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  • Min/Max across an array of objects

    - by graham.reeds
    It has been done to death pretty much, here on SO and around the 'Net. However I was wondering if there was a way to leverage the standard min/max functions of: Array.max = function(array) { return Math.max.apply(Math, array); }; Array.min = function(array) { return Math.min.apply(Math, array); }; So I can search across an array of objects of say: function Vector(x, y, z) { this.x = x; this.y = y; this.z = z; } var ArrayVector = [ /* lots of data */ ]; var min_x = ArrayVector.x.min(); // or var max_y = ArrayVector["y"].max(); Currently I have to loop through the array and compare the object values manually and craft each one to the particular need of the loop. A more general purpose way would be nice (if slightly slower).

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  • How can I return default at loop end in Scheme?

    - by Kufi Annan
    I'm trying to implement back-tracking search in Scheme. So far, I have the following: (define (backtrack n graph assignment) (cond (assignment-complete n assignment) (assignment) ) (define u (select-u graph assignment)) (define c 1) (define result 0) (let forLoop () (when (valid-choice graph assignment c) (hash-set! assignment u c) (set! result (backtrack n graph assignment)) (cond ((not (eq? result #f)) result)) (hash-remove! assignment u) ) (set! c (+ c 1)) (when (>= n c) (forLoop)) ) #f ) My functions assignment-complete and select-u pass unit tests. The argument assignment is a hash-table make with (make-hash), so it should be fine. I believe the problem I have is related to returning false at the end of the loop, if no recursive returns a non-false value (which should be a valid assignment).

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  • compare previous ENCRYPT() call with new ENCRYPT() call mysql

    - by contagious
    I'm storing a string in mysql with the ENCRYPT() function. I want to fetch a row where that string is matched, but the new ENCRYPT() call gives me a different value, so they never match. This is expected as i'm not (and can't) give it a consistent salt: http://dev.mysql.com/doc/refman/5.0/en/encryption-functions.html#function_encrypt If no salt argument is given, a random value is used. This is the query i'm running that returns empty: SELECT * FROM `table` WHERE ENCRYPT('string') = `enc_string` I know this is possible because this is used by a 3rd party app, but I can't find their query where they do this. Is there a way to force ENCRYPT to use the previous salt, or predict it?

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  • Codeigniter + Dwoo

    - by RedTruck
    I got problem when implementing my CMS using Codeigniter 1.7.2 and Dwoo. I use Phil Sturgeon Dwoo library. My problem is I want user create template from the admin panel, it means all template will be stored into database including all Dwoo variable and functions.My questions: Is it possible to load dwoo template from database? How to parse dwoo variable or function from database? I tried to load content from database which is include dwoo var and function inside it, and i have tried to do evaluation using dwoo eval() function and phil sturgeon string_parse() but still have no luck. for example: my controller $data['header'] = "<h1>{$header}</h1>"; --> this could be loaded from database $this->parser->parse('header',$data); my view {$header} Thank you,

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  • How to create a asp.net membership provider hashed password manually?

    - by Anheledir
    I'm using a website as a frontend and all users are authenticated with the standard ASP.NET Membership-Provider. Passwords are saved "hashed" within a SQL-Database. Now I want to write a desktop-client with administrative functions. Among other things there should be a method to reset a users password. I can access the database with the saved membership-data, but how can I manually create the password-salt and -hash? Using the System.Web.Membership Namespace seems to be inappropriate so I need to know how to create the salt and hash of the new password manually. Experts step up! :)

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  • How to do a sample rate conversion in Windows (and OSX)

    - by Paperflyer
    I am about to write an audio file converter for my side job at the university. As part of this I would need sample rate conversion. However, my professor said that it would be pretty hard to write a sample rate converter that was both of good quality and fast. On my research on the subject, I found some functions in the OSX CoreAudio-framework, that could do a sample rate conversion (AudioConverter.h). After all, an OS has to have some facilities to do that for its own audio stack. Do you know a similar method for C/C++ and Windows, that are either part of the OS or open source? I am pretty sure that this function exists within DirectX Audio (XAudio2?), but I seem to be unable to find a reference to it in the MSDN library.

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  • Using sphinx to create context sensitive html help

    - by bluebill
    Hi all, I am currently using AsciiDoc (http://www.methods.co.nz/asciidoc/) for documenting my software projects because it supports pdf and html help generation. I am currently running it through cygwin so that the a2x tool chain functions properly. This works well for me but is a pain to setup on other windows computers. I have been looking for alternative methods and recently revisited Sphinx. Noticing that it now produces html help files I gave it a try and it seems to work well in the small tests I performed. My question is, is there a way to specify map id's for context sensitive help in the text so that my windows programs can call the proper help api and the file is launched and opened to the desired location? In AsciiDoc I am using "pass::[]". By using these constructs a context.h and alias.h are generated along with the other html help files (context sensitive help information).

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  • Getting memory section information

    - by Basilevs
    Can somebody explain me how the following code works? # if defined(__ELF__) # define __SECTION_FLAGS ", \"aw\" , @progbits" /* writable flag needed for ld ".[cd]tors" sections bug workaround) */ # elif defined(__COFF__) # define __SECTION_FLAGS ", \"dr\"" /* untested, may be writable flag needed */ # endif asm ( ".section .ctors" __SECTION_FLAGS "\n" ".globl __ctors_begin__\n" "__ctors_begin__:\n" ".previous\n" ); asm /* ld ".[cd]tors" sections bug workaround */ ( ".section .ctors0" __SECTION_FLAGS "\n" ".globl __ctors0_begin__\n" "__ctors0_begin__:\n" ".previous\n" ); Similarly we are getting __ctors_end__ , __ctors0_end__ and destructors location is also obtained this way. After some ld bug workarounds all functions pointed by pointers from __ctors_begin__ to __ctors_end__ are executed. I don't know assembler and this code is impossible for me to interpret. BTW: I know that invoking C++ contructors/destructors from C is not a task to be considered safe or easy.

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  • Math: How to sum each row of a matrix

    - by macek
    I have a 1x8 matrix of students where each student is a 4x1 matrix of scores. Something like: SCORES S [62, 91, 74, 14] T [59, 7 , 59, 21] U [44, 9 , 69, 6 ] D [4 , 32, 28, 53] E [78, 99, 53, 83] N [48, 86, 89, 60] T [56, 71, 15, 80] S [47, 67, 79, 40] Main question: Using sigma notation, or some other mathematical function, how can I get a 1x8 matrix where each student's scores are summed? # expected result TOTAL OF SCORES S [241] T [146] U [128] D [117] E [313] N [283] T [222] S [233] Sub question. To get the average, I will multiply the matrix by 1/4. Would there be a quicker way to get the final result? AVERAGE SCORE S [60.25] T [36.50] U [32.00] D [29.25] E [78.25] N [70.75] T [55.50] S [58.25] Note: I'm not looking for programming-related algorithms here. I want to know if it is possible to represent this with pure mathematical functions alone.

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  • Probability distribution for sms answer delays

    - by Thomas Ahle
    I'm writing an app using sms as communication. I have chosen to subscribe to an sms-gateway, which provides me with an API for doing so. The API has functions for sending as well as pulling new messages. It does however not have any kind of push functionality. In order to do my queries most efficient, I'm seeking data on how long time people wait before they answer a text message - as a probability function. Extra info: The application is interactive (as can be), so I suppose the times will be pretty similar to real life human-human communication. I don't believe differences in personal style will play a big impact on the right times and frequencies to query, so average data should be fine.

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  • Changing system colors for a single application (Windows, .NET)

    - by Michal Czardybon
    I know I should generally avoid messing up with such system settings, but my application do already use nonstandard colors and I have no influence on that. I would like to be able to add standard .NET controls in some places, but their colors do not match. I would like to have a hack that would replace system colors for this one application. One more important thing to note is that it is a .NET application. My (incomplete) ideas so far were: To create a proxy User32.dll library with replaced GetSysColor, but it would be very tedious (731 functions to be redirected, 1 to be replaced) and I do not know how to force my application to use that particular copy. To intercept somehow invocations to GetSysColors (unfortunatelly it is somewhere in the CLR I think). To modify somehow .NET class SystemColors (in memory? is it possible?). Do you have any idea, what is the best (and complete) way to achieve this?

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  • Can Stopwatch be used in production code?

    - by Adrian
    Hi, I need an accurate timer, and DateTime.Now seems not accurate enough. From the descriptions I read, System.Diagnostics.Stopwatch seems to be exactly what I want. But I have a phobia. I'm nervous about using anything from System.Diagnostics in actual production code. (I use it extensively for debugging with Asserts and PrintLns etc, but never yet for production stuff.) I'm not merely trying to use a timer to benchmark my functions - my app needs an actual timer. I've read on another forum that System.Diagnostics.StopWatch is only for benchmarking, and shouldn't be used in retail code, though there was no reason given. Is this correct, or am I (and whoever posted that advice) being too closed minded about System.Diagnostics? ie, is it ok to use System.Diagnostics.Stopwatch in production code? Thanks Adrian

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  • Compiling .NET component that uses a non specific required version of a 3rd Party Vendor component

    - by Dan
    If someone were to develop a .NET component that relied on non specific versions of a vendor DLL - let's say it worked with My3rdPartyComponent.dll which is a .NET assembly, but it didn't matter which version. Some instances of classes found in this component would need to be passed into my component. Developers would reference my component dll but not have access to the source code. Basically, I want to be able to require the user to pass in an instance of 3rdPartyComponent.MyClass to my component functions but I do not care if it's version 1.1, 2.2, 2.23.980, etc of the 3rd party dll. Is there a way to do this while still typing the parameter I want to be passed in to my component? I don't want to use Object as the reference. In my component project I could specify SpecificVersion=True on the assembly reference. Will this solve my problem or will there be other 'dll hell' issues to deal with that I am not seeing?

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  • C/C++ Allegro program causes Windows 7 to switch to Aero Basic

    - by Matt H
    Hi SO, I'm just trying out the allegro library, and here is the code which I've got so far: #include <allegro.h> int main(int argc, char *argv[]) { allegro_init(); // initialize the allegro libraries install_keyboard(); // initialize keyboard functions set_color_depth(16); // set the color depth set_gfx_mode(GFX_AUTODETECT_WINDOWED, 640, 480, 0, 0); // set up 640*480px window BITMAP *pic = NULL; pic = load_bitmap("C:/picture.bmp", NULL); // load the picture blit(pic, screen, 0, 0, 0, 0, 1000, 1000); readkey(); destroy_bitmap(pic); return 0; } END_OF_MAIN() It works fine, but when I run it, while the program's window is open, Windows 7 changes the theme from Aero to Aero basic. If you aren't sure what I mean, this pops up (I got this from Google, which is why it says Vista rather than Windows 7): 1) Why? 2) How can I ensure that this doesn't happen?

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  • The difference between traditional DLL and COM DLL.

    - by smwikipedia
    I am currently studying COM. I found that COM DLL is kind of built upon the traditional DLL infrastructure. When we build COM DLLs, we still rely on the traditional DLL export methods to lead us to the internal COM co-classes. If COM is for component reusing at the binary level, I think the traditional DLL can achieve the same thing. They both expose functions, they are both binary, so what's the point of turning to COM approach? Currently, I have the feeling that the traditional DLL expose methods in a "flat" manner, while the COM DLL expose methods in an "OOP" hierarchy manner. And the OOP manner seems to be a better approach. Could this be the reason why COM prevails? Many thanks.

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  • Does a version control database storage engine exist?

    - by Zak
    I was just wondering if a storage engine type existed that allowed you to do version control on row level contents. For instance, if I have a simple table with ID, name, value, and ID is the PK, I could see that row 354 started as (354, "zak", "test")v1 then was updated to be (354, "zak", "this is version 2 of the value")v2 , and could see a change history on the row with something like select history (value) where ID = 354. It's kind of an esoteric thing, but it would beat having to keep writing these separate history tables and functions every time a change is made...

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  • Creating Instance of a DataContract Class on the client side

    - by hgulyan
    I'm not sure, if it's right to do this, but I'd like to ask this question again ( http://stackoverflow.com/questions/2498644/creating-instance-of-a-service-side-datacontract-class-on-client-side-in-wcf ). The main question is - why there's difference between creating instance on the client side and creating it on the server side? Why there're some properties, that lose their values when you create them on the client side and pass it to service's functions? What could be the issue? Any version will be appreciated. I've written about my problem in the update part of the question in that link. Thank You. p.s. If this is against the rules, I'll delete it.

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  • Postcode and radius lookup recommendations

    - by WestDiscGolf
    I look after a number of divisional websites for a uk based membership organisation and what we want to do is provide, as well as other address functions, is a closest member lookup to a web user from the websites themselves. A few use cases that I want to fill: Case 1: The user puts in their post code and wants to see all the members in a 5/10/15/20/30/40 mile radius from them Case 2: The member puts in an area (city, county, etc.) and gets a list of members in that area. Essentially what I'm looking for is a programmable API which I can code against to do: post code lookup and returns addresses (after picking house number for example). search post code + radius (5miles, 10miles etc) and get a set of applicable post codes to then join onto the membership records in the database Any recommendations? It can be a quarterly update install on the server, it can be a queryable web service. I'm open to suggestions. Thanks in advance

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  • Screen Capture with Open GL using glReadPixels

    - by Raja
    Hi, I created a CGRegisterScreenRefreshCallback(refreshCallback, NULL) and in the refreshCallback method get the list of rectangles which have changed. I am getting the rectangle data from frameBuffer using OpenGL glReadPixels. Is there a better way of screen capture either with/without opengl and also using OpenGL can I skip reading pixel by pixel ? I have looked at glGetTexImage and glCopyTexSubImage2D. Any simple code block which can explain how to use these functions to get the changed rectangle data would be very helpful ? Thanks, Raja.

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  • Re-using jQuery widgets

    - by Micor
    I am looking for a most efficient way to re-use widgets with different selectors... For example if I have: $("#selector1").datepicker({ beforeShow: function(var1,var2) { // do stuff }, onClose: function(var1,var2) { // do stuff }, onSelect: function(var1,var2) { // do stuff } }) And later I am looking to assign this same widget with same functions inside to other selectors which are not known at load time. Since its not about choosing a better selector and I want to avoid: $("#new-selector2").datepicker({ beforeShow: function(var1,var2) { // do stuff }, onClose: function(var1,var2) { // do stuff }, onSelect: function(var1,var2) { // do stuff } }) $("#new-selector3").datepicker({ beforeShow: function(var1,var2) { // do stuff }, onClose: function(var1,var2) { // do stuff }, onSelect: function(var1,var2) { // do stuff } }) What would be the best way of doing something like: var reusableDatepicker = datepicker({ beforeShow: function(var1,var2) { // do stuff }, onClose: function(var1,var2) { // do stuff }, onSelect: function(var1,var2) { // do stuff } }) $("#selector1").attach(reusableDatepicker); $("#new-selector2").attach(reusableDatepicker); $("#new-selector3").attach(reusableDatepicker); I know it has to be obvious to all jQuery devs out there, so obvious I cannot find it in docs :) Thank you!

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  • Finding distance travelled by robot using Optical Flow

    - by user280454
    Hi, I'm working on a project right now in which we are developing an autonomous robot. I have to basically find out the distance travelled by the robot between any 2 intervals. I'm using OpenCV, and using the Optical Flow functions of OpenCV, I'm able to find out the velocity/distance of each pixel in 2 different images. Using this information, I want to be able to find out the distance travelled by the robot in the interval between those 2 images. I thought of a way in which we could develop an input output mapping between the distance travelled by pixels and the distance travelled by the bot (using some tests). In this way, using neural networks, we would be able to find the relationship. However, the optical flow would depend on the distance of the camera from the pixel, which would cause problems. Is there any way to solve this problem?

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  • How can I convert input to HTML Characters correctly

    - by Codex73
    Let's say I'm including a file which contains html. The html have characters as exclamation symbols, Spanish accents (á, ó). The parsed included text gets processed as symbols instead of their correct value. This happens on FF but not on IE (8). I have tried the following functions: htmlspecialchars, htmlentities, utf8_encode include htmlentities("cont/file.php"); Sample file.php contents: <div>Canción, “Song Name”</div> Output: Canci?n, ?Song Name?

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  • will a mysql query run slower if one of the tables involved has no index defined??

    - by lock
    there's this already populated database which came from another dev im not sure what went on that dev's mind when he created the tables, but on one of our scripts there is this query involving 4 tables and it runs super slow SELECT a.col_1, a.col_2, a.col_3, a.col_4, a.col_5, a.col_6, a.col_7 FROM a, b, c, d WHERE a.id = b.id AND b.c_id = c.id AND c.id = d.c_id AND a.col_8 = '$col_8' AND d.g_id = '$g_id' AND c.private = '1' NOTE: $col_8 and $g_id are variables from a form its only my theory that it's due to tables b and c not having an index, although im guessing that the dev didnt think that it was necessary since those tables only tell relations between a and d, where b tells that the data in a belongs to a certain user, and c tells that the user belongs to a group in d as you can see, there's not even a join or other extensive query functions used but this query which returns only around 100 rows takes 2 minutes to execute. anyway my question is simply this post's title. will a mysql query run slower if one of the tables involved has no index defined??

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  • Passing Boost uBLAS matrices to OpenGL shader

    - by AJM
    I'm writing an OpenGL program where I compute my own matrices and pass them to shaders. I want to use Boost's uBLAS library for the matrices, but I have little idea how to get a uBLAS matrix into OpenGL's shader uniform functions. matrix<GLfloat, column_major> projection(4, 4); // Fill matrix ... GLuint projectionU = glGetUniformLocation(shaderProgram, "projection"); glUniformMatrix4fv(projectionU, 1, 0, (GLfloat *)... Um ...); Trying to cast the matrix to a GLfloat pointer causes an invalid cast error on compile.

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  • How should I rewrite my code to make it amenable to unittesting?

    - by justin
    I've been trying to get started with unit-testing while working on a little cli program. My program basically parses the command line arguments and options, and decides which function to call. Each of the functions performs some operation on a database. So, for instance, I might have a create function: def create(self, opts, args): #I've left out the error handling. strtime = datetime.datetime.now().strftime("%D %H:%M") vals = (strtime, opts.message, opts.keywords, False) self.execute("insert into mytable values (?, ?, ?, ?)", vals) self.commit() Should my test case call this function, then execute the select sql to check that the row was entered? That sounds reasonable, but also makes the tests more difficult to maintain. Would you rewrite the function to return something and check for the return value? Thanks

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