causes the issue, I added the <> after the function name, such as for VECTOR2's case: friend ostream& operator<< <> (ostream& os, const VECTOR3<TYPE>& toString); friend ostream& operator<< <> (ostream& os, const VECTOR4<TYPE>& toString); However, doing so leads to errors, such as: LINE 139: error: no match for 'operator<<' in 'std::cout << my2dVector.VECTOR2<float>::xxx' What's going on? Is it something related to how these templated union class-like structures are interrelated, or is it due to the unions themselves? Update After rethinking the issues involved and listening to the various suggestions of Potatoswatter, I found the final solution. Unlike just about every single cout overload example on the internet, I don't need access to the private member information, but can use the public interface to do what I wish. So, I make a non-friend overload functions that are inline for the swizzle parts that call the real friend overload functions. This bypasses the issues the compiler has with templated friend functions. I've added to the latest version of my project. It now works on both versions of GCC I tried with no warnings. The code in question looks like this: template <typename SWIZZLE> inline typename EnableIf< Is2D< typename SWIZZLE::PARENT >, ostream >::type& operator<<(ostream& os, const SWIZZLE& printVector) { os << (typename SWIZZLE::PARENT(printVector)); return os; } template <typename SWIZZLE> inline typename EnableIf< Is3D< typename SWIZZLE::PARENT >, ostream >::type& operator<<(ostream& os, const SWIZZLE& printVector) { os << (typename SWIZZLE::PARENT(printVector)); return os; } template <typename SWIZZLE> inline typename EnableIf< Is4D< typename SWIZZLE::PARENT >, ostream >::type& operator<<(ostream& os, const SWIZZLE& printVector) { os << (typename SWIZZLE::PARENT(printVector)); return os; }

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  • OO design - car rental

    - by gkid123
    AnHow would you implement the following car hierarchy along with the accessor functions and a CarRental class which contains the container to store them? A car rental company wants to keep track of its cars. Each vehicle has a license plate and a brand. Currently the company has SUV and Sedans. SUV have an optional third row seat, sedan’s have an optional sport package. Each car can be queried to inquire the number of passengers it can carry.

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  • How does Google App Engine precompile Java ?

    - by Thilo
    App Engine uses a "precompilation" process with the Java bytecode of an app to enhance the performance of the app in the Java runtime environment. Precompiled code functions identically to the original bytecode. Is there any detailed information what this does?

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  • Objective-C++ compiles for iPhone, but not simulator

    - by John Smith
    I have a C++ library I want to add to my iphone project. In one header file I declare @class a { cppvirtualclass V; } This compiles fine for the iPhone device with Release settings. However it refuses to compile for the Simulator with or without debug info. It give the error error: type 'V' has virtual member functions. Is there a way out of this or do I have to define only concrete C++ classes?

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  • Java HashSet key/value pair

    - by harley
    Why does Java not provide functions to get at the key/value pairs in a HashSet like in Hashtable? It seems like a real pain to have to iterate over it every time you need to get at something. Or am I just a newb missing something?

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  • PHP invalid image's and error handling

    - by Emdiesse
    Using PHP's Image and GD functions you can use the following method to finally output the php image imagepng($image); Sometimes, for whatever reason the image may not be displayed typically the error is not with the image but with the actual php functions not executing successfully. However this causes a blank image to be returned which doesn't help me. What I want to know is, is there a way to detect a blank or an invalid image and create a new image, write the errors to the new image using imagestring() and then display this new (debug) image instead. for example, a successfully displayed image with no errors: $image = imagecreate(256, 256); //create image imagecolortransparent($image, $BLUE); //set transparent imagefilledrectangle($image, 0, 0, 256, 256, $BLUE); //fill with 'transparent colour' //Draw a border round the image imageline($image, 0, 0, 0, 255, $Black); imageline($image, 0, 0, 255, 0, $Black); imageline($image, 255, 0, 255, 255, $Black); imageline($image, 0, 255, 255, 255, $Black); imagestring($image, 1, 10, 10, "I am an image!", $Black); imagepng($image); imagedestroy($image); but if I then introduce some errors in the php script that may or may not be to do with the actual image creation then the php script fails and the image will not be visible... $image = imagecreate(256, 256); //create image imagecolortransparent($image, $BLUE); //set transparent imagefilledrectangle($image, 0, 0, 256, 256, $BLUE); //fill with 'transparent colour' //Draw a border round the image imageline($image, 0, 0, 0, 255, $Black); imageline($image, 0, 0, 255, 0, $Black); imageline($image, 255, 0, 255, 255, $Black); imageline($image, 0, 255, 255, 255, $Black); imagestring($image, 1, 10, 10, "I am an image!", $Black); /* I am here to cause problems with the php script ** and cause the execution to fail, I am a function ** that does't exist... ** ** and I am missing a semi colon! ;)*/ non_existant_function() imagepng($image); imagedestroy($image); At this point I want to create a new image like above but in replacement of the I am an image! text I would put the actual error that has occured.

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  • wait_fences: failed to receive reply: 10004003 solution:not found.

    - by amy
    I am getting this error message,Whenever I show alertview in function : (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated { and then handling the click actio in : -(void)alertView:(UIAlertView *)alert clickedButtonAtIndex:(NSInteger)buttonIndex I saw all related posts but however didn't get any solution to this coz i dont have any keyboards on. I am only using navigation functions ans alertview inside it. App is also crash due to this problem. any help will highly appreciated.

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  • Alternative to System.Web.HttpUtility.HtmlEncode/Decode?

    - by Jörg Battermann
    Is there any 'slimmer' alternative to the System.Web.HttpUtility.HtmlEncode/.Decode functions in .net 3.5 (sp1)? A separate library is fine.. or even 'wanted', at least something that does not pull in a 'whole new world' of dependencies that System.Web requires. I only want to convert a normal string into its xml/xhtml compliant equivalent (& back).

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  • Java: JPQL date function to add a time period to another date

    - by bguiz
    SELECT x FROM SomeClass WHERE x.dateAtt BETWEEN CURRENT_DATE AND (CURRENT_DATE + 1 MONTH) In the above JPQL statement, SomeClass has a memebr dateAttr, which is a java.util.Date and has a @Temporal(javax.persistence.TemporalType.DATE) annotation. I need a way to do the (CURRENT_DATE + 1 MONTH) bit - it is obviously wrong in its current state - but cannot find the doc with the date function for JPQL. Can anyone point me in the direction of a doc that documents JPQL date functions (and also how to do this particular query)?

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  • MinGW/G++/g95 link problem - libf95 undefined reference to `MAIN_'

    - by pivakaka
    Hi folks, Summing up, my problem consists on compiling g95 objects inside a C++ application. Actually, I'm constructing an interface for an old fortran program. For this task, I'm using the wxWidgets GUI library, and calling fortran subroutines when necessary. At the beginning, I was developing the entire project compiling my fortran files with gfortran (which comes with GCC) and linking them with my app by the g++ -o... command. Everything was working fine but some numbers values calculated by my fotran subroutines returned NAN values. Doing some research, I realized that compiling my fortran files with gfortran with the -m32 flag, generates this NAN values problem. Although compiling with -m64 flag, my code works properly well. The only trouble here is that my App should be 32bits and then I tryed another compiller. Here I found g95 Fortran compiler, which compiles my fortran code and gives the right output on a 32bits environment. But when I'm trying to link these g95 objects into my program I see this following error: g++ -oCyclonTechTower.exe src\fortran\Modulo_Global.o src\fortran\Prop_Fisicas.o src\fortran\inversa.o src\fortran\tower.o src\fortran\PredadeCarga.o src\fortran\gota.o src\fortran\tadi.o src\view\SimulationORSATCustomDialog.o src\view\SimulationChildGUIFrame.o src\view\ParentGUIFrame.o src\view\ClientGUIFrame.o src\model\TowerData.o src\controller\SimulationController.o src\THEIACyclonTechTower.o ..\Resource\resource.o -Lc:\wxWidgets-2.6.4\lib -Lc:\MinGW\lib\gcc-lib\i686-pc-mingw32\4.1.2 -Bdynamic -Wl,--subsystem,windows -mwindows c:\wxWidgets-2.6.4\lib\libwx_mswu-2.6.a -lwxregexu-2.6 -lwxexpat-2.6 -lwxtiff-2.6 -lwxjpeg-2.6 -lwxpng-2.6 -lwxzlib-2.6 -lrpcrt4 -loleaut32 -lole32 -luuid -lwinspool -lwinmm -lshell32 -lcomctl32 -lcomdlg32 -lctl3d32 -ladvapi32 -lwsock32 -lgdi32 -lgcc -lf95 c:\MinGW\lib\gcc-lib\i686-pc-mingw32\4.1.2/libf95.a(main.o):(.text+0x32): undefined reference to `MAIN_' collect2: ld returned 1 exit status Build error occurred, build is stopped Time consumed: 1531 ms. I have already read the g95 Manual for integration with C++ and I'm actually calling these functions bellow for controlling the fortran environment: void g95_runtime_start(int argc, char *argv[]); void g95_runtime_stop(); I also included the g95 Fortran Runtime Library libf95.a and the libgcc.a into my linker command. Finishing, I don't have a main method implemented because this is managed by wxWidgets, and my fortran subroutines can not have a main function because this is a C++ program calling fortran functions. Can some of you guys help me with this problem? How can I fix this undefined reference to MAIN__ problem? Any idea will be much appreciated. Thanks in advance, George

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  • How to calculate the height of a MultiCell/writeHTMLCell in TCPDF?

    - by merkuro
    I try to create a PDF with multiple pages and need to calculate the height of each individual element (MultiCell) in advance to prepare for a page break. According to the documentation there are a couple of functions out there like GetCharWidth/GetStringWidth to support me in doing it on my own, but besides a potential performance lost I probably will not do it the right anyway. Suggestions to achieve my goal in a more elegant way? Reference: TCPDF

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  • Get process id of process started with CreateObject in .NET

    - by Lex
    Hi! I'm using VB.NET for a web-application that starts some process using CreateObject, like this: Dim AVObject = CreateObject("avwin.application") After all is done everything get closed down en stopped using the proper release functions, however, for some reason the process remains. Is there some way in which I can get the process id of the started process, in order to explicitly kill it just before termination? Thanks

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  • Getting information of a class structure at runtime using Java reflection

    - by Eliza Sahoo
    A simple way to get the class structure information of the Class we are using in our application. Step1: Create the Class object of the class we want to explore at run time or the class which is getting added at runtime. Step2: As we are looking for the structure of the class, get all Constructors, Fields and methods by invoking respective functions of the Class. Step3: print them in java console or use them as required. Eliza

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  • What is in your Mathematica tool bag?

    - by Timo
    We all know that Mathematica is great, but it also often lacks critical functionality. What kind of external packages / tools / resources do you use with Mathematica? I'll edit (and invite anyone else to do so too) this main post to include resources which are focused on general applicability in scientific research and which as many people as possible will find useful. Feel free to contribute anything, even small code snippets (as I did below for a timing routine). Also, undocumented and useful features in Mathematica 7 and beyond you found yourself, or dug up from some paper/site are most welcome. Please include a short description or comment on why something is great or what utility it provides. If you link to books on Amazon with affiliate links please mention it, e.g., by putting your name after the link. Packages: LevelScheme is a package that greatly expands Mathematica's capability to produce good looking plots. I use it if not for anything else then for the much, much improved control over frame/axes ticks. David Park's Presentation Package ($50 - no charge for updates) Tools: MASH is Daniel Reeves's excellent perl script essentially providing scripting support for Mathematica 7. (This is finally built in as of Mathematica 8 with the -script option.) Resources: Wolfram's own repository MathSource has a lot of useful if narrow notebooks for various applications. Also check out the other sections such as Current Documentation, Courseware for lectures, and Demos for, well, demos. Books: Mathematica programming: an advanced introduction by Leonid Shifrin (web, pdf) is a must read if you want to do anything more than For loops in Mathematica. Quantum Methods with Mathematica by James F. Feagin (amazon) The Mathematica Book by Stephen Wolfram (amazon) (web) Schaum's Outline (amazon) Mathematica in Action by Stan Wagon (amazon) - 600 pages of neat examples and goes up to Mathematica version 7. Visualization techniques are especially good, you can see some of them on the author's Demonstrations Page. Mathematica Programming Fundamentals by Richard Gaylord (pdf) - A good concise introduction to most of what you need to know about Mathematica programming. Undocumented (or scarcely documented) Features: How to customize Mathematica keyboard shortcuts. See this question. How to inspect patterns and functions used by Mathematica's own functions. See this answer How to achieve Consistent size for GraphPlots in Mathematica? See this question.

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  • insert multiple rows via a php array into mysql

    - by toofarsideways
    I'm passing a large dataset into a mysql table via php using insert commands and I'm wondering if its possible to insert approximately 1000 rows at a time via a query other than appending each value on the end of an mile long string and then executing it. I am using the codeigniter framework so its functions are also available to me.

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  • HighCharts : Adding Hyperlinks to the X-Axis of the chart

    - by learner
    I have been using HighCharts in my PHP website by migrating it from older charts and I am very impressed by the number of graph options and functions with this library. However I am not able provide hyperlinks to the values of the x-axis(or y-axis) in order to navigate to another URI. Code of Categories in this case xAxis: { categories: [ 'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec' ] }, Can anyone point me to an example or documentation on Highcharts if available. Thanks

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  • iPhone static libraries: How to hide instance variable

    - by Frenzy
    I'm creating a static library to share using the following guide: http://www.amateurinmotion.com/articles/2009/02/08/creating-a-static-library-for-iphone.html In one of the functions, I return a "SomeUIView" which is a subclass of UIView and is defined in the public header, however I don't want to expose the internal instance variable of SomeUIView in the public header. I've tried using categories for a private internal header file for SomeUIView, but I keep running into "Duplicate interface declaration for class 'SomeUIView'". Does anyone know how to do this? Thanks!

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  • Javascript file as an anonymous function

    - by Andrew Kou
    I have been reading a lot of Javascript lately and I have been noticing that the whole file is wrapped like the following in the .js files to be imported. (function() { ... code ... })() What is the reason for doing this rather than a simple set of constructor functions?

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  • Question About Example In Robert C Martin's _Clean Code_

    - by Jonah
    This is a question about the concept of a function doing only one thing. It won't make sense without some relevant passages for context, so I'll quote them here. They appear on pgs 37-38: To say this differently, we want to be able to read the program as though it were a set of TO paragraphs, each of which is describing the current level of abstraction and referencing subsequent TO paragraphs at the next level down. To include the setups and teardowns, we include setups, then we include the test page content, and then we include the teardowns. To include the setups, we include the suite setup if this is a suite, then we include the regular setup. It turns out to be very dif?cult for programmers to learn to follow this rule and write functions that stay at a single level of abstraction. But learning this trick is also very important. It is the key to keeping functions short and making sure they do “one thing.” Making the code read like a top-down set of TO paragraphs is an effective technique for keeping the abstraction level consistent. He then gives the following example of poor code: public Money calculatePay(Employee e) throws InvalidEmployeeType { switch (e.type) { case COMMISSIONED: return calculateCommissionedPay(e); case HOURLY: return calculateHourlyPay(e); case SALARIED: return calculateSalariedPay(e); default: throw new InvalidEmployeeType(e.type); } } and explains the problems with it as follows: There are several problems with this function. First, it’s large, and when new employee types are added, it will grow. Second, it very clearly does more than one thing. Third, it violates the Single Responsibility Principle7 (SRP) because there is more than one reason for it to change. Fourth, it violates the Open Closed Principle8 (OCP) because it must change whenever new types are added. Now my questions. To begin, it's clear to me how it violates the OCP, and it's clear to me that this alone makes it poor design. However, I am trying to understand each principle, and it's not clear to me how SRP applies. Specifically, the only reason I can imagine for this method to change is the addition of new employee types. There is only one "axis of change." If details of the calculation needed to change, this would only affect the submethods like "calculateHourlyPay()" Also, while in one sense it is obviously doing 3 things, those three things are all at the same level of abstraction, and can all be put into a TO paragraph no different from the example one: TO calculate pay for an employee, we calculate commissioned pay if the employee is commissioned, hourly pay if he is hourly, etc. So aside from its violation of the OCP, this code seems to conform to Martin's other requirements of clean code, even though he's arguing it does not. Can someone please explain what I am missing? Thanks.

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  • Getting the index of the returned max or min item using max()/min() on a list

    - by KevinGriffin
    I'm using Python's max and min functions on lists for a minimax algorithm, and I need the index of the value returned by max() or min(). In other words, I need to know which move produced the max (at a first player's turn) or min (second player) value. for i in range(9): newBoard = currentBoard.newBoardWithMove([i / 3, i % 3], player) if newBoard: temp = minMax(newBoard, depth + 1, not isMinLevel) values.append(temp) if isMinLevel: return min(values) else: return max(values) I need to be able to return the actual index of the min or max value, not just the value.

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  • Offloading to HLSL/GPU without displaying?

    - by George R
    As far as I know, certain mathematical functions like FFTs and perlin noise, etc. can be much faster when done on the GPU as a pixel shader. My question is, if I wanted to exploit this to calculate results and stream to bitmaps, could I do it without needing to actually display it in Silverlight or something? More specifically, I was thinking of using this for large terrain generation involving lots of perlin and other noises, and post-processing like high passes and deriving normals from heightmaps, etc, etc.

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