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• How to find minimum of nonlinear, multivariate function using Newton's method (code not linear algeb

  - by Norman Ramsey

  I'm trying to do some parameter estimation and want to choose parameter estimates that minimize the square error in a predicted equation over about 30 variables. If the equation were linear, I would just compute the 30 partial derivatives, set them all to zero, and use a linear-equation solver. But unfortunately the equation is nonlinear and so are its derivatives. If the equation were over a single variable, I would just use Newton's method (also known as Newton-Raphson). The Web is rich in examples and code to implement Newton's method for functions of a single variable. Given that I have about 30 variables, how can I program a numeric solution to this problem using Newton's method? I have the equation in closed form and can compute the first and second derivatives, but I don't know quite how to proceed from there. I have found a large number of treatments on the web, but they quickly get into heavy matrix notation. I've found something moderately helpful on Wikipedia, but I'm having trouble translating it into code. Where I'm worried about breaking down is in the matrix algebra and matrix inversions. I can invert a matrix with a linear-equation solver but I'm worried about getting the right rows and columns, avoiding transposition errors, and so on. To be quite concrete: I want to work with tables mapping variables to their values. I can write a function of such a table that returns the square error given such a table as argument. I can also create functions that return a partial derivative with respect to any given variable. I have a reasonable starting estimate for the values in the table, so I'm not worried about convergence. I'm not sure how to write the loop that uses an estimate (table of value for each variable), the function, and a table of partial-derivative functions to produce a new estimate. That last is what I'd like help with. Any direct help or pointers to good sources will be warmly appreciated. Edit: Since I have the first and second derivatives in closed form, I would like to take advantage of them and avoid more slowly converging methods like simplex searches.

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• "Phased" execution of functions in javascript

  - by FK82

  Hey there! This is my first post on stackoverflow, so please don't flame me too hard if I come across like a total nitwit or if I'm unable ot make myself perfectly clear. :-) Here's my problem: I'm trying to write a javascript function that "ties" two functions to another by checking the first one's completion and then executing the second one. The easy solution to this obviously would be to write a meta function that calls both functions within it's scope. However, if the first function is asynchronous (specifically an AJAX call) and the second function requires the first one's result data, that simply won't work. My idea for a solution was to give the first function a "flag", i.e. making it create a public property "this.trigger" (initialized as "0", set to "1" upon completion) once it is called; doing that should make it possible for another function to check the flag for its value ([0,1]). If the condition is met ("trigger == 1") the second function should get called. The following is an abstract example code that I have used for testing: <script type="text/javascript" > /**/function cllFnc(tgt) { //!! first function this.trigger = 0 ; var trigger = this.trigger ; var _tgt = document.getElementById(tgt) ; //!! changes the color of the target div to signalize the function's execution _tgt.style.background = '#66f' ; alert('Calling! ...') ; setTimeout(function() { //!! in place of an AJAX call, duration 5000ms trigger = 1 ; },5000) ; } /**/function rcvFnc(tgt) { //!! second function that should get called upon the first function's completion var _tgt = document.getElementById(tgt) ; //!! changes color of the target div to signalize the function's execution _tgt.style.background = '#f63' ; alert('... Someone picked up!') ; } /**/function callCheck(obj) { //alert(obj.trigger ) ; //!! correctly returns initial "0" if(obj.trigger == 1) { //!! here's the problem: trigger never receives change from function on success and thus function two never fires alert('trigger is one') ; return true ; } else if(obj.trigger == 0) { return false ; } } /**/function tieExc(fncA,fncB,prms) { if(fncA == 'cllFnc') { var objA = new cllFnc(prms) ; alert(typeof objA + '\n' + objA.trigger) ; //!! returns expected values "object" and "0" } //room for more case definitions var myItv = window.setInterval(function() { document.getElementById(prms).innerHTML = new Date() ; //!! displays date in target div to signalize the interval increments var myCallCheck = new callCheck(objA) ; if( myCallCheck == true ) { if(fncB == 'rcvFnc') { var objB = new rcvFnc(prms) ; } //room for more case definitions window.clearInterval(myItv) ; } else if( myCallCheck == false ) { return ; } },500) ; } </script> The HTML part for testing: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/strict.dtd > <html> <head> <script type="text/javascript" > <!-- see above --> </script> <title> Test page </title> </head> <body> <!-- !! testing area --> <div id='target' style='float:left ; height:6em ; width:8em ; padding:0.1em 0 0 0; font-size:5em ; text-align:center ; font-weight:bold ; color:#eee ; background:#fff;border:0.1em solid #555 ; -webkit-border-radius:0.5em ;' > Test Div </div> <div style="float:left;" > <input type="button" value="tie calls" onmousedown="tieExc('cllFnc','rcvFnc','target') ;" /> </div> <body> </html> I'm pretty sure that this is some issue with javascript scope as I have checked whether the trigger gets set to "1" correctly and it does. Very likely the "checkCall()" function does not receive the updated object but instead only checks its old instance which obviously never flags completion by setting "this.trigger" to "1". If so I don't know how to address that issue. Anyway, hope someone has an idea or experience with this particular kind of problem. Thanks for reading! FK

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• How to keep my functions (objects/methods) 'lean and mean'

  - by Michel

  Hi, in all (Agile) articles i read about this: keep your code and functions small and easy to test. How should i do this with the 'controller' or 'coordinator' class? In my situation, i have to import data. In the end i have one object who coordinates this, and i was wondering if there is a way of keeping the coordinator lean(er) and mean(er). My coordinator now does the followling (pseudocode) //Write to the log that the import has started Log.StartImport() //Get the data in Excel sheet format result = new Downloader().GetExcelFile() //Log this step Log.LogStep(result ) //convert the data to intern objects result = new Converter().Convertdata(result); //Log this step Log.LogStep(result ) //write the data result = Repository.SaveData(result); //Log this step Log.LogStep(result ) Imho, this is one of those 'know all' classes or at least one being 'not lean and mean'? Or, am i taking this lean and mean thing to far and is it impossible to program an import without some kind of 'fat' importer/coordinator? Michel

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• Helper Casting Functions -- Is it a code smell?

  - by Earlz

  I recently began to start using functions to make casting easier on my fingers for one instance I had something like this ((Dictionary<string,string>)value).Add(foo); and converted it to a tiny little helper function so I can do this ToDictionary(value).Add(foo); Is this a code smell? Also, what about simpler examples? For example in my scripting engine I've considered making things like this ((StringVariable)arg).Value="foo"; be ToStringVar(arg).Value="foo"; I really just dislike how inorder to cast a value and instantly get a property from it you must enclose it in double parentheses. I have a feeling the last one is much worse than the first one though (also I've marked this language agnostic even though my example is C#)

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• Trying to debug a symfony app showing the list of all the functions called, debug_backtrace() doesn'

  - by user248959

  Hi, im trying to debug a symfony app. I've added a debug_backtrace() calling to this function below. It outputs a list of functions called, but the save() function (that is just before the debug_backtrace() calling) is not that list.. why? any other way to debug that shows more things, in this case the save() calling ? protected function processForm(sfWebRequest $request, sfForm $form) { $form->bind($request->getParameter($form->getName())); if ($form->isValid()) { $sf_guard_user = $form->save(); var_dump(debug_backtrace()); die("fsdgsgsdf"); $this->redirect('guardausuario/edit?id='.$sf_guard_user- >getId()); } } Regards Javi

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• Strange crashes on the iPad device with core graphics functions

  - by toastie

  I am getting a lot of strange EXC_BAD_ACCESS crashes on the iPad that only happen on the device and not in the simulator. I am assuming that they are somehow memory related, but I am not sure. They all happen with image context related functions. One strange example is using CGImageCreateWithImageInRect. For example, if i run through a bunch of UIImages and crop them with CGImageCreateWithImageInRect, it will always crash at specific arbitrary sizes. Like, if I crop them all to 200x200, it crashes out after processing 12 images. If i crop them to 210x210, it works no problem. The EXC_BAD_ACCESS happens inside of "memmove" called from "CGBlt_copyBytes". That is all the debugger shows me strangely enough. I can't see the callstack going up to any of my methods. All of this works fine in the simulator! I know this is all very vague, but if anyone has any ideas, they would be greatly appreciated.

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• wordpress functions.php

  - by Ayrton

  Hi I'm having issues with the functions.php file with variables $prev_dept = 0; $comment_count = 0; $comment_index = 0; function setCommentCount($size){ $comment_count = $size; } function flowhub_comment($comment, $args, $depth) { $comment_index ++; if($depth > 1) { $line = true; } echo '$prev_dept:' . $prev_dept.'<br>'; } I can't access $comment_index so I can't set nor get it from within a function. What should I do to fix this? Yours truthfully

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• Functions as pointers in Objective-C

  - by richman0829

  This is a question from Learn Objective-C on the Mac... Functions as pointers What I typed in, as per the recipe, was: NSString *boolString (BOOL yesNo) { if (yesNo) { return (@"YES"); } else { return (@"NO"); } } // boolString The pointer asterisk in the first line doesn't seem necessary, yet deleting it results in an error message. But what does it do? In NSString * boolString (yesNo); what seems to be going on is a function is defined as a pointer to an NSString. The function without the asterisk NSLog (@"are %d and %d different? %@", 5, 5, boolString(areTheyDifferent)); returns an NSString of YES or NO. But how can it return an NSString when it's a pointer? It might return the ADDRESS of an NSString; or if dereferenced it could return the CONTENTS of that address (an NSString such as YES or NO). Yet I see no place where it is dereferenced.

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• Dissapearing object function??

  - by WmasterJ

  Is there a reason for object functions to be unset or deleted or simply not applied for any reason at all that isn't intentional? I am maintaining someone elses code and gone through it many times. I use Google Chromes awesome debuger and also TextMate. These help me find the origin of error relatively fast. The problem I have now is that i have an object: types. This object conatains...types. And these types have functions and other variables attached to them. For some reason in the middle of the code, this type has been passed by reference millions of times probably. When it comes to a certain part of the code parts of it, seem to have dissapeared. Puff! And it's gone..! Anyone have a clue (other than it being removed somewhere else earlier in the code, I'm already looking for that)

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• executing two functions with wshshell

  - by sushant

  i have two different functions (copy and zip) to b executed. can i do it with with a single wshshell script.i tried---- Dim WshShell, oExec,g,h h="D:\d" g="xcopy " & h & " " & "D:\y\ /E & cmd /c cd D:\c & D: & winzip32.exe -min -a D:\a" Set WshShell = CreateObject("WScript.Shell") Set oExec = WshShell.Exec(g) Do While oExec.Status = 0 WScript.Sleep 100 Loop WScript.Echo oExec.Status it dint work.though separate programs i.e g="xcopy " & h & " " & "D:\y\ /E" and g="cmd /c cd D:\d & D: & winzip32.exe -min -a D:\a" works. i am sorry for the formatting problem. any help is appreciated.

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• exceptions with python unicode encode/decode functions (why doesn't errors=ignore actually ignore th

  - by gatoatigrado

  Does anyone know why the string conversion functions throw exceptions when errors="ignore" is passed? How can I convert from regular Python string objects to unicode without errors being thrown? Thanks very much! python -c "import codecs; codecs.open('tmp', 'wb', encoding='utf8', errors='ignore').write('?????')" returns Traceback (most recent call last): File "", line 1, in File "/usr/lib/python2.6/codecs.py", line 686, in write return self.writer.write(data) File "/usr/lib/python2.6/codecs.py", line 351, in write data, consumed = self.encode(object, self.errors) UnicodeDecodeError: 'ascii' codec can't decode byte 0xd0 in position 0: ordinal not in range(128)

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• To see javascript object properties and functions with intellisense in VS.NET 2008

  - by uzay95

  I am creating classes in external files.And adding them with <script src='../js/clsClassName.js' type='text/javascript'></script> tags. When i created an object from this class I can't access its props, and functions with intellisense. Is there any way to achieve this? Sample javascript class: // clsClassName.js function ClassName(_param1, _param2, _param3) { this.Prop1 = _param1; this.Prop1 = _param2; this.Prop3 = _param3; } ClassName.prototype.f_Add = function(fBefore, fSuccess, fComplete, fError) { } ClassName.prototype.f_Delete = function(fBefore, fSuccess, fComplete, fError) { } Any help would be greatly appreciated...

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• DisplayObject.rotation not matching trig functions

  - by futuraprime

  I'm trying to label an animated pie chart, and I've been having a great deal of trouble getting rotated objects to line up with trigonometrically-positioned objects. So, for example, if I have a pie piece that's middle is angle theta and has been rotated n degrees in a tween, and then I try to position a label with code like this: label.x = center.x + Math.cos((theta + n)/180 * Math.PI) * radius; label.y = center.y + Math.sin((theta + n)/180 * Math.PI) * radius; the label is often not aligned with the center of the pie slice. Since I am also zooming in to the pie chart a great deal, the error becomes significant enough that it occasionally causes the label to miss the pie slice altogether. The error seems relatively unpredictable, and it looks a great deal like a rounding error, but I don't see any obvious rounding going on (the trig functions evaluate to ten or so decimal places, which should be more than enough here). How can I get these labels to position correctly?

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• jquery plugin with multiple functions

  - by tcurdt

  According to the developer documentation jquery plugins are supposed to have only one namespace for all functions they make available. Which is straight forward as long as you only expose a single function per context (static/element). (function($){ var state_a = 0, $.myplugin = function(in_options) { // static return this; } $.fn.myplugin = function(in_options) { // element return this; } })(jQuery); This makes calls like this possible: $("elem").myplugin(options); jQuery.myplugin(options); What's the best approach if you have more than one function and need to share state? I would like to call into my plugin like this: $("elem").myplugin.start(options); $("elem").myplugin.stop(); jQuery.myplugin.start(options); jQuery.myplugin.stop();

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• Using clojure.contrib functions in slime REPL

  - by Tyler

  I want to use the functions in the clojure.contrib.trace namespace in slime at the REPL. How can I get slime to load them automatically? A related question, how can I add a specific namespace into a running repl? On the clojure.contrib API it describes usage like this: (ns my-namespace (:require clojure.contrib.trace)) But adding this to my code results in the file being unable to load with an "Unable to resolve symbol" error for any function from the trace package. I use leiningen 'lein swank' to start the ServerSocket and the project.clj file looks like this (defproject test-project "0.1.0" :description "Connect 4 Agent written in Clojure" :dependencies [[org.clojure/clojure "1.2.0-master-SNAPSHOT"] [org.clojure/clojure-contrib "1.2.0-SNAPSHOT"]] :dev-dependencies [[leiningen/lein-swank "1.2.0-SNAPSHOT"] [swank-clojure "1.2.0"]]) Everything seems up to date, i.e. 'lein deps' doesn't produce any changes. So what's up?

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• Are these two functions overkill for sanitization?

  - by jpjp

  function sanitizeString($var) { $var = stripslashes($var); $var = htmlentities($var); $var = strip_tags($var); return $var; } function sanitizeMySQL($var) { $var = mysql_real_escape_string($var); $var = sanitizeString($var); return $var; } I got these two functions from a book and the author says that by using these two, I can be extra safe against XSS(the first function) and sql injections(2nd func). Are all those necessary? Also for sanitizing, I use prepared statements to prevent sql injections. I would use it like this: $variable = sanitizeString($_POST['user_input']); $variable = sanitizeMySQL($_POST['user_input']);

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• -sizeWithFont Functions Differently on Device

  - by LucasTizma

  So I am seemingly encountering some strange behavior when using NSString's -sizeWithFont family of method calls depending on whether or not I'm invoking it on the iPhone Simulator or an actual device. Simply enough, when the receiver of the -sizeWithFont method call is nil, the resulting CGSize passed back on the Simulator is {0, 0}. However, on the device, it is the size of the bounding rectangle I specified in the method call. See the following log statements: Simulator: someString: (null) someStringSize: {0, 0} Device: someString: (null) someStringSize: {185, 3.40282e+38} The behavior on the Simulator is what I would expect. Not that this issue is difficult to circumvent, but 1) I'm a little confused why this family of functions would behave differently on the Simulator and an actual device, and 2) why does calling a method on a nil receiving return a particular result? Thanks for any pointers or insight you guys can provide! EDIT: I suppose I should mention that I'm building against the 3.1 SDK.

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• Make object available within php functions without passing them or making them global

  - by Matt

  Hey all, This requirement is just for simplicity for developers and beautiful code. I'm building a template system and I really would just like an object variable to simply be there in all functions. Here's some code: Librarian.php: $class = "slideshow"; $function = "basic"; $args = array(...); $librarian = $this; // I WOULD LIKE THIS TO BE PRESENT IN CALLED FUNCTION ... return call_user_func($class.'::'.$function, $args); ... Slideshow.php: public static function basic($args) { echo $librarian; // "Librarian Object" } Thanks! Matt Mueller

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• To see javascript object properties and functions with intellisense in VS.NET

  - by uzay95

  I am creating classes in external files.And adding them with <script src='../js/clsClassName.js' type='text/javascript'></script> tags. When i created an object from this class I can't access its props, and functions with intellisense. Is there any way to achieve this? // clsClassName.js function ClassName(_param1, _param2, _param3) { this.Prop1 = _param1; this.Prop1 = _param2; this.Prop3 = _param3; } ClassName.prototype.f_Add = function(fBefore, fSuccess, fComplete, fError) { } ClassName.prototype.f_Delete = function(fBefore, fSuccess, fComplete, fError) { } Any help would be greatly appreciated...

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• PhoneGap's vibrate() and beep() functions break in iPhone, Android emulators

  - by Steve Nay

  I have a PhoneGap app that I'm testing on webOS, Android, and iPhone. I'm using physical devices as well as emulators (the ones that come with their respective SDKs, not the PhoneGap emulator). Part of the code uses the navigator.notification.vibrate() and navigator.notification.beep() functions. All the physical devices I'm using either perform the behavior or ignore it if they're not capable (e.g., the iPod can't vibrate). However, the emulators behave differently. The Android emulator kills the app whenever the beep() function is called. The iPhone emulator causes the app to hang whenever the vibrate() function is called. Is there any way to get the emulators to ignore those function calls when they are unable to execute them? That is, is there a way to get them to degrade gracefully so I can test the app both places without having to modify the code specifically for the emulators?

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• tchar safe functions -- count parameter for UTF-8 constants

  - by Dustin Getz

  I'm porting a library from char to TCHAR. the count parameter of this fragment, according to MSDN, is the number of multibyte characters, not the number of bytes. so, did I get this right? _tcsncmp(access, TEXT("ftp"), 3); //or do i want _tcsnccmp? "Supported on Windows platforms only, _mbsncmp and _mbsnbcmp are multibyte versions of strncmp. _mbsncmp will compare at most count multibyte characters and _mbsnbcmp will compare at most count bytes. They both use the current multibyte code page. _tcsnccmp and _tcsncmp are the corresponding Generic functions for _mbsncmp and _mbsnbcmp, respectively. _tccmp is equivalent to _tcsnccmp."

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• Unit Testing functions within repository interfaces - ASP.net MVC3 & Moq

  - by RawryLions

  I'm getting into writing unit testing and have implemented a nice repository pattern/moq to allow me to test my functions without using "real" data. So far so good.. However.. In my repository interface for "Posts" IPostRepository I have a function: Post getPostByID(int id); I want to be able to test this from my Test class but cannot work out how. So far I am using this pattern for my tests: [SetUp] public void Setup() { mock = new Mock<IPostRepository>(); } [Test] public void someTest() { populate(10); //This populates the mock with 10 fake entries //do test here } In my function "someTest" I want to be able to call/test the function GetPostById. I can find the function with mock.object.getpostbyid but the "object" is null. Any help would be appreciated :) iPostRepository: public interface IPostRepository { IQueryable<Post> Posts {get;} void SavePost(Post post); Post getPostByID(int id); }

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• where to store helper functions?

  - by ajsie

  i've got a lot of functions i create or copy from the web. i wonder if i should store them in a file that i just include into the script or should i store each function as a static method in a class. eg. i've got a getCurrentFolder() and a isFilePhp() function. should they be stored in a file as they are or each in a class: Folder::getCurrent() File::isPhp(); how do you do? i know this is kinda a "as u want" question but it would be great with some advices/best practices thanks.

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• Renaming Functions during runtime in PHP.

  - by The Rook

  In PHP 5.3 is there a way to rename a function or "hook" a function. There is the rename_function() within "APD" which has been broken since ~2004. If you try and build it on PHP 5.3 you'll get this error: 'struct _zend_compiler_globals' has no member named 'extended_info' This is a really easy error to fix, just change this line: GC(extended_info) = 1; to CG(compiler_options) |= ZEND_COMPILE_EXTENDED_INFO; I modified my php.ini and the APD shows up in my phpinfo() as it should. However when i call rename_function() the PHP page doesn't load and I get a segmentation fault in my /var/log/apache2/error.log. Is there anyway to fix APD to work with a modern version of PHP? Or is there another method to rename functions? Why on earth is vital feature not in php!??!?! (Gotta love python :)

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• A PHP regex to extract php functions from code files

  - by user298593

  I'm trying to make a PHP regex to extract functions from php source code. Until now i used a recursive regex to extract everything between {} but then it also matches stuff like if statements. When i use something like: preg_match_all("/(function .(.))({([^{}]+|(?R))*})/",$this-data,$matches2); It doesn't work when there is more than 1 function in the file (probably because it uses the 'function' part in the recursiveness too). Is there any way to do this? Example file: <?php if($useless) { echo "i don't want this"; } function bla($wut) { echo "i do want this"; } ?> Thanks

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