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  • Weight doesn't work in a custom android component

    - by RCB
    I wanted to create a custom bottom button bar layout, I've created a xml file : <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" style="@android:style/ButtonBar" android:layout_width="fill_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:padding="0dp" > <Button android:id="@+id/media_menu_button" style="?android:attr/buttonStyleSmall" android:layout_width="0dp" android:layout_height="match_parent" android:layout_margin="0dp" android:layout_weight="1" android:text="@string/media_menu_button" /> <Button android:id="@+id/scenario_menu_button" style="?android:attr/buttonStyleSmall" android:layout_width="0dp" android:layout_height="match_parent" android:layout_margin="0dp" android:layout_weight="1" android:text="@string/scenario_menu_button" /> <Button android:id="@+id/rooms_menu_button" style="?android:attr/buttonStyleSmall" android:layout_width="0dp" android:layout_height="match_parent" android:layout_margin="0dp" android:layout_weight="1" android:text="@string/rooms_menu_button" /> <Button android:id="@+id/shortcut_menu_button" style="?android:attr/buttonStyleSmall" android:layout_width="0dp" android:layout_height="match_parent" android:layout_margin="0dp" android:layout_weight="1" android:text="@string/shortcut_menu_button" /> as you can see I've given all the buttons width 0dp and weight of 1. then, I've created a class that extends the linear layout class : public class BeLightBottomBar extends LinearLayout implements OnClickListener { private LayoutInflater mInflater; private Context contexnt; private Button mShortcutMenuButton; private Button mRoomsMenuButton; private Button mScenarioMenuButton; private Button mMediaMenuButton; public BeLightBottomBar(Context context, AttributeSet attrs) { super(context, attrs); //inflate the view this.contexnt = context; mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); LinearLayout barView = (LinearLayout) mInflater.inflate(R.layout.belight_bottombar, null); addView(barView); //get all the instances of the components of the bar mShortcutMenuButton = (Button) barView.findViewById(R.id.shortcut_menu_button); mRoomsMenuButton = (Button) barView.findViewById(R.id.rooms_menu_button); mScenarioMenuButton = (Button) barView.findViewById(R.id.scenario_menu_button); mMediaMenuButton = (Button) barView.findViewById(R.id.media_menu_button); //set this as a click listener mShortcutMenuButton.setOnClickListener(this); mRoomsMenuButton.setOnClickListener(this); mScenarioMenuButton.setOnClickListener(this); mMediaMenuButton.setOnClickListener(this); ... ... ... } the problem is when i add this class to the main activity xml <belight.homecontrol.components.BeLightBottomBar android:id="@+id/button_bar" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_alignParentBottom="true" android:layout_margin="0dp" android:padding="0dp" /> the weight stops working, all the buttons are different. and I don't know why !? if I just copy paste the bottom's bar xml code to the main xml file it works fine, the problem only occurs when using it as a whole. P.S. Is it a good practice to create a component this way? Or maybe I'm doing something wrong? Thanks, Dan

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  • Silverlight 4 Setting background color of textbox on focus

    - by Sean Riedel
    I am trying to set the background color of a Textbox to white on focus using a Style. My enabled Textbox has a Linear Gradient background by default: <Setter Property="Background"> <Setter.Value> <LinearGradientBrush StartPoint="0.5,0" EndPoint="0.5,1"> <GradientStop Color="#e8e8e8" Offset="0.0" /> <GradientStop Color="#f3f3f3" Offset="0.25" /> <GradientStop Color="#f4f4f4" Offset="0.75" /> <GradientStop Color="#f4f4f4" Offset="1.0" /> </LinearGradientBrush> </Setter.Value> </Setter> I have a focus visual state defined: <VisualStateGroup x:Name="FocusStates"> <VisualState x:Name="Focused"> <Storyboard> <DoubleAnimation Storyboard.TargetName="FocusVisualElement" Storyboard.TargetProperty="Opacity" To="1" Duration="0"/> </Storyboard> </VisualState> Here is the rest of the Control Template: <Border x:Name="Border" BorderThickness="{TemplateBinding BorderThickness}" CornerRadius="1" Opacity="1" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}"> <Grid> <Border x:Name="ReadOnlyVisualElement" Opacity="0" Background="#5EC9C9C9"/> <Border x:Name="MouseOverBorder" BorderThickness="1" BorderBrush="Transparent"> <ScrollViewer x:Name="ContentElement" Padding="{TemplateBinding Padding}" BorderThickness="0" IsTabStop="False"/> </Border> </Grid> </Border> <Border x:Name="DisabledVisualElement" Background="#A5D7D7D7" BorderBrush="#A5D7D7D7" BorderThickness="{TemplateBinding BorderThickness}" Opacity="0" IsHitTestVisible="False"/> <Border x:Name="FocusVisualElement" Background="#A5ffffff" BorderBrush="#FF72c1ec" BorderThickness="{TemplateBinding BorderThickness}" Margin="1" Opacity="0" IsHitTestVisible="False"/> On the last Border tag is where I am trying to set the background to white (#ffffff). Right now I have the opacity at A5 which does turn the background white, however it also starts to obscure the text in the box. Any higher opacity makes the text invisible so I am pretty sure that setting the background of that border is not the right way to do this. Can I set the Background color of the ContentElement somehow through a StoryBoard? Thanks.

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  • How to avoid using duplicate savepoint names in nested transactions in nested stored procs?

    - by Gary McGill
    I have a pattern that I almost always follow, where if I need to wrap up an operation in a transaction, I do this: BEGIN TRANSACTION SAVE TRANSACTION TX -- Stuff IF @error <> 0 ROLLBACK TRANSACTION TX COMMIT TRANSACTION That's served me well enough in the past, but after years of using this pattern (and copy-pasting the above code), I've suddenly discovered a flaw which comes as a complete shock. Quite often, I'll have a stored procedure calling other stored procedures, all of which use this same pattern. What I've discovered (to my cost) is that because I'm using the same savepoint name everywhere, I can get into a situation where my outer transaction is partially committed - precisely the opposite of the atomicity that I'm trying to achieve. I've put together an example that exhibits the problem. This is a single batch (no nested stored procs), and so it looks a little odd in that you probably wouldn't use the same savepoint name twice in the same batch, but my real-world scenario would be too confusing to post. CREATE TABLE Test (test INTEGER NOT NULL) BEGIN TRAN SAVE TRAN TX BEGIN TRAN SAVE TRAN TX INSERT INTO Test(test) VALUES (1) COMMIT TRAN TX BEGIN TRAN SAVE TRAN TX INSERT INTO Test(test) VALUES (2) COMMIT TRAN TX DELETE FROM Test ROLLBACK TRAN TX COMMIT TRAN TX SELECT * FROM Test DROP TABLE Test When I execute this, it lists one record, with value "1". In other words, even though I rolled back my outer transaction, a record was added to the table. What's happening is that the ROLLBACK TRANSACTION TX at the outer level is rolling back as far as the last SAVE TRANSACTION TX at the inner level. Now that I write this all out, I can see the logic behind it: the server is looking back through the log file, treating it as a linear stream of transactions; it doesn't understand the nesting/hierarchy implied by either the nesting of the transactions (or, in my real-world scenario, by the calls to other stored procedures). So, clearly, I need to start using unique savepoint names instead of blindly using "TX" everywhere. But - and this is where I finally get to the point - is there a way to do this in a copy-pastable way so that I can still use the same code everywhere? Can I auto-generate the savepoint name on the fly somehow? Is there a convention or best-practice for doing this sort of thing? It's not exactly hard to come up with a unique name every time you start a transaction (could base it off the SP name, or somesuch), but I do worry that eventually there would be a conflict - and you wouldn't know about it because rather than causing an error it just silently destroys your data... :-(

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  • Creating thousands of records in Rails

    - by willCosgrove
    Let me set the stage: My application deals with gift cards. When we create cards they have to have a unique string that the user can use to redeem it with. So when someone orders our gift cards, like a retailer, we need to make a lot of new card objects and store them in the DB. With that in mind, I'm trying to see how quickly I can have my application generate 100,000 Cards. Database expert, I am not, so I need someone to explain this little phenomena: When I create 1000 Cards, it takes 5 seconds. When I create 100,000 cards it should take 500 seconds right? Now I know what you're wanting to see, the card creation method I'm using, because the first assumption would be that it's getting slower because it's checking the uniqueness of a bunch of cards, more as it goes along. But I can show you my rake task desc "Creates cards for a retailer" task :order_cards, [:number_of_cards, :value, :retailer_name] => :environment do |t, args| t = Time.now puts "Searching for retailer" @retailer = Retailer.find_by_name(args[:retailer_name]) puts "Retailer found" puts "Generating codes" value = args[:value].to_i number_of_cards = args[:number_of_cards].to_i codes = [] top_off_codes(codes, number_of_cards) while codes != codes.uniq codes.uniq! top_off_codes(codes, number_of_cards) end stored_codes = Card.all.collect do |c| c.code end while codes != (codes - stored_codes) codes -= stored_codes top_off_codes(codes, number_of_cards) end puts "Codes are unique and generated" puts "Creating bundle" @bundle = @retailer.bundles.create!(:value => value) puts "Bundle created" puts "Creating cards" @bundle.transaction do codes.each do |code| @bundle.cards.create!(:code => code) end end puts "Cards generated in #{Time.now - t}s" end def top_off_codes(codes, intended_number) (intended_number - codes.size).times do codes << ReadableRandom.get(CODE_LENGTH) end end I'm using a gem called readable_random for the unique code. So if you read through all of that code, you'll see that it does all of it's uniqueness testing before it ever starts creating cards. It also writes status updates to the screen while it's running, and it always sits for a while at creating. Meanwhile it flies through the uniqueness tests. So my question to the stackoverflow community is: Why is my database slowing down as I add more cards? Why is this not a linear function in regards to time per card? I'm sure the answer is simple and I'm just a moron who knows nothing about data storage. And if anyone has any suggestions, how would you optimize this method, and how fast do you think you could get it to create 100,000 cards? (When I plotted out my times on a graph and did a quick curve fit to get my line formula, I calculated how long it would take to create 100,000 cards with my current code and it says 5.5 hours. That maybe completely wrong, I'm not sure. But if it stays on the line I curve fitted, it would be right around there.)

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  • LinearLayout - How to get text to be on the right of an icon?

    - by RED_
    Hi there, Bit of a newbie when it comes to android, only been working on it properly for a few days but even after all the searching I've done im stumped and nobody seems to know how to help me. I have this so far: http://img263.imageshack.us/i/sellscreen.jpg How can I move the text to be besides each icon rather than underneath it? Hoping the gallery won't be moved either. Here is the code i have: <?xml version="1.0" encoding="utf-8"?> <ScrollView xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/scroller" android:layout_width="fill_parent" android:layout_height="fill_parent" android:fillViewport="true" > <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <Gallery xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/gallery" android:layout_width="fill_parent" android:layout_height="wrap_content"/> <ImageView android:id="@+id/test_image" android:src="@drawable/icon" android:layout_width="wrap_content" android:layout_height="wrap_content"/> <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="The offcial UK driving theory test application. Over 190 questions." /> <ImageView android:id="@+id/test_image" android:src="@drawable/icon" android:layout_width="wrap_content" android:layout_height="wrap_content"/> <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="The offcial UK driving theory test application. Over 190 questions."/> <ImageView android:id="@+id/test_image" android:src="@drawable/icon" android:layout_width="wrap_content" android:layout_height="wrap_content"/> <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="The offcial UK driving theory test application. Over 190 questions."/> <ImageView android:id="@+id/test_image" android:src="@drawable/icon" android:layout_width="wrap_content" android:layout_height="wrap_content"/> <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="The offcial UK driving theory test application. Over 190 questions."/> <ImageView android:id="@+id/test_image" android:src="@drawable/icon" android:layout_width="wrap_content" android:layout_height="wrap_content" /> <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="The offcial UK driving theory test application. Over 190 questions." /> </LinearLayout> </ScrollView> Top half of my code doesn't seem to be showing for some reason but it's just the opening of the linear layout. I will be forever grateful to anyone that can help, i've been racking my brains for days and getting nowhere. Really getting stressed out by it. Thanks in advance!!

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  • How to interpolate hue values in HSV colour space?

    - by nick
    Hi, I'm trying to interpolate between two colours in HSV colour space to produce a smooth colour gradient. I'm using a linear interpolation, eg: h = (1 - p) * h1 + p * h2 s = (1 - p) * s1 + p * s2 v = (1 - p) * v1 + p * v2 (where p is the percentage, and h1, h2, s1, s2, v1, v2 are the hue, saturation and value components of the two colours) This produces a good result for s and v but not for h. As the hue component is an angle, the calculation needs to work out the shortest distance between h1 and h2 and then do the interpolation in the right direction (either clockwise or anti-clockwise). What formula or algorithm should I use? EDIT: By following Jack's suggestions I modified my JavaScript gradient function and it works well. For anyone interested, here's what I ended up with: // create gradient from yellow to red to black with 100 steps var gradient = hsbGradient(100, [{h:0.14, s:0.5, b:1}, {h:0, s:1, b:1}, {h:0, s:1, b:0}]); function hsbGradient(steps, colours) { var parts = colours.length - 1; var gradient = new Array(steps); var gradientIndex = 0; var partSteps = Math.floor(steps / parts); var remainder = steps - (partSteps * parts); for (var col = 0; col < parts; col++) { // get colours var c1 = colours[col], c2 = colours[col + 1]; // determine clockwise and counter-clockwise distance between hues var distCCW = (c1.h >= c2.h) ? c1.h - c2.h : 1 + c1.h - c2.h; distCW = (c1.h >= c2.h) ? 1 + c2.h - c1.h : c2.h - c1.h; // ensure we get the right number of steps by adding remainder to final part if (col == parts - 1) partSteps += remainder; // make gradient for this part for (var step = 0; step < partSteps; step ++) { var p = step / partSteps; // interpolate h var h = (distCW <= distCCW) ? c1.h + (distCW * p) : c1.h - (distCCW * p); if (h < 0) h = 1 + h; if (h > 1) h = h - 1; // interpolate s, b var s = (1 - p) * c1.s + p * c2.s; var b = (1 - p) * c1.b + p * c2.b; // add to gradient array gradient[gradientIndex] = {h:h, s:s, b:b}; gradientIndex ++; } } return gradient; }

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  • physics game programming box2d - orientating a turret-like object using torques

    - by egarcia
    This is a problem I hit when trying to implement a game using the LÖVE engine, which covers box2d with Lua scripting. The objective is simple: A turret-like object (seen from the top, on a 2D environment) needs to orientate itself so it points to a target. The turret is on the x,y coordinates, and the target is on tx, ty. We can consider that x,y are fixed, but tx, ty tend to vary from one instant to the other (i.e. they would be the mouse cursor). The turret has a rotor that can apply a rotational force (torque) on any given moment, clockwise or counter-clockwise. The magnitude of that force has an upper limit called maxTorque. The turret also has certain rotational inertia, which acts for angular movement the same way mass acts for linear movement. There's no friction of any kind, so the turret will keep spinning if it has an angular velocity. The turret has a small AI function that re-evaluates its orientation to verify that it points to the right direction, and activates the rotator. This happens every dt (~60 times per second). It looks like this right now: function Turret:update(dt) local x,y = self:getPositon() local tx,ty = self:getTarget() local maxTorque = self:getMaxTorque() -- max force of the turret rotor local inertia = self:getInertia() -- the rotational inertia local w = self:getAngularVelocity() -- current angular velocity of the turret local angle = self:getAngle() -- the angle the turret is facing currently -- the angle of the like that links the turret center with the target local targetAngle = math.atan2(oy-y,ox-x) local differenceAngle = _normalizeAngle(targetAngle - angle) if(differenceAngle <= math.pi) then -- counter-clockwise is the shortest path self:applyTorque(maxTorque) else -- clockwise is the shortest path self:applyTorque(-maxTorque) end end ... it fails. Let me explain with two illustrative situations: The turret "oscillates" around the targetAngle. If the target is "right behind the turret, just a little clock-wise", the turret will start applying clockwise torques, and keep applying them until the instant in which it surpasses the target angle. At that moment it will start applying torques on the opposite direction. But it will have gained a significant angular velocity, so it will keep going clockwise for some time... until the target will be "just behind, but a bit counter-clockwise". And it will start again. So the turret will oscillate or even go in round circles. I think that my turret should start applying torques in the "opposite direction of the shortest path" before it reaches the target angle (like a car braking before stopping). Intuitively, I think the turret should "start applying torques on the opposite direction of the shortest path when it is about half-way to the target objective". My intuition tells me that it has something to do with the angular velocity. And then there's the fact that the target is mobile - I don't know if I should take that into account somehow or just ignore it. How do I calculate when the turret must "start braking"?

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  • Error at lapack cgesv when matrix is not singular

    - by Jan Malec
    This is my first post. I usually ask classmates for help, but they have a lot of work now and I'm too desperate to figure this out on my own :). I am working on a project for school and I have come to a point where I need to solve a system of linear equations with complex numbers. I have decided to call lapack routine "cgesv" from c++. I use the c++ complex library to work with complex numbers. Problem is, when I call the routine, I get error code "2". From lapack documentation: INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value > 0: if INFO = i, U(i,i) is exactly zero. The factorization has been completed, but the factor U is exactly singular, so the solution could not be computed. Therefore, the element U(2, 2) should be zero, but it is not. This is how I declare the function: void cgesv_( int* N, int* NRHS, std::complex* A, int* lda, int* ipiv, std::complex* B, int* ldb, int* INFO ); This is how I use it: int *IPIV = new int[NA]; int INFO, NRHS = 1; std::complex<double> *aMatrix = new std::complex<double>[NA*NA]; for(int i=0; i<NA; i++){ for(int j=0; j<NA; j++){ aMatrix[j*NA+i] = A[i][j]; } } cgesv_( &NA, &NRHS, aMatrix, &NA, IPIV, B, &NB, &INFO ); And this is how the matrix looks like: (1,-160.85) (0,0.000306796) (0,-0) (0,-0) (0,-0) (0,0.000306796) (1,-40.213) (0,0.000306796) (0,-0) (0,-0) (0,-0) (0,0.000306796) (1,-0.000613592) (0,0.000306796) (0,-0) (0,-0) (0,-0) (0,0.000306796) (1,-40.213) (0,0.000306796) (0,-0) (0,-0) (0,-0) (0,0.000306796) (1,-160.85) I had to split the matrix colums, otherwise it did not format correctly. My first suspicion was that complex is not parsed correctly, but I have used lapack functions with complex numbers before this way. Any ideas?

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  • AD - DirectoryServices: VBNET2.0 - Speaking architecture...

    - by Will Marcouiller
    I've been mandated to write an application to migrate the Active Directory access models to another environment. Here's the context: I'm stuck with VB.NET 2005 and .NET Framework 2.0; The application must use the Windows authenticated user to manage AD; The objects I have to handle are Groups, Users and OrganizationalUnits; I intend to use the Façade design pattern to provider ease of use and a fully reusable code; I plan to write a factory for each of the objects managed (group, ou, user); The use of Attributes should be useful here, I guess; As everything is about the DirectoryEntry class when accessing the AD, it seems a good candidate for generic types. Obligatory features: User creates new OUs manually; User creates new group manually; User creates new user (these users are services accounts) manually; Application reads an XML file which contains the OUs, groups and users to create; Application informs the user about the OUs, groups and users that shall be created; User specifies the domain environment where to migrate the XML input file designated objects; User makes changes if needed, and launches the task operations; Application performs required by the XML input file operations against the underlying AD as specified by the user; Application informs the user upon completion. Linear features: User fetches OUs, groups, users; User changes OUs, groups, users; User deletes OUs, groups, users; The application logs AD entries and operations performed, plus errors and exceptions; Nice-to-have features: Application rollbacks operations on error or exception. I've been working for weeks now to get acquainted with the AD and the System.DirectoryServices assembly. But I don't seem to find a way to be fully satisfied with what I'm doing and always looking for better. I have studied Bret de Smet's Linq to AD on CodePlex, but then again, I can't use it as I'm stuck with .NET 2.0, so no Linq! But I've learned about Attributes, and seen that he's working with generic types as he codes a DirectorySource class to perform the operations for OUs, groups and users. Any suggestions? Thanks for any help, code sample, ideas, architural solution, everything!

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  • Animating gradient displays line artifacts in ActionScript

    - by TheDarkIn1978
    i've programatically created a simple gradient (blue to red) sprite rect using my own basic class called GradientRect, but moving or animation the sprite exhibits line artifacts. when the sprite is rotating, it kind of resembles bad reception of an old television set. i'm almost certain the cause is because each line slice of the gradient is vector so there are gaps between the lines - this is visible when the sprite is zoomed in. var colorPickerRect:GradientRect = new GradientRect(200, 200, 0x0000FF, 0xFF0000); addChild(colorPickerRect); colorPickerRect.cacheAsBitmap = true; colorPickerRect.x = colorPickerRect.y = 100; colorPickerRect.addEventListener(Event.ENTER_FRAME, rotate); function rotate(evt:Event):void { evt.target.rotation += 1; } ________________________ //CLASS PACKAGE package { import flash.display.CapsStyle; import flash.display.GradientType; import flash.display.LineScaleMode; import flash.display.Sprite; import flash.geom.Matrix; public class GradientRect extends Sprite { public function GradientRect(gradientRectWidth:Number, gradientRectHeight:Number, ...leftToRightColors) { init(gradientRectWidth, gradientRectHeight, leftToRightColors); } private function init(gradientRectWidth:Number, gradientRectHeight:Number, leftToRightColors:Array):void { var leftToRightAlphas:Array = new Array(); var leftToRightRatios:Array = new Array(); var leftToRightPartition:Number = 255 / (leftToRightColors.length - 1); var pixelColor:Number; var i:int; //Push arrays for (i = 0; i < leftToRightColors.length; i++) { leftToRightAlphas.push(1); leftToRightRatios.push(i * leftToRightPartition); } //Graphics matrix and lineStyle var leftToRightColorsMatrix:Matrix = new Matrix(); leftToRightColorsMatrix.createGradientBox(gradientRectWidth, 1); graphics.lineStyle(1, 0, 1, false, LineScaleMode.NONE, CapsStyle.NONE); for (i = 0; i < gradientRectWidth; i++) { graphics.lineGradientStyle(GradientType.LINEAR, leftToRightColors, leftToRightAlphas, leftToRightRatios, leftToRightColorsMatrix); graphics.moveTo(i, 0); graphics.lineTo(i, gradientRectHeight); } } } } how can i solve this problem?

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  • difference equations in MATLAB - why the need to switch signs?

    - by jefflovejapan
    Perhaps this is more of a math question than a MATLAB one, not really sure. I'm using MATLAB to compute an economic model - the New Hybrid ISLM model - and there's a confusing step where the author switches the sign of the solution. First, the author declares symbolic variables and sets up a system of difference equations. Note that the suffixes "a" and "2t" both mean "time t+1", "2a" means "time t+2" and "t" means "time t": %% --------------------------[2] MODEL proc-----------------------------%% % Define endogenous vars ('a' denotes t+1 values) syms y2a pi2a ya pia va y2t pi2t yt pit vt ; % Monetary policy rule ia = q1*ya+q2*pia; % ia = q1*(ya-yt)+q2*pia; %%option speed limit policy % Model equations IS = rho*y2a+(1-rho)yt-sigma(ia-pi2a)-ya; AS = beta*pi2a+(1-beta)*pit+alpha*ya-pia+va; dum1 = ya-y2t; dum2 = pia-pi2t; MPs = phi*vt-va; optcon = [IS ; AS ; dum1 ; dum2; MPs]; He then computes the matrix A: %% ------------------ [3] Linearization proc ------------------------%% % Differentiation xx = [y2a pi2a ya pia va y2t pi2t yt pit vt] ; % define vars jopt = jacobian(optcon,xx); % Define Linear Coefficients coef = eval(jopt); B = [ -coef(:,1:5) ] ; C = [ coef(:,6:10) ] ; % B[c(t+1) l(t+1) k(t+1) z(t+1)] = C[c(t) l(t) k(t) z(t)] A = inv(C)*B ; %(Linearized reduced form ) As far as I understand, this A is the solution to the system. It's the matrix that turns time t+1 and t+2 variables into t and t+1 variables (it's a forward-looking model). My question is essentially why is it necessary to reverse the signs of all the partial derivatives in B in order to get this solution? I'm talking about this step: B = [ -coef(:,1:5) ] ; Reversing the sign here obviously reverses the sign of every component of A, but I don't have a clear understanding of why it's necessary. My apologies if the question is unclear or if this isn't the best place to ask.

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  • TicTacToe AI Making Incorrect Decisions

    - by Chris Douglass
    A little background: as a way to learn multinode trees in C++, I decided to generate all possible TicTacToe boards and store them in a tree such that the branch beginning at a node are all boards that can follow from that node, and the children of a node are boards that follow in one move. After that, I thought it would be fun to write an AI to play TicTacToe using that tree as a decision tree. TTT is a solvable problem where a perfect player will never lose, so it seemed an easy AI to code for my first time trying an AI. Now when I first implemented the AI, I went back and added two fields to each node upon generation: the # of times X will win & the # of times O will win in all children below that node. I figured the best solution was to simply have my AI on each move choose and go down the subtree where it wins the most times. Then I discovered that while it plays perfect most of the time, I found ways where I could beat it. It wasn't a problem with my code, simply a problem with the way I had the AI choose it's path. Then I decided to have it choose the tree with either the maximum wins for the computer or the maximum losses for the human, whichever was more. This made it perform BETTER, but still not perfect. I could still beat it. So I have two ideas and I'm hoping for input on which is better: 1) Instead of maximizing the wins or losses, instead I could assign values of 1 for a win, 0 for a draw, and -1 for a loss. Then choosing the tree with the highest value will be the best move because that next node can't be a move that results in a loss. It's an easy change in the board generation, but it retains the same search space and memory usage. Or... 2) During board generation, if there is a board such that either X or O will win in their next move, only the child that prevents that win will be generated. No other child nodes will be considered, and then generation will proceed as normal after that. It shrinks the size of the tree, but then I have to implement an algorithm to determine if there is a one move win and I think that can only be done in linear time (making board generation a lot slower I think?) Which is better, or is there an even better solution?

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  • random, Graphics point ,searching- algorithm, via dual for loop set

    - by LoneXcoder
    hello and thanks for joining me in my journey to the custom made algorithm for "guess where the pixel is" this for Loop set (over Point.X, Point.Y), is formed in consecutive/linear form: //Original\initial Location Point initPoint = new Point(150, 100); // No' of pixels to search left off X , and above Y int preXsrchDepth, preYsrchDepth; // No' of pixels to search to the right of X, And Above Y int postXsrchDepth, postYsrchDepth; preXsrchDepth = 10; // will start search at 10 pixels to the left from original X preYsrchDepth = 10; // will start search at 10 pixels above the original Y postXsrchDepth = 10; // will stop search at 10 pixels to the right from X postYsrchDepth = 10; // will stop search at 10 pixels below Y int StopXsearch = initPoint.X + postXsrchDepth; //stops X Loop itarations at initial pointX + depth requested to serch right of it int StopYsearch = initPoint.Y + postYsrchDepth; //stops Y Loop itarations at initial pointY + depth requested below original location int CountDownX, CountDownY; // Optional not requierd for loop but will reports the count down how many iterations left (unless break; triggerd ..uppon success) Point SearchFromPoint = Point.Empty; //the point will be used for (int StartX = initPoint.X - preXsrchDepth; StartX < StopXsearch; StartX++) { SearchFromPoint.X = StartX; for (int StartY = initPoint.Y - preYsrchDepth; StartY < StpY; StartY++) { CountDownX = (initPoint.X - StartX); CountDownY=(initPoint.Y - StartY); SearchFromPoint.Y = StartY; if (SearchSuccess) { same = true; AAdToAppLog("Search Report For: " + imgName + "Search Completed Successfully On Try " + CountDownX + ":" + CountDownY); break; } } } <-10 ---- -5--- -1 X +1--- +5---- +10 what i would like to do is try a way of instead is have a little more clever approach <+8---+5-- -8 -5 -- +2 +10 X -2 - -10 -8-- -6 ---1- -3 | +8 | -10 Y +1 -6 | | +9 .... I do know there's a wheel already invented in this field (even a full-trailer truck amount of wheels (: ) but as a new programmer, I really wanted to start of with a simple way and also related to my field of interest in my project. can anybody show an idea of his, he learnt along the way to Professionalism in algorithm /programming having tests to do on few approaches (kind'a random cleverness...) will absolutely make the day and perhaps help some others viewing this page in the future to come it will be much easier for me to understand if you could use as much as possible similar naming to variables i used or implenet your code example ...it will be Greatly appreciated if used with my code sample, unless my metod is a realy flavorless. p.s i think that(atleast as human being) the tricky part is when throwing inconsecutive numbers you loose track of what you didn't yet use, how do u take care of this too . thanks allot in advance looking forward to your participation !

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  • AD-DirectoryServices: .NET2.0 - Speaking architecture, approach and best practices... Suggestions?

    - by Will Marcouiller
    I've been mandated to write an application to migrate the Active Directory access models to another environment. Here's the context: I'm stuck with VB.NET 2005 and .NET Framework 2.0; The application must use the Windows authenticated user to manage AD; The objects I have to handle are Groups, Users and OrganizationalUnits; I intend to use the Façade design pattern to provider ease of use and a fully reusable code; I plan to write a factory for each of the objects managed (group, ou, user); The use of Attributes should be useful here, I guess; As everything is about the DirectoryEntry class when accessing the AD, it seems a good candidate for generic types. Obligatory features: User creates new OUs manually; User creates new group manually; User creates new user (these users are services accounts) manually; Application reads an XML file which contains the OUs, groups and users to create; Application informs the user about the OUs, groups and users that shall be created; User specifies the domain environment where to migrate the XML input file designated objects; User makes changes if needed, and launches the task operations; Application performs required by the XML input file operations against the underlying AD as specified by the user; Application informs the user upon completion. Linear features: User fetches OUs, groups, users; User changes OUs, groups, users; User deletes OUs, groups, users; The application logs AD entries and operations performed, plus errors and exceptions; Nice-to-have features: Application rollbacks operations on error or exception. I've been working for weeks now to get acquainted with the AD and the System.DirectoryServices assembly. But I don't seem to find a way to be fully satisfied with what I'm doing and always looking for better. I have studied Bret de Smet's Linq to AD on CodePlex, but then again, I can't use it as I'm stuck with .NET 2.0, so no Linq! But I've learned about Attributes, and seen that he's working with generic types as he codes a DirectorySource class to perform the operations for OUs, groups and users. I have been able to add groups to the AD; I have been able to add users to the AD; The created user is automatically disabled? I seem to get confused with the use of a LDAP path to add objects. For instance, one needs two instances of a System.DirectoryServices.DirectoryEntry class to add a group, for instance. Why this? Any suggestions? Thanks for any help, code sample, ideas, architural solution, everything!

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  • How to configure the framesize using AudioUnit.framework on iOS

    - by Piperoman
    I have an audio app i need to capture mic samples to encode into mp3 with ffmpeg First configure the audio: /** * We need to specifie our format on which we want to work. * We use Linear PCM cause its uncompressed and we work on raw data. * for more informations check. * * We want 16 bits, 2 bytes (short bytes) per packet/frames at 8khz */ AudioStreamBasicDescription audioFormat; audioFormat.mSampleRate = SAMPLE_RATE; audioFormat.mFormatID = kAudioFormatLinearPCM; audioFormat.mFormatFlags = kAudioFormatFlagIsPacked | kAudioFormatFlagIsSignedInteger; audioFormat.mFramesPerPacket = 1; audioFormat.mChannelsPerFrame = 1; audioFormat.mBitsPerChannel = audioFormat.mChannelsPerFrame*sizeof(SInt16)*8; audioFormat.mBytesPerPacket = audioFormat.mChannelsPerFrame*sizeof(SInt16); audioFormat.mBytesPerFrame = audioFormat.mChannelsPerFrame*sizeof(SInt16); The recording callback is: static OSStatus recordingCallback(void *inRefCon, AudioUnitRenderActionFlags *ioActionFlags, const AudioTimeStamp *inTimeStamp, UInt32 inBusNumber, UInt32 inNumberFrames, AudioBufferList *ioData) { NSLog(@"Log record: %lu", inBusNumber); NSLog(@"Log record: %lu", inNumberFrames); NSLog(@"Log record: %lu", (UInt32)inTimeStamp); // the data gets rendered here AudioBuffer buffer; // a variable where we check the status OSStatus status; /** This is the reference to the object who owns the callback. */ AudioProcessor *audioProcessor = (__bridge AudioProcessor*) inRefCon; /** on this point we define the number of channels, which is mono for the iphone. the number of frames is usally 512 or 1024. */ buffer.mDataByteSize = inNumberFrames * sizeof(SInt16); // sample size buffer.mNumberChannels = 1; // one channel buffer.mData = malloc( inNumberFrames * sizeof(SInt16) ); // buffer size // we put our buffer into a bufferlist array for rendering AudioBufferList bufferList; bufferList.mNumberBuffers = 1; bufferList.mBuffers[0] = buffer; // render input and check for error status = AudioUnitRender([audioProcessor audioUnit], ioActionFlags, inTimeStamp, inBusNumber, inNumberFrames, &bufferList); [audioProcessor hasError:status:__FILE__:__LINE__]; // process the bufferlist in the audio processor [audioProcessor processBuffer:&bufferList]; // clean up the buffer free(bufferList.mBuffers[0].mData); //NSLog(@"RECORD"); return noErr; } With data: inBusNumber = 1 inNumberFrames = 1024 inTimeStamp = 80444304 // All the time same inTimeStamp, this is strange However, the framesize that i need to encode mp3 is 1152. How can i configure it? If i do buffering, that implies a delay, but i would like to avoid this because is a real time app. If i use this configuration, each buffer i get trash trailing samples, 1152 - 1024 = 128 bad samples. All samples are SInt16.

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  • Collision point of 2 curves in a 3d-room

    - by Frank
    Hello, i am programming a small game for quite some time. We started coding a small FPS-Shooter inside of a project at school to get a bit experience using directX. I dont know why, but i couldnt stop the project and started programming at home aswell. At the moment i am trying to create some small AI. Of cause thats definatlly not easy, but thats my personal goal anyways. The topic could prolly fill multiple books hehe. I've got the walking part of my bots done so far. They walk along a scriped path. I am not working on the "aiming" of the bots. While programming that i hit on some math problem i couldnt solve yet. I hope of your input on this to help me get further. Concepts, ideas and everything else are highly appreciated. Problem: Calculate the position (D3DXVECTOR3) where the curve of the projectile (depends on gravity, speed), hit the curved of the enemys walking path (depends on speed). We assume that the enemy walks in a constant line. Known variables: float projectilSpeed = 2000 m/s //speed of the projectile per second float gravitation = 9.81 m/s^2 //of cause the gravity lol D3DXVECTOR3 targetPosition //position of the target stored in a vector (x,y,z) D3DXVECTOR3 projectilePosition //position of the projectile D3DXVECTOR3 targetSpeed //stores the change of the targets position in the last second Variabledefinition ProjectilePosition at time of collision = ProjectilePos_t TargetPosition at time of collision = TargetPos_t ProjectilePosition at time 0, now = ProjectilePos_0 TargetPosition at time 0, now = TargetPos_0 Time to impact = t Aim-angle = theta My try: Found a formular to calculate "drop" (Drop of the projectile based on the gravity) on Wikipedia: float drop = 0.5f * gravity * t * t The speed of the projectile has a horizontal and a vertical part.. Found a formular for that on wikipedia aswell: ProjectilVelocity.x = projectilSpeed * cos(theta) ProjectilVelocity.y = projectilSpeed * sin(theta) So i would assume this is true for the projectile curve: ProjectilePos_t.x = ProjectilePos_0.x + ProjectileSpeed * t ProjectilePos_t.y = ProjectilePos_0.y + ProjectileSpeed * t + 0.5f * gravity * t * t ProjectilePos_t.z = ProjectilePos_0.z + ProjectileSpeed * t The target walk with a constant speed, so we can determine his curve by this: TargetPos_t = TargetPos_0 + TargetSpeed * D3DXVECTOR3(t, t, t) Now i dont know how to continue. I have to solve it somehow to get a hold on the time to impact somehow. As a basic formular i could use: float time = distanz / projectileSpeed But that wouldnt be truly correct as it would assume a linear "Trajectory". We just find this behaivor when using a rocket. I hope i was able to explain the problem as much as possible. If there are questions left, feel free to ask me! Greets from germany, Frank

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  • What is a good platform for building a game framework targetting both web and native languages?

    - by fuzzyTew
    I would like to develop (or find, if one is already in development) a framework with support for accelerated graphics and sound built on a system flexible enough to compile to the following: native ppc/x86/x86_64/arm binaries or a language which compiles to them javascript actionscript bytecode or a language which compiles to it (actionscript 3, haxe) optionally java I imagine, for example, creating an API where I can open windows and make OpenGL-like calls and the framework maps this in a relatively efficient manner to either WebGL with a canvas object, 3d graphics in Flash, OpenGL ES 2 with EGL, or desktop OpenGL in an X11, Windows, or Cocoa window. I have so far looked into these avenues: Building the game library in haXe Pros: Targets exist for php, javascript, actionscript bytecode, c++ High level, object oriented language Cons: No support for finally{} blocks or destructors, making resource cleanup difficult C++ target does not allow room for producing highly optimized libraries -- the foreign function interface requires all primitive types be boxed in a wrapper object, as if writing bindings for a scripting language; these feel unideal for real-time graphics and audio, especially exporting low-level functions. Doesn't seem quite yet mature Using the C preprocessor to create a translator, writing programs entirely with macros Pros: CPP is widespread and simple to use Cons: This is an arduous task and probably the wrong tool for the job CPP implementations differ widely in support for features (e.g. xcode cpp has no variadic macros despite claiming C99 compliance) There is little-to-no room for optimization in this route Using llvm's support for multiple backends to target c/c++ to web languages Pros: Can code in c/c++ LLVM is a very mature highly optimizing compiler performing e.g. global inlining Targets exist for actionscript (alchemy) and javascript (emscripten) Cons: Actionscript target is closed source, unmaintained, and buggy. Javascript targets do not use features of HTML5 for appropriate optimization (e.g. linear memory with typed arrays) and are immature An LLVM target must convert from low-level bytecode, so high-level constructs are lost and bloated unreadable code is created from translating individual instructions, which may be more difficult for an unprepared JIT to optimize. "jump" instructions cause problems for languages with no "goto" statements. Using libclang to write a translator from C/C++ to web languages Pros: A beautiful parsing library providing easy access to the code structure Can code in C/C++ Has sponsored developer effort from Apple Cons: Incomplete; current feature set targets IDEs. Basic operators are unexposed and must be manually parsed from the returned AST element to be identified. Translating code prior to compilation may forgo optimizations assumed in c/c++ such as inlining. Creating new code generators for clang to translate into web languages Pros: Can code in C/C++ as libclang Cons: There is no API; code structure is unstable A much larger job than using libclang; the innards of clang are complex Building the game library in Common Lisp Pros: Flexible, ancient, well-developed language Extensive introspection should ease writing translators Translators exist for at least javascript Cons: Unfamiliar language No standardized library functions, widely varying implementations Which of these avenues should I pursue? Do you know of any others, or any systems that might be useful? Does a general project like this exist somewhere already? Thank you for any input.

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  • measure rendered html in javascript without affecting the measurement

    - by drawnonward
    I am doing pagination in javascript. This is typographic pagination, not chopping up database results. For the most part it works, but I have run into a heisenberg issue where I cannot quite measure text without affecting it. I am not trying to measure text before it is rendered. I want the actual position it shows up at on screen, so I can paginate to where it is naturally wrapped. I am measuring the vertical position of characters, not the horizontal width of strings. The way I do this is similar to this answer in that I am applying a style to a block of text, then measuring the position of the newly created span. If the span does not reach the end of the page, I clear it and make a new span in a linear search. The problem is that the anti-aliased sub-pixel text layout is different when the span is applied. In rare cases, this causes the text to wrap differently when I measure it. I have only seen this when wrapping at a hyphen, and I assume it would not happen when wrapping at white space. As a concrete example, "prepared-he" is the string I am having trouble with. When I measure up to "prepare" it appears, as expected, to be within the current page. When I measure "prepared" the whole phrase wraps down to the next line, moving it to the next page, so it looks like the "d" is the character to break at. I break the text between "prepare" and "d-he" and that is wrong. Trying to evaluate individual characters opens a whole can of worms I would rather avoid. The wrapping changes because, with the new span, the line is 1 pixel wider. A solution to my problem could either be a better way to measure text using javascript, or a way to wrap text in a new element without affecting layout. I have tried setting margin-right:-1px for the class of the span being created to wrap the text. This had no noticeable effect. I am doing this in a UIWebView on the iPhone. There are some measurement related calls that are available in normal WebKit that are not available here. For example, Range does not have getBoundingClientRect or support setting an offset other than 0 in setStart or setEnd. Thank you

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  • How to set background in OpenGL captured image from OpenCV

    - by user325487
    Hey All, i'm relatively new to Artoolkitplus and openGL i'm having a tough time getting the image i capture through openCV to be set as the background image in OpenGL ... I also cannot convert the image i take through the camera using opencv to be scaled to 320x280 from 640x480 .. i also have to save my image and load if for things to work... here's my code //////////// int findMarker() { IplImage* image = cvQueryFrame( capture ); if( !capture ) { fprintf( stderr, "ERROR: capture is NULL \n" ); getchar(); return -1; } if( !image ) { fprintf( stderr, "ERROR: frame is null...\n" ); getchar(); } //cvShowImage( "Capture", frame ); //image = cvCloneImage( frame ); try{ if(!cvSaveImage("immagineTmp.jpg",image)) printf("Could not save\n"); } catch(void*) {} image = cvLoadImage("immagineTmp.jpg", 1); cvShowImage( "Image", image ); glLoadIdentity(); ////////////// glDisable(GL_DEPTH_TEST); glOrtho(0,640,0,480,-1,1); glGenTextures(1, &bgid); glBindTexture(GL_TEXTURE_2D, bgid); // Create Linear Filtered Texture glBindTexture(GL_TEXTURE_2D, bgid); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); glTexImage2D(GL_TEXTURE_2D, 0, 3, image-width, image-height, 0, GL_RGB, GL_UNSIGNED_BYTE, image-imageData); glBindTexture(GL_TEXTURE_2D, bgid); glBegin(GL_QUADS); glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.2f, -1.0f, -2.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.2f, -1.0f, -2.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.2f, 1.0f, -2.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.2f, 1.0f, -2.0f); glEnd(); glEnable(GL_DEPTH_TEST); glLoadIdentity(); //////////// // do the OpenGL camera setup glMatrixMode(GL_PROJECTION); glLoadMatrixf(tracker-getProjectionMatrix()); int markerId = tracker-calc((unsigned char *)(image-imageData)); float conf = tracker-getConfidence(); // use the result of calc() to setup the OpenGL transformation glMatrixMode(GL_MODELVIEW); glLoadMatrixf(tracker-getModelViewMatrix()); if(markerId!=-1) { printf("\n\nFound marker %d (confidence %d%%)\n\nPose-Matrix:\n ", markerId, (int(conf*100.0f))); for(int i=0; i<16; i++) printf("%.2f %s", tracker-getModelViewMatrix()[i], (i%4==3)?"\n " : ""); } cvReleaseImage(&image); return 0; }

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  • Patterns for dynamic CMS components (event driven?)

    - by CitrusTree
    Sorry my title is not great, this is my first real punt at moving 100% to OO as I've been procedural for more years than I can remember. I'm finding it hard to understand if what I'm trying to do is possible. Depending on people's thoughts on the 2 following points, I'll go down that route. The CMS I'm putting together is quote small, however focuses very much on different types of content. I could easily use Drupal which I'm very comfortable with, but I want to give myself a really good reasons to move myself into design patterns / OO-PHP 1) I have created a base 'content' class which I wish to be able to extend to handle different types of content. The base class, for example, handles HTML content, and extensions might handle XML or PDF output instead. On the other hand, at some point I may wish to extend the base class for a given project completely. I.e. if class 'content-v2' extended class 'content' for that site, any calls to that class should actually call 'content-v2' instead. Is that possible? If the code instantiates an object of type 'content' - I actually want it to instantiate one of type 'content-v2'... I can see how to do it using inheritance, but that appears to involve referring to the class explicitly, I can't see how to link the class I want it to use instead dynamically. 2) Secondly, the way I'm building this at the moment is horrible, I'm not happy with it. It feels very linear indeed - i.e. get session details get content build navigation theme page publish. To do this all the objects are called 1-by-1 which is all very static. I'd like it to be more dynamic so that I can add to it at a later date (very closely related to first question). Is there a way that instead of my orchestrator class calling all the other classes 1-by-1, then building the whole thing up at the end, that instead each of the other classes can 'listen' for specific events, then at the applicable point jump in and do their but? That way the orchestrator class would not need to know what other classes were required, and call them 1-by-1. Sorry if I've got this all twisted in my head. I'm trying to build this so it's really flexible.

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  • Create a Color Picker, similar to Photoshop's, using Javascript and HTML Canvas

    - by André Alçada Padez
    I am not at all versed in Computer Graphics and am in need of creating a color picker as a javascript tool to embed in an HTML page. First, and looking at Photoshop's one, i thought of the RGB palette as a three-dimensional matrix. My first attempt envolved: <script type="text/javascript"> var rgCanvas = document.createElement('canvas'); rgCanvas.width = 256; rgCanvas.height = 256; rgCanvas.style.border = '3px solid black'; for (g = 0; g < 256; g++){ for (r = 0; r < 256; r++){ var context = rgCanvas.getContext('2d'); context.beginPath(); context.moveTo(r,g); context.strokeStyle = 'rgb(' + r + ', ' + g + ', 0)'; context.lineTo(r+1,g+1); context.stroke(); context.closePath(); } } var bCanvas = document.createElement('canvas'); bCanvas.width = 20; bCanvas.height = 256; bCanvas.style.border = '3px solid black'; for (b = 0; b < 256; b++){ var context = bCanvas.getContext('2d'); context.beginPath(); context.moveTo(0,b); context.strokeStyle = 'rgb(' + 0 + ', ' + 0 + ', ' + b + ')'; context.lineTo(20, b); context.stroke(); context.closePath(); } document.body.appendChild(rgCanvas); document.body.appendChild(bCanvas); </script> this results in something like My thought is this is too linear, comparing to the ones i see in Photoshop and on the web. I would like to know the logic behind the color mapping in a picker like this: I don't really need the algorythms itself, i'm mainly trying to understand the logic. Thanks

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  • What alternatives do I have for source control and does GIT does that?

    - by RubberDuck
    I work as a freelancer programmer for some clients and also create apps for myself. When I work for myself, obviously I work alone. I generally don't work in a linear way. My big problems today are: I have a lot of apps that use the same classes I have developed; In the past, I put all these common classes on a directory outside all projects and included them on my apps using absolute paths, but this method sucks because by accident (if you forget) you may change a path or the disk and all projects are broken. Then I decided to copy those classes to my projects every time. Because the majority of these classes do not change frequently, I am relatively ok, but when they change, I am in hell; When I change one of these classes I have to propagate the changes to all other apps using copies of them. I have also tried to create frameworks but thanks to Apple, I cannot create frameworks for iOS and have to create libraries and bundles and create a nightmare of paths from one to the other and to the project to make that sh!t works. So, I am done with frameworks/libraries on Xcode until Xcode is a decent IDE. So, I see I need something better to manage my source code. What I need is this (I never used GIT on Xcode. I have read Apple docs but I still have these points): does git locally on Xcode allows me to deal with assets or just code? Can I have the equivalent of a "framework" (code + assets) managed by git locally? Can an entire xcodeproj be managed as a unity? I mean, Suppose I have a xcodeproj created and want GIT to manage it. How do I enable git on a project that was created without it and start designating files for management. (I have enabled git on Xcode's preferences, but all source control menu is grayed out). Is git the best option? Do I have another? Remember that my main condition is that the files should stay on the local computer. Please save me (I am a bit dramatic today). Thanks.

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  • In R, how do you get the best fitting equation to a set of data?

    - by Matherion
    I'm not sure wether R can do this (I assume it can, but maybe that's just because I tend to assume that R can do anything :-)). What I need is to find the best fitting equation to describe a dataset. For example, if you have these points: df = data.frame(x = c(1, 5, 10, 25, 50, 100), y = c(100, 75, 50, 40, 30, 25)) How do you get the best fitting equation? I know that you can get the best fitting curve with: plot(loess(df$y ~ df$x)) But as I understood you can't extract the equation, see Loess Fit and Resulting Equation. When I try to build it myself (note, I'm not a mathematician, so this is probably not the ideal approach :-)), I end up with smth like: y.predicted = 12.71 + ( 95 / (( (1 + df$x) ^ .5 ) / 1.3)) Which kind of seems to approximate it - but I can't help to think that smth more elegant probably exists :-) I have the feeling that fitting a linear or polynomial model also wouldn't work, because the formula seems different from what those models generally use (i.e. this one seems to need divisions, powers, etc). For example, the approach in Fitting polynomial model to data in R gives pretty bad approximations. I remember from a long time ago that there exist languages (Matlab may be one of them?) that do this kind of stuff. Can R do this as well, or am I just at the wrong place? (Background info: basically, what we need to do is find an equation for determining numbers in the second column based on the numbers in the first column; but we decide the numbers ourselves. We have an idea of how we want the curve to look like, but we can adjust these numbers to an equation if we get a better fit. It's about the pricing for a product (a cheaper alternative to current expensive software for qualitative data analysis); the more 'project credits' you buy, the cheaper it should become. Rather than forcing people to buy a given number (i.e. 5 or 10 or 25), it would be nicer to have a formula so people can buy exactly what they need - but of course this requires a formula. We have an idea for some prices we think are ok, but now we need to translate this into an equation.

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  • What's the fastest lookup algorithm for a key, pair data structure (i.e, a map)?

    - by truncheon
    In the following example a std::map structure is filled with 26 values from A - Z (for key) and 0 – 26 for value. The time taken (on my system) to lookup the last entry (10000000 times) is roughly 250 ms for the vector, and 125 ms for the map. (I compiled using release mode, with O3 option turned on for g++ 4.4) But if for some odd reason I wanted better performance than the std::map, what data structures and functions would I need to consider using? I apologize if the answer seems obvious to you, but I haven't had much experience in the performance critical aspects of C++ programming. #include <ctime> #include <map> #include <vector> #include <iostream> struct mystruct { char key; int value; mystruct(char k = 0, int v = 0) : key(k), value(v) { } }; int find(const std::vector<mystruct>& ref, char key) { for (std::vector<mystruct>::const_iterator i = ref.begin(); i != ref.end(); ++i) if (i->key == key) return i->value; return -1; } int main() { std::map<char, int> mymap; std::vector<mystruct> myvec; for (int i = 'a'; i < 'a' + 26; ++i) { mymap[i] = i - 'a'; myvec.push_back(mystruct(i, i - 'a')); } int pre = clock(); for (int i = 0; i < 10000000; ++i) { find(myvec, 'z'); } std::cout << "linear scan: milli " << clock() - pre << "\n"; pre = clock(); for (int i = 0; i < 10000000; ++i) { mymap['z']; } std::cout << "map scan: milli " << clock() - pre << "\n"; return 0; }

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  • How do I stop and repair a RAID 5 array that has failed and has I/O pending?

    - by Ben Hymers
    The short version: I have a failed RAID 5 array which has a bunch of processes hung waiting on I/O operations on it; how can I recover from this? The long version: Yesterday I noticed Samba access was being very sporadic; accessing the server's shares from Windows would randomly lock up explorer completely after clicking on one or two directories. I assumed it was Windows being a pain and left it. Today the problem is the same, so I did a little digging; the first thing I noticed was that running ps aux | grep smbd gives a lot of lines like this: ben 969 0.0 0.2 96088 4128 ? D 18:21 0:00 smbd -F root 1708 0.0 0.2 93468 4748 ? Ss 18:44 0:00 smbd -F root 1711 0.0 0.0 93468 1364 ? S 18:44 0:00 smbd -F ben 3148 0.0 0.2 96052 4160 ? D Mar07 0:00 smbd -F ... There are a lot of processes stuck in the "D" state. Running ps aux | grep " D" shows up some other processes including my nightly backup script, all of which need to access the volume mounted on my RAID array at some point. After some googling, I found that it might be down to the RAID array failing, so I checked /proc/mdstat, which shows this: ben@jack:~$ cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] md0 : active raid5 sdb1[3](F) sdc1[1] sdd1[2] 2930271872 blocks level 5, 64k chunk, algorithm 2 [3/2] [_UU] unused devices: <none> And running mdadm --detail /dev/md0 gives this: ben@jack:~$ sudo mdadm --detail /dev/md0 /dev/md0: Version : 00.90 Creation Time : Sat Oct 31 20:53:10 2009 Raid Level : raid5 Array Size : 2930271872 (2794.53 GiB 3000.60 GB) Used Dev Size : 1465135936 (1397.26 GiB 1500.30 GB) Raid Devices : 3 Total Devices : 3 Preferred Minor : 0 Persistence : Superblock is persistent Update Time : Mon Mar 7 03:06:35 2011 State : active, degraded Active Devices : 2 Working Devices : 2 Failed Devices : 1 Spare Devices : 0 Layout : left-symmetric Chunk Size : 64K UUID : f114711a:c770de54:c8276759:b34deaa0 Events : 0.208245 Number Major Minor RaidDevice State 3 8 17 0 faulty spare rebuilding /dev/sdb1 1 8 33 1 active sync /dev/sdc1 2 8 49 2 active sync /dev/sdd1 I believe this says that sdb1 has failed, and so the array is running with two drives out of three 'up'. Some advice I found said to check /var/log/messages for notices of failures, and sure enough there are plenty: ben@jack:~$ grep sdb /var/log/messages ... Mar 7 03:06:35 jack kernel: [4525155.384937] md/raid:md0: read error NOT corrected!! (sector 400644912 on sdb1). Mar 7 03:06:35 jack kernel: [4525155.389686] md/raid:md0: read error not correctable (sector 400644920 on sdb1). Mar 7 03:06:35 jack kernel: [4525155.389686] md/raid:md0: read error not correctable (sector 400644928 on sdb1). Mar 7 03:06:35 jack kernel: [4525155.389688] md/raid:md0: read error not correctable (sector 400644936 on sdb1). Mar 7 03:06:56 jack kernel: [4525176.231603] sd 0:0:1:0: [sdb] Unhandled sense code Mar 7 03:06:56 jack kernel: [4525176.231605] sd 0:0:1:0: [sdb] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE Mar 7 03:06:56 jack kernel: [4525176.231608] sd 0:0:1:0: [sdb] Sense Key : Medium Error [current] [descriptor] Mar 7 03:06:56 jack kernel: [4525176.231623] sd 0:0:1:0: [sdb] Add. Sense: Unrecovered read error - auto reallocate failed Mar 7 03:06:56 jack kernel: [4525176.231627] sd 0:0:1:0: [sdb] CDB: Read(10): 28 00 17 e1 5f bf 00 01 00 00 To me it is clear that device sdb has failed, and I need to stop the array, shutdown, replace it, reboot, then repair the array, bring it back up and mount the filesystem. I cannot hot-swap a replacement drive in, and don't want to leave the array running in a degraded state. I believe I am supposed to unmount the filesystem before stopping the array, but that is failing, and that is where I'm stuck now: ben@jack:~$ sudo umount /storage umount: /storage: device is busy. (In some cases useful info about processes that use the device is found by lsof(8) or fuser(1)) It is indeed busy; there are some 30 or 40 processes waiting on I/O. What should I do? Should I kill all these processes and try again? Is that a wise move when they are 'uninterruptable'? What would happen if I tried to reboot? Please let me know what you think I should do. And please ask if you need any extra information to diagnose the problem or to help!

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