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  • matlab constant anonymous function returns only one value instead of an array

    - by Filo
    I've been searching the net for a couple of mornings and found nothing, hope you can help. I have an anonymous function like this f = @(x,y) [sin(2*pi*x).*cos(2*pi*y), cos(2*pi*x).*sin(2*pi*y)]; that needs to be evaluated on an array of points, something like x = 0:0.1:1; y = 0:0.1:1; w = f(x',y'); Now, in the above example everything works fine, the result w is a 11x2 matrix with in each row the correct value f(x(i), y(i)). The problem comes when I change my function to have constant values: f = @(x,y) [0, 1]; Now, even with array inputs like before, I only get out a 1x2 array like w = [0,1]; while of course I want to have the same structure as before, i.e. a 11x2 matrix. I have no idea why Matlab is doing this...

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  • Oracle function always returning null

    - by JavaRocky
    I can't get this function to behave as i desire. Can anyone point out why it always returns null instead of CURRENT_TIMESTAMP? CREATE OR REPLACE FUNCTION nowts RETURN TIMESTAMP IS vTimestamp TIMESTAMP; BEGIN SELECT type_date INTO vTimestamp FROM param_table WHERE param_table = 3 AND exists ( SELECT * FROM param_table WHERE param_table = 2 ); IF vTimestamp IS NULL THEN vTimestamp := CURRENT_TIMESTAMP; END IF; return vTimestamp; END nowts; Right now there is nothing in the table named param_table.

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  • C++ function-pointer and inheritance

    - by pingvinus
    In parent class I have function, that operates under an array of functions, declared in child-class, number of functions for every child-class may vary. But since every function uses some object-variables, I can't declare them as static. I've try to do something like this: class A { public: typedef int (A::*func)(); func * fs; void f() { /*call functions from this->fs*/ } }; class B : public A { public: int smth; B(int smth) { this->smth = smth; this->fs = new func[1]; fs[0] = &B::f; } int f() { return smth + 1; } }; But, obviously it doesn't work. Any suggestions?

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  • PostgreSQL function to iterate through/act on many rows with state

    - by Claudiu
    I have a database with columns looking like: session | order | atype | amt --------+-------+-------+----- 1 | 0 | ADD | 10 1 | 1 | ADD | 20 1 | 2 | SET | 35 1 | 3 | ADD | 10 2 | 0 | SET | 30 2 | 1 | ADD | 20 2 | 2 | SET | 55 It represents actions happening. Each session starts at 0. ADD adds an amount, while SET sets it. I want a function to return the end value of a session, e.g. SELECT session_val(1); --returns 45 SELECT session_val(2); --returns 55 Is it possible to write such a function/query? I don't know how to do any iteration-like things with SQL, or if it's possible at all.

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  • Adding a method to a function object at runtime

    - by Carson Myers
    I read a question earlier asking if there was a times method in Python, that would allow a function to be called n times in a row. Everyone suggested for _ in range(n): foo() but I wanted to try and code a different solution using a function decorator. Here's what I have: def times(self, n, *args, **kwargs): for _ in range(n): self.__call__(*args, **kwargs) import new def repeatable(func): func.times = new.instancemethod(times, func, func.__class__) @repeatable def threeArgs(one, two, three): print one, two, three threeArgs.times(7, "one", two="rawr", three="foo") When I run the program, I get the following exception: Traceback (most recent call last): File "", line 244, in run_nodebug File "C:\py\repeatable.py", line 24, in threeArgs.times(7, "one", two="rawr", three="foo") AttributeError: 'NoneType' object has no attribute 'times' So I suppose the decorator didn't work? How can I fix this?

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  • get the list and input from one function and run them in different function

    - by rookie
    i have a programm that generate the list and then i ask them to tell me what they want to do from the menu and this is where my problem start i was able to get the input form the user to different function but when i try to use the if else condition it doesn't check, below are my code def menu(x,l): print (x) if x == 1: return make_table(l) if x == 2: y= input("enter a row (as a number) or a column (as an uppercase letter") if y in [ "1",'2','3']: print("Minmum is:",minimum(y,l)) if x== 3: print ('bye') def main(): bad_filename = True l =[] while bad_filename == True: try: filename = input("Enter the filename: ") fp = open(filename, "r") for f_line in fp: f_str=f_line.strip() f_str=f_str.split(',') for unit_str in f_str: unit=float(unit_str) l.append(unit) bad_filename = False except IOError: print("Error: The file was not found: ", filename) #print(l) condition=True while condition==True: print('1- open\n','2- maximum') x=input("Enter the choice") menu(x,l) main() from the bottom function i can get list and i can get the user input and i can get the data and move it in second function but it wont work after that.thank you

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  • How to get the entire code of a method in memory so I can calculate its hash at runtime?

    - by bejo
    Hello stackoverflow, How to get the entire code of a method in memory so I can calculate its hash at runtime? I need to make a function like this: type TProcedureOfObject = procedure of object; function TForm1.CalculateHashValue (AMethod: TProcedureOfObject): string; var MemStream: TMemoryStream; begin result:=''; MemStream:=TMemoryStream.Create; try //how to get the code of AMethod into TMemoryStream? result:=MD5(MemStream); //I already have the MD5 function finally MemStream.Free; end; end; I use Delphi 7. Thank you.

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  • Misunderstanding function pointer - passing it as an argument

    - by Stef
    I want to pass a member function of class A to class B via a function pointer as argument. Please advise whether this road is leading somewhere and help me fill the pothole. #include <iostream> using namespace std; class A{ public: int dosomeA(int x){ cout<< "doing some A to "<<x <<endl; return(0); } }; class B{ public: B(int (*ptr)(int)){ptr(0);}; }; int main() { A a; int (*APtr)(int)=&A::dosomeA; B b(APtr); return 0; } This brilliant piece of code leaves me with the compiler error: cannot convert int (A::*)(int)' toint (*)(int)' in initialization Firstly I want it to compile. Secondly I don't want dosomeA to be STATIC.

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  • Reading function pointer syntax

    - by bobobobo
    Everytime I look at a C function pointer, my eyes glaze over. I can't read them. From here, here are 2 examples of function pointer TYPEDEFS: typedef int (*AddFunc)(int,int); typedef void (*FunctionFunc)(); Now I'm used to something like: typedef vector<int> VectorOfInts ; Which I read as typedef vector<int> /* as */ VectorOfInts ; But I can't read the above 2 typedefs. The bracketing and the asterisk placement, it's just not logical. Why is the * beside the word AddFunc..?

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  • Get result type of function

    - by Robert
    I want to specialize a template function declared as: template<typename Type> Type read(std::istream& is); I then have a lot of static implementations static int read_integer(std::istream& is); a.s.o. Now I'd like to do a macro so that specialization of read is as simple as: SPECIALIZE_READ(read_integer) So I figured I'd go the boost::function_traits way and declare SPECIALIZE_READ as: #define SPECIALIZE_READ(read_function) \ template<> boost::function_traits<read_function>::result_type read(std::istream& is) { \ return read_function(is); \ } but VC++ (2008) compiler complains with: 'boost::function_traits' : 'read_integer' is not a valid template type argument for parameter 'Function' Ideas ?

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  • Object is not a function on call to dialog() function

    - by coffeeaddict
    I keep getting "dialogDiv.dialog is not a function". I'm simply trying to invoke the jQueryUI dialog off my reference to the div. So incoming is the divID, for example "myDiv". Then I set it to a variable and wrap it in $("#" + myDiv); so that now I have a reference to it in a nice clear variable. Then I try to invoke the dialog function and get that error. not sure why and it's driving me nuts. function showDialog(divID) { // Get reference to the div element var dialogDiv = $("#" + divID); alert("dialogDiv:" + dialogDiv); dialogDiv.dialog ( { bgiframe: true, modal: true, autoOpen: false, show: 'blind' } ) dialogDiv.dialog("open"); }

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  • Game Over function is not working Starling

    - by aNgeLyN omar
    I've been following a tutorial over the web but it somehow did not show something about creating a game over function. I am new to the Starling framework and Actionscript so I'm kind of still trying to find a way to make it work. Here's the complete snippet of the code. package screens { import flash.geom.Rectangle; import flash.utils.getTimer; import events.NavigationEvent; import objects.GameBackground; import objects.Hero; import objects.Item; import objects.Obstacle; import starling.display.Button; import starling.display.Image; import starling.display.Sprite; import starling.events.Event; import starling.events.Touch; import starling.events.TouchEvent; import starling.text.TextField; import starling.utils.deg2rad; public class InGame extends Sprite { private var screenInGame:InGame; private var screenWelcome:Welcome; private var startButton:Button; private var playAgain:Button; private var bg:GameBackground; private var hero:Hero; private var timePrevious:Number; private var timeCurrent:Number; private var elapsed:Number; private var gameState:String; private var playerSpeed:Number = 0; private var hitObstacle:Number = 0; private const MIN_SPEED:Number = 650; private var scoreDistance:int; private var obstacleGapCount:int; private var gameArea:Rectangle; private var touch:Touch; private var touchX:Number; private var touchY:Number; private var obstaclesToAnimate:Vector.<Obstacle>; private var itemsToAnimate:Vector.<Item>; private var scoreText:TextField; private var remainingLives:TextField; private var gameOverText:TextField; private var iconSmall:Image; static private var lives:Number = 2; public function InGame() { super(); this.addEventListener(starling.events.Event.ADDED_TO_STAGE, onAddedToStage); } private function onAddedToStage(event:Event):void { this.removeEventListener(Event.ADDED_TO_STAGE, onAddedToStage); drawGame(); scoreText = new TextField(300, 100, "Score: 0", "MyFontName", 35, 0xD9D919, true); remainingLives = new TextField(600, 100, "Lives: " + lives +" X ", "MyFontName", 35, 0xD9D919, true); iconSmall = new Image(Assets.getAtlas().getTexture("darnahead1")); iconSmall.x = 360; iconSmall.y = 40; this.addChild(iconSmall); this.addChild(scoreText); this.addChild(remainingLives); } private function drawGame():void { bg = new GameBackground(); this.addChild(bg); hero = new Hero(); hero.x = stage.stageHeight / 2; hero.y = stage.stageWidth / 2; this.addChild(hero); startButton = new Button(Assets.getAtlas().getTexture("startButton")); startButton.x = stage.stageWidth * 0.5 - startButton.width * 0.5; startButton.y = stage.stageHeight * 0.5 - startButton.height * 0.5; this.addChild(startButton); gameArea = new Rectangle(0, 100, stage.stageWidth, stage.stageHeight - 250); } public function disposeTemporarily():void { this.visible = false; } public function initialize():void { this.visible = true; this.addEventListener(Event.ENTER_FRAME, checkElapsed); hero.x = -stage.stageWidth; hero.y = stage.stageHeight * 0.5; gameState ="idle"; playerSpeed = 0; hitObstacle = 0; bg.speed = 0; scoreDistance = 0; obstacleGapCount = 0; obstaclesToAnimate = new Vector.<Obstacle>(); itemsToAnimate = new Vector.<Item>(); startButton.addEventListener(Event.TRIGGERED, onStartButtonClick); //var mainStage:InGame =InGame.current.nativeStage; //mainStage.dispatchEvent(new Event(Event.COMPLETE)); //playAgain.addEventListener(Event.TRIGGERED, onRetry); } private function onStartButtonClick(event:Event):void { startButton.visible = false; startButton.removeEventListener(Event.TRIGGERED, onStartButtonClick); launchHero(); } private function launchHero():void { this.addEventListener(TouchEvent.TOUCH, onTouch); this.addEventListener(Event.ENTER_FRAME, onGameTick); } private function onTouch(event:TouchEvent):void { touch = event.getTouch(stage); touchX = touch.globalX; touchY = touch.globalY; } private function onGameTick(event:Event):void { switch(gameState) { case "idle": if(hero.x < stage.stageWidth * 0.5 * 0.5) { hero.x += ((stage.stageWidth * 0.5 * 0.5 + 10) - hero.x) * 0.05; hero.y = stage.stageHeight * 0.5; playerSpeed += (MIN_SPEED - playerSpeed) * 0.05; bg.speed = playerSpeed * elapsed; } else { gameState = "flying"; } break; case "flying": if(hitObstacle <= 0) { hero.y -= (hero.y - touchY) * 0.1; if(-(hero.y - touchY) < 150 && -(hero.y - touchY) > -150) { hero.rotation = deg2rad(-(hero.y - touchY) * 0.2); } if(hero.y > gameArea.bottom - hero.height * 0.5) { hero.y = gameArea.bottom - hero.height * 0.5; hero.rotation = deg2rad(0); } if(hero.y < gameArea.top + hero.height * 0.5) { hero.y = gameArea.top + hero.height * 0.5; hero.rotation = deg2rad(0); } } else { hitObstacle-- cameraShake(); } playerSpeed -= (playerSpeed - MIN_SPEED) * 0.01; bg.speed = playerSpeed * elapsed; scoreDistance += (playerSpeed * elapsed) * 0.1; scoreText.text = "Score: " + scoreDistance; initObstacle(); animateObstacles(); createEggItems(); animateItems(); remainingLives.text = "Lives: "+lives + " X "; if(lives == 0) { gameState = "over"; } break; case "over": gameOver(); break; } } private function gameOver():void { gameOverText = new TextField(800, 400, "Hero WAS KILLED!!!", "MyFontName", 50, 0xD9D919, true); scoreText = new TextField(800, 600, "Score: "+scoreDistance, "MyFontName", 30, 0xFFFFFF, true); this.addChild(scoreText); this.addChild(gameOverText); playAgain = new Button(Assets.getAtlas().getTexture("button_tryAgain")); playAgain.x = stage.stageWidth * 0.5 - startButton.width * 0.5; playAgain.y = stage.stageHeight * 0.75 - startButton.height * 0.75; this.addChild(playAgain); playAgain.addEventListener(Event.TRIGGERED, onRetry); } private function onRetry(event:Event):void { playAgain.visible = false; gameOverText.visible = false; scoreText.visible = false; var btnClicked:Button = event.target as Button; if((btnClicked as Button) == playAgain) { this.dispatchEvent(new NavigationEvent(NavigationEvent.CHANGE_SCREEN, {id: "playnow"}, true)); } disposeTemporarily(); } private function animateItems():void { var itemToTrack:Item; for(var i:uint = 0; i < itemsToAnimate.length; i++) { itemToTrack = itemsToAnimate[i]; itemToTrack.x -= playerSpeed * elapsed; if(itemToTrack.bounds.intersects(hero.bounds)) { itemsToAnimate.splice(i, 1); this.removeChild(itemToTrack); } if(itemToTrack.x < -50) { itemsToAnimate.splice(i, 1); this.removeChild(itemToTrack); } } } private function createEggItems():void { if(Math.random() > 0.95){ var itemToTrack:Item = new Item(Math.ceil(Math.random() * 10)); itemToTrack.x = stage.stageWidth + 50; itemToTrack.y = int(Math.random() * (gameArea.bottom - gameArea.top)) + gameArea.top; this.addChild(itemToTrack); itemsToAnimate.push(itemToTrack); } } private function cameraShake():void { if(hitObstacle > 0) { this.x = Math.random() * hitObstacle; this.y = Math.random() * hitObstacle; } else if(x != 0) { this.x = 0; this.y = 0; lives--; } } private function initObstacle():void { if(obstacleGapCount < 1200) { obstacleGapCount += playerSpeed * elapsed; } else if(obstacleGapCount !=0) { obstacleGapCount = 0; createObstacle(Math.ceil(Math.random() * 5), Math.random() * 1000 + 1000); } } private function animateObstacles():void { var obstacleToTrack:Obstacle; for(var i:uint = 0; i<obstaclesToAnimate.length; i++) { obstacleToTrack = obstaclesToAnimate[i]; if(obstacleToTrack.alreadyHit == false && obstacleToTrack.bounds.intersects(hero.bounds)) { obstacleToTrack.alreadyHit = true; obstacleToTrack.rotation = deg2rad(70); hitObstacle = 30; playerSpeed *= 0.5; } if(obstacleToTrack.distance > 0) { obstacleToTrack.distance -= playerSpeed * elapsed; } else { if(obstacleToTrack.watchOut) { obstacleToTrack.watchOut = false; } obstacleToTrack.x -= (playerSpeed + obstacleToTrack.speed) * elapsed; } if(obstacleToTrack.x < -obstacleToTrack.width || gameState == "over") { obstaclesToAnimate.splice(i, 1); this.removeChild(obstacleToTrack); } } } private function checkElapsed(event:Event):void { timePrevious = timeCurrent; timeCurrent = getTimer(); elapsed = (timeCurrent - timePrevious) * 0.001; } private function createObstacle(type:Number, distance:Number):void{ var obstacle:Obstacle = new Obstacle(type, distance, true, 300); obstacle.x = stage.stageWidth; this.addChild(obstacle); if(type >= 4) { if(Math.random() > 0.5) { obstacle.y = gameArea.top; obstacle.position = "top" } else { obstacle.y = gameArea.bottom - obstacle.height; obstacle.position = "bottom"; } } else { obstacle.y = int(Math.random() * (gameArea.bottom - obstacle.height - gameArea.top)) + gameArea.top; obstacle.position = "middle"; } obstaclesToAnimate.push(obstacle); } } }

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  • Password hashing, salt and storage of hashed values

    - by Jonathan Leffler
    Suppose you were at liberty to decide how hashed passwords were to be stored in a DBMS. Are there obvious weaknesses in a scheme like this one? To create the hash value stored in the DBMS, take: A value that is unique to the DBMS server instance as part of the salt, And the username as a second part of the salt, And create the concatenation of the salt with the actual password, And hash the whole string using the SHA-256 algorithm, And store the result in the DBMS. This would mean that anyone wanting to come up with a collision should have to do the work separately for each user name and each DBMS server instance separately. I'd plan to keep the actual hash mechanism somewhat flexible to allow for the use of the new NIST standard hash algorithm (SHA-3) that is still being worked on. The 'value that is unique to the DBMS server instance' need not be secret - though it wouldn't be divulged casually. The intention is to ensure that if someone uses the same password in different DBMS server instances, the recorded hashes would be different. Likewise, the user name would not be secret - just the password proper. Would there be any advantage to having the password first and the user name and 'unique value' second, or any other permutation of the three sources of data? Or what about interleaving the strings? Do I need to add (and record) a random salt value (per password) as well as the information above? (Advantage: the user can re-use a password and still, probably, get a different hash recorded in the database. Disadvantage: the salt has to be recorded. I suspect the advantage considerably outweighs the disadvantage.) There are quite a lot of related SO questions - this list is unlikely to be comprehensive: Encrypting/Hashing plain text passwords in database Secure hash and salt for PHP passwords The necessity of hiding the salt for a hash Clients-side MD5 hash with time salt Simple password encryption Salt generation and Open Source software I think that the answers to these questions support my algorithm (though if you simply use a random salt, then the 'unique value per server' and username components are less important).

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  • Java HashSet using a specified method

    - by threenplusone
    I have a basic class 'HistoryItem' like so: public class HistoryItem private Date startDate; private Date endDate; private Info info; private String details; @Override public int hashCode() { int hash = (startDate == null ? 0 : startDate.hashCode()); hash = hash * 31 + (endDate == null ? 0 : endDate.hashCode()); return hash; } } I am currently using a HashSet to remove duplicates from an ArrayList on the startDate & endDate fields, which is working correctly. However I also need to remove duplicates on different fields (info & details). My question is this. Is there a way to specify a different method which HashSet will use in place of hashCode()? Something like this: public int hashCode_2() { int hash = (info == null ? 0 : info.hashCode()); hash = hash * 31 + (details == null ? 0 : details.hashCode()); return hash; } Set<HistoryItem> removeDups = new HashSet<HistoryItem>(); removeDups.setHashMethod(hashCode_2); Or is there another way that I should be doing this?

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  • assign characters to key combinations in XP or Visual Studio .Net

    - by cpj
    I'm running Mac OSX on a MacBookPro (UK keyboard). I run windows XP under parallels in a VM. I run Visual Studio .Net 2003 and 2008 in XP in the VM when i need to. I have English United Kingdom and English United states keyboards setup in XP. (they switch sometimes for no apparent reason) There is no hash "#" key on my mac's keyboard. However, in OSX I can get a hash with an alt+3 key combination. But In Windows XP... I can not make a "#" character. I can go to the character map in windows and copy a hash.. switch into OSX and copy a hash.. search in code and copy a hash.. but I can not make a hash in XP using my keyboard without typing U+0023: ... which you can imagine is annoying. coding anything with hash symbols is becoming a choir. Anyone got any advice or key mapping tricks I can use to get hash characters working in XP using my mac UK keyboard?

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  • Compute hash of class code at runtime (C#)?

    - by Breck Fresen
    Is it possible to compute the hash of a class at runtime in C# (presumably through reflection)? To be clear, I don't want to compute the hashcode of an instance of said class, I want to compute the hash of the class code itself (if a function in the class changes, I'd expect a different hash code to be computed). Ideally this would only be sensitive to changes in the object code (and not just a hash of the string representation of the code itself). Thanks in advance for your help, -- Breck

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  • Ruby: How can I have a Hash take multiple keys?

    - by zxcvbnm
    I'm taking 5 strings (protocol, source IP and port, destination IP and port) and using them to store some values in a hash. The problem is that if the IPs or ports are switched between source and destination, the key is supposed to be the same. If I was doing this in C#/Java/whatever I'd have to create a new class and overwrite the hashcode()/equals() methods, but that seems error prone from the little I've read about it and I was wondering if there would be a better alternative here.

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  • calling a function from static function

    - by iSight
    Hi, how can i call a function which computes with input parameters from an another static function. say, class X { static void xyz(); static int pqr(int, int); }; static X::void xyz() { ...pqr(10,20); } int X::pqr(int t1, int t2) { return t1*t2; }

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