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  • Efficient way to calculate "vision cones" on 2D tile map?

    - by OverMachoGrande
    I'm trying to calculate which tiles a particular unit can "see" if facing a certain direction on a tile map (within a certain range and angle of facing). The easiest way would be to draw a certain number of tiles outward and raycast to each tile. However, I'm hoping for something slightly more efficient. A picture says a thousand words: The red dot is the unit (who's facing upwards). My goal is to calculate the yellow tiles. The green blocks are walls (walls are between tiles, and it's easy to check if you can pass between two tiles). The blue line represents something like the "raycasting" method I was talking about, but I'd rather not have to do this. EDIT: Units can only be facing north/south/east/west (0, 90, 180, or 270 degrees) and FoV is always 90 degrees. Should simplify some calculations. I'm thinking there's some sort of recursive-ish/stack-based/queue-based algorithm, but I can't quite figure it out. Thanks!

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  • Nouveau forum d'entraide Qualimétrie : posez vos questions sur les pratiques d'analyse de code et d'

    Bonjour, Le forum Qualimétrie se destine à toutes vos questions concernant les pratiques et outils touchant à la qualité du code et de l'architecture du logiciel. Il se destine également à accueillir vos questions sur l'intégration et l'utilisation (ex. Plugin Maven) des outils de qualimétrie dans les outils de build. N'hésitez pas, avant de poser votre question, à consulter la documentation de l'outil concerné, ainsi que les ressources à votre disposition. Pour toute contribution sur le sujet, vous pouvez contacter l'équipe bénévole par mail via conception [at] redaction [dash] developpez [dot] com...

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  • Hiding images in folder without renaming or moving the files

    - by Marcus
    I'm dual booting Ubuntu with Windows and I have all my music on a separate harddrive. In Windows the album art is hidden by default but when I access the folder in Ubuntu there is two album artwork files for every mp3, one small and one large. I would like to hide those images without having to rename them with a dot before or moving them to some other folder becuase then the album artwork would dissapear in Windows. Is there a way to make a .hidden file which hides all images or any other way which hides all images in nautilus?

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  • MVC 2 Breaks my Charts?

    - by GeekAgilistMercenary
    I wonder if anyone has had issues with running MSCharts with MVC 2?  I have tried a couple of different issues, but still have not got them to render correctly.  In the end I always end up with broken image links.  Has anyone seen this? I have no errors displaying in my MVC 2 Application build or anything, nothing specific that leads me to any explanation.  If anyone has any ideas, please leave a comment or shoot me an e-mail; adronhall at gmail dot com.  I would greatly appreciate any insight you MSChart Elite may have.  : )

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  • Apress "Introducing Visual C# 2010" - ISBN 978-1-4302-3171-4 - Conclusion

    - by TATWORTH
    After having spent several weeks reading this book (1230 pages before the index!), I can thoroughly recommend this book as a practical introduction to Visual C# 2010 both to people learning C# and to experianced C# users. It introduces C# through practical examples then gives a good introduction to the Dot Net framework. After dealing with Data Access, it gives a brief introduction to variousUI technologies. The final section deals with advanced topics including a thoroughly practical intruction to windows services. There are copious coding examples and useful tips. Many chapters begin with a quick problem solver solution reference. In short "Introducing Visual C# 2010" in the words of the sub title, is an excellent start to your C# journey with an expert by your side leading by example.

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  • What are the steps taken by this GLSL code?

    - by user827992
    1 void main(void) 2 { 3 vec2 pos = mod(gl_FragCoord.xy, vec2(50.0)) - vec2(25.0); 4 float dist_squared = dot(pos, pos); 5 6 gl_FragColor = (dist_squared < 400.0) 7 ? vec4(.90, .90, .90, 1.0) 8 : vec4(.20, .20, .40, 1.0); 9 } taken from http://people.freedesktop.org/~idr/OpenGL_tutorials/03-fragment-intro.html Now, this looks really trivial and simple, but my problem is with the mod function. This function is taking 2 vec2 as inputs but is supposed to take just 2 atomic arguments according to the official documentation, also this function makes an implicit use of the floor function that only accepts, again, 1 atomic argument. Can someone explain this to me step by step and point out what I'm not getting here? It's some kind of OpenGL trick? OpenGL Math trick? in the GLSL docs i always find and explicit reference to the type accepted by the function and vec2 it's not there.

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  • APress Deal of the Day - 13/Apr/2012 - Pro WPF and Silverlight MVVM

    - by TATWORTH
    The APress $10 deal of the day for today is "Applied WPF 4 in Context" (http://www.apress.com/9781430234708) starts with a simple introduction to WPF and then shows a complete WPF application from sketch to completed code. This APress web site states "This book can be used by a junior developer to learn WPF and understand how to architect a layered application, and it can also be used by a senior developer as a reference for developing scalable WPF applications. " - this summerises the book very effectively as it is indeed an excellent book both for learning WPF and as a reference for development. I recommend it to all Dot Net development teams.

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  • APress Deal of the Day 15/Jan/2011 - Windows Mobile Game Development: Building games for the Windows Phone and other mobile devices

    - by TATWORTH
    Todays Apress $10 deal of the the day is: Windows Mobile Game Development: Building games for the Windows Phone and other mobile devices This book will provide you with a comprehensive guide to developing games for both the Windows Mobile platform and the Windows Phone using the industry standard programming languages C# and VB.NET. $49.99 | Published Apr 2010 | The book dates from the VS2005/VS2008 era but should still be useful to VS2010 developers. Given that such games development can now be done within Visual Studio. Whilst these devices use the Compact Framework instead of the standard Dot Net Framework, it is still a familiar envirnment. This book should be of benefit not just to games developers but to anyone with an interest in development for mobile phones.

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  • Check if the vector is behind another or maybe opposite directions?

    - by Gilson
    I'm doing a network game and on the client side, i interpolate the client position with the server sent extrapolated position. The client has its own physics simulation wich is corrected by the server in steps. The problem is when it laggs and i 'kick' the ball, the server gets a delayed message and sends me the position backwards of the client position wich makes the ball goes back and forth. I want to ignore those and maybe compensate that on the server, not sure though. The problem is the clock difference on those case are 0.07ms or 0.10 ms wich isn't that high to ignore the message i guess. When i get the server position, i extrapolate with the clock interval * serverBallVelocity Can i check if my new ball server position is behind my actual ball vector position? I tried to use the dot product after normalized the two vectors to check if they are opposite but it ain't working properly. Any suggestions on checking that?

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  • 2012 JCP Awards

    - by Tori Wieldt
    Nominations are now open for the 2012 JCP Awards. Submit nominations to PMO at JCP dot ORG or use this form.  The Java Community Process (JCP) program celebrates success. Members of the community nominate worthy participants, Spec Leads, and Java Specification Requests (JSRs) in order to cheer on the hard work and creativity that produces ground-breaking results for the community and industry in the Java Standard Edition (SE), Java Enterprise Edition (EE), or Java Micro Edition (ME) platforms. The community gets together every year at the JavaOne conference to applaud in person the winners of three awards: JCP Member/Participant of the Year, Outstanding Spec Lead, and Most Significant JSR. This year’s unveiling will occur Tuesday evening, 2 October, at the Annual JCP Community Party held in San Francisco during JavaOne. Nominations close on 16 July 2012. More details are on the JCP blog.

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  • Instead of the specified Texture, black circles on a green background are getting rendered. Why?

    - by vinzBad
    I'm trying to render a Texture via OpenGL. But instead of the texture black circles on a green background are rendered. (They scale, depending what the rotation of the texture is) Example: The texture I'm trying to render is the following: This is the code I use to render the texture, it's located in my Sprite-class. public void Render() { Matrix4 matrix = Matrix4.CreateTranslation(-OriginX, -OriginY, 0) * Matrix4.CreateRotationZ(Rotation) * Matrix4.CreateTranslation(X, Y, 0); Vector2[] corners = { new Vector2(0,0), //top left new Vector2(Width ,0),//top right new Vector2(Width,Height),//bottom rigth new Vector2(0,Height)//bottom left }; //copy the corners to the uv coordinates Vector2[] uv = corners.ToArray<Vector2>(); //transform the coordinates for (int i = 0; i < 4; i++) corners[i] = new Vector2(Vector3.Transform(new Vector3(corners[i]), matrix)); //GL.Color3(TintColor); GL.BindTexture(TextureTarget.Texture2D, _ID); GL.Begin(BeginMode.Quads); { for (int i = 0; i < 4; i++) { GL.TexCoord2(uv[i]); GL.Vertex3(corners[i].X, corners[i].Y, _layerDepth); } } GL.End(); if (EnableDebugDraw) { GL.Color3(Color.Violet); GL.PointSize(3); GL.Begin(BeginMode.Points); { for (int i = 0; i < 4; i++) GL.Vertex2(corners[i]); } GL.End(); GL.Color3(Color.Green); GL.Begin(BeginMode.Points); GL.Vertex2(X, Y); GL.End(); } } This is how I setup OpenGL. public static void SetupGL() { GL.Enable(EnableCap.AlphaTest); GL.AlphaFunc(AlphaFunction.Greater, 0.1f); GL.Enable(EnableCap.Texture2D); GL.Hint(HintTarget.PerspectiveCorrectionHint, HintMode.Nicest); } With this function I load the texture: public static uint LoadTexture(string path) { uint id; GL.GenTextures(1, out id); GL.BindTexture(TextureTarget.Texture2D, id); Bitmap bitmap = new Bitmap(path); BitmapData data = bitmap.LockBits(new System.Drawing.Rectangle(0, 0, bitmap.Width, bitmap.Height), ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format32bppArgb); GL.TexImage2D(TextureTarget.Texture2D, 0, PixelInternalFormat.Rgba, data.Width, data.Height, 0, OpenTK.Graphics.OpenGL.PixelFormat.Bgra, PixelType.UnsignedByte, data.Scan0); bitmap.UnlockBits(data); GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, (int)TextureMinFilter.Linear); GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, (int)TextureMagFilter.Linear); return id; } And here I call Sprite.Render() protected override void OnRenderFrame(FrameEventArgs e) { GL.ClearColor(Color.MidnightBlue); GL.Clear(ClearBufferMask.ColorBufferBit); _sprite.Render(); SwapBuffers(); base.OnRenderFrame(e); } As I stole this code from the Textures-Example from OpenTK, I don't understand why this doesn't work.

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  • After one has made many grid based puzzles how does one make then into a PDF ready for printing

    - by alan ross
    After one has generated many grid based puzzles like sudoku, kakuro or even plain crosswords and now one has to print them in a book. How does one make a pdf (book file) from them automatically. To explain the question better. One has the puzzle ready in computer format like ..35.6.89 for all nine rows. The dot being the empty cell. How does one convert then to a picture on a PDF page complete with box, automatically without doing them individually and then print a book from the pdf file. As can be seen there are other things also printed on the page all this is done automatically.

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  • variable declaration in javascript [migrated]

    - by ShaggyInjun
    I have been doing something like this for a while and I have never seen any errors. But, unfortunately, I have never been able to explain why this works. The first line creates a variable which points to a function. The second line just adds func2 to func1 separated by a dot and defines a function. If I add a var in front of func1.func2 then I see a compilation error. func1.func2 = function(){}; Error SyntaxError: missing ; before statement var func1.func2 = function(){}; What type was func1 on first line 1 and what did it become on line 2. var func1 = function(){}; func1.func2 = function(){}; Thanks Venkat

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  • Get all triangles that are < N dist from you?

    - by CyanPrime
    Does anyone know of a way I could add a radius to this code for p? Like basically saying "this is true if the triangle is < N dist from the point" public boolean isPointInTriangle( Vector3f p, Vector3f a, Vector3f b, Vector3f c ) { return ( pointsAreOnSameSide(p, a, b, c) && pointsAreOnSameSide(p, b, a, c) && pointsAreOnSameSide(p, c, a, b) ); } public boolean pointsAreOnSameSide( Vector3f p1, Vector3f p2, Vector3f a, Vector3f b ) { Vector3f diffba = new Vector3f(0,0,0); Vector3f.sub( b, a, diffba ); Vector3f diffp1a = new Vector3f(0,0,0); Vector3f.sub( p1, a, diffp1a ); Vector3f diffp2a = new Vector3f(0,0,0); Vector3f.sub( p2, a, diffp2a ); Vector3f cross1 = Vector3f.cross(diffba, diffp1a); Vector3f cross2 = Vector3f.cross(diffba, diffp2a); return ( Vector3f.dot( cross1, cross2 ) >= 0 ); }

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  • Happy Birthday LearnVisualStudio.NET?

    - by TATWORTH
    Back in 2003, I made the changeover to Dot Net with the help of LearnViusal Studio.NET. They provide an excellent learning resource. I commend membership to you. This week only, you can get started for as little as $48.97 for a 1 Year Subscription! Save 30% at LearnVisualStudio.NET http://www.learnvisualstudio.net?awt_l=BN5TZ&awt_m=JaSOlFqKSr1QwB You can also get a Lifetime membership for only $139.97! That's over $59 in savings! A lifetime membership will grant you access to every video on the site and every video we ever create for LearnVisualStudio.NET without giving us another dime! This is a great chance to access over 900 tutorials to help you learn C#, VB, ASP NET and more. Get started today! http://www.learnvisualstudio.net?awt_l=BN5TZ&awt_m=JaSOlFqKSr1QwB

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  • Visual Studio: Add Item / Add as link rather than just Add

    - by Pete d'Oronzio
    I'm new to visual studio, coming from Delphi. I have a directory tree full of .cs files (root is \Common). I also have a directory tree full of Applications (root is \Applications) Finally, I've got a tree full of Assemblies (root is \Assemblies) I'd like to keep my .cs files in the Common tree and all the environment voodoo (solutions, projects, settings, metadata, debug data, bin, etc.) in the Assmblies tree. So, for a simple example, I've got an assembly called PdMagic.Common.Math.dll. The Solution and project is located in \Assemblies\Common\Math. All of its source (.cs) files are in \Common\Math. (matrix.cs, trig.cs, mathtypes.cs, mathfuncs.cs, stats.cs, etc.) When I use Add Existing Item to add matrix.cs to my project, a copy of it is added to the \Assemblies\Common\Math folder. I just want to reference it. I don't want multiple copies laying around. I've tried Add Existing Item, and used the drop down to "Add link" rather than just "Add", and that seems to do what I want. Question: What is the "best practice" for this sort of thing? Do most people just put those .cs files all in the same folder as the project? Why isn't "Add link" the default? Thanks!

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  • WPF TextBox.SelectAll () doesn't work

    - by Zoliq
    Hi! I have used the following template in my project: <DataTemplate x:Key="textBoxDataTemplate"> <TextBox Name="textBox" ToolTip="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors)[0].ErrorContent}" Tag="{Binding}" PreviewKeyDown="cellValueTextBoxKeyDown"> <TextBox.Text> <MultiBinding Converter="{StaticResource intToStringMultiConverter}"> <Binding Path="CellValue" Mode="TwoWay"> <Binding.ValidationRules> <y:MatrixCellValueRule MaxValue="200" /> </Binding.ValidationRules> </Binding> <Binding RelativeSource="{RelativeSource FindAncestor, AncestorType={x:Type y:MatrixGrid}}" Path="Tag" Mode="OneWay" /> </MultiBinding> </TextBox.Text> </TextBox> </DataTemplate> I used this template to create an editable matrix for the user. The user is able to navigate from cell to cell within the matrix and I would like to highlight the data in the selected textbox but it doesn't work. I called TextBox.Focus () and TextBox.SelectAll () to achieve the effect but nothing. The Focus () works but the text never gets highlighted. Any help is welcome and appreciated.

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  • A simple augmented reality application in C#

    - by Ian
    Hi All, I would like to start a personal project that will give me a lot of new concept to learn and understand. After some thought, I figured that an Augmented Reality related project will be the most beneficial for me because of the following reasons: I haven't tried interfacing a program with a live video/camera feed I haven't done any "image processing" project I haven't done any "graphics rendering" ever With that said, you can assume that I will totally suck at AR. So I'm here to ask for some advice regarding the best way to go through this. st milestone project that I am thinking of is to take a cheap webcam and read some Data Matrix using C#. nd milestone project will render some text-overlay on the feed when presented with a certain Data Matrix. rd milestone project will actually render some 3D shapes. I've searched all-around and found some nice yet advanced materials for AR: http://sites.google.com/site/augmentedrealitytestingsite/ http://soldeveloper.com/ http://www.mperfect.net/wpfAugReal/ So I came here to ask the following: Do you think my milestone is reasonable given my "deficiencies"? In order to start Milestone 1, can you give some materials that I can study? I prefer online materials. Thanks!

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  • Transform OpenGL coordinates to lower UIView coordinates

    - by John Qualis
    Hi, I am new to OpenGL over iPhone. I am developing an iPhone app similar to a barcode reader but with an extra OpenGL layer. The bottommost layer is UIImagePickerController, then I use UIView on top and draw a rectangle at certain co-ordinates on the iphone screen. So far everything is OK. Then I am trying to draw an OpenGL 3-D model in that rectangle. I am able to load a 3-D model in the iPhone based on this code here - http://iphonedevelopment.blogspot.com/2008/12/start-of-wavefront-obj-file-loader.html I am not able to transform the co-ordinates of the rectangle into OpenGL co-ordinates. Appreciate any help. Do I need to use a matrix to translate the currentPosition of the 3-D model so it is drawn within myRect? The code is given below.. Appreciate any help/pointers in this regards. John (void)drawView:(GLView*)view { static GLfloat rotation = 0.0; glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity(); glColor4f(0.0, 0.5, 1.0, 1.0); // The coordinates of the rectangle are myRect.x, // myRect.y, myRect.width, myRect.height // Do I need a transform matrix here? //glOrthof(-160.0f, 160.0f, -240.0f, 240.0f, -1.0f, 1.0f); [plane drawSelf]; .... } -(void)setupView:(GLView*)view { const GLfloat zNear = 0.01, zFar = 1000.0, fieldOfView = 45.0; GLfloat size; glEnable(GL_DEPTH_TEST); glMatrixMode(GL_PROJECTION); //glMatrixMode(GL_MODELVIEW); size = zNear * tanf(DEGREES_TO_RADIANS(fieldOfView) / 2.0); CGRect rect = view.bounds; glFrustumf(-size, size, -size / (rect.size.width / rect.size.height), size / (rect.size.width / rect.size.height), zNear, zFar); glViewport(0, 0, rect.size.width, rect.size.height); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glClearColor(0.0f, 0.0f, 0.0f, 0.0f); }

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  • Pixel Perfect Collision Detection in HTML5 Canvas

    - by Armin Ronacher
    Hi, I want to check a collision between two Sprites in HTML5 canvas. So for the sake of the discussion, let's assume that both sprites are IMG objects and a collision means that the alpha channel is not 0. Now both of these sprites can have a rotation around the object's center but no other transformation in case this makes this any easier. Now the obvious solution I came up with would be this: calculate the transformation matrix for both figure out a rough estimation of the area where the code should test (like offset of both + calculated extra space for the rotation) for all the pixels in the intersecting rectangle, transform the coordinate and test the image at the calculated position (rounded to nearest neighbor) for the alpha channel. Then abort on first hit. The problem I see with that is that a) there are no matrix classes in JavaScript which means I have to do that in JavaScript which could be quite slow, I have to test for collisions every frame which makes this pretty expensive. Furthermore I have to replicate something I already have to do on drawing (or what canvas does for me, setting up the matrices). I wonder if I'm missing anything here and if there is an easier solution for collision detection.

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  • Arrrg! MovieClip object refuses to moved in any rational way in as3?

    - by Aaron H.
    I have a MovieClip object, which is exported for actionscript (AS3) in an .swc file. When I place an instance of the clip on the stage without any modifications, it appears in the upper left corner, about half off stage (i.e. only the lower right quadrant of the object is visible). I understand that this is because the clip has a registration point which is not the upper left corner. If you call getBounds() on the movieclip you can get the bounds of the clip (presumably from the "point" that it's aligned on) which looks something like (left: -303, top: -100, right: 303, bottom: 100), you can subtract the left and top values from the clip x and y: clip.x -= bounds.left; clip.y -= bounds.top; This seems to properly align the clip fully on stage with the top left of the clip squarely in the corner of the stage. But! Following that logic doesn't seem to work when aligning it on the center of the stage! clip.x = (stage.stageWidth / 2); etc... This creates the crazy parallel universe where the clip is now down in the lower right corner of the stage. The only clue I have is that looking at: clip.transform.matrix and clip.transform.concatenatedMatrix matrix has a tx value of 748 (half of stage height) ty value of 426 (Half of stage height) concatenatedMatrix has a tx value of 1699.5 and ty value of 967.75 That's also obviously where the movieclip is getting positioned, but why? Where is this additional translation coming from?

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  • Accurate least-squares fit algorithm needed

    - by ggkmath
    I've experimented with the two ways of implementing a least-squares fit (LSF) algorithm shown here. The first code is simply the textbook approach, as described by Wolfram's page on LSF. The second code re-arranges the equation to minimize machine errors. Both codes produce similar results for my data. I compared these results with Matlab's p=polyfit(x,y,1) function, using correlation coefficients to measure the "goodness" of fit and compare each of the 3 routines. I observed that while all 3 methods produced good results, at least for my data, Matlab's routine had the best fit (the other 2 routines had similar results to each other). Matlab's p=polyfit(x,y,1) function uses a Vandermonde matrix, V (n x 2 matrix) and QR factorization to solve the least-squares problem. In Matlab code, it looks like: V = [x1,1; x2,1; x3,1; ... xn,1] % this line is pseudo-code [Q,R] = qr(V,0); p = R\(Q'*y); % performs same as p = V\y I'm not a mathematician, so I don't understand why it would be more accurate. Although the difference is slight, in my case I need to obtain the slope from the LSF and multiply it by a large number, so any improvement in accuracy shows up in my results. For reasons I can't get into, I cannot use Matlab's routine in my work. So, I'm wondering if anyone has a more accurate equation-based approach recommendation I could use that is an improvement over the above two approaches, in terms of rounding errors/machine accuracy/etc. Any comments appreciated! thanks in advance.

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  • help in the Donalds B. Johnson's algorithm, i cannot understand the pseudo code

    - by Pitelk
    Hi , does anyone know the Donald B. Johnson's algorithm which enumarates all the elementary circuits (cycles) in a Directed graph? link text I have the paper he had published in 1975 but I cannot understand the pseudo-code. My goal is to implement this algorithm in java. Some questions i have is for example what is the matrix Ak it refers to. In the pseudo code mentions that Ak:=adjacency structure of strong component K with least vertex in subgraph of G induced by {s,s+1,....n}; Does that mean i have to implement another algorithm that finds the Ak matrix? Another question is what the following means? begin logical f; Does also the line "logical procedure CIRCUIT (integer value v);" means that the circuit procedure returns a logical variable. In the pseudo code also has the line "CIRCUIT := f;" . Does this mean? It would be great if someone could translate this 1970's pseudocode to a more modern type of pseudo code so i can understand it in case you are interested to help but you cannot find the paper please email me at [email protected] and i will send you the paper. Thanks in advance

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  • Fitting Gaussian KDE in numpy/scipy in Python

    - by user248237
    I am fitting a Gaussian kernel density estimator to a variable that is the difference of two vectors, called "diff", as follows: gaussian_kde_covfact(diff, smoothing_param) -- where gaussian_kde_covfact is defined as: class gaussian_kde_covfact(stats.gaussian_kde): def __init__(self, dataset, covfact = 'scotts'): self.covfact = covfact scipy.stats.gaussian_kde.__init__(self, dataset) def _compute_covariance_(self): '''not used''' self.inv_cov = np.linalg.inv(self.covariance) self._norm_factor = sqrt(np.linalg.det(2*np.pi*self.covariance)) * self.n def covariance_factor(self): if self.covfact in ['sc', 'scotts']: return self.scotts_factor() if self.covfact in ['si', 'silverman']: return self.silverman_factor() elif self.covfact: return float(self.covfact) else: raise ValueError, \ 'covariance factor has to be scotts, silverman or a number' def reset_covfact(self, covfact): self.covfact = covfact self.covariance_factor() self._compute_covariance() This works, but there is an edge case where the diff is a vector of all 0s. In that case, I get the error: File "/srv/pkg/python/python-packages/python26/scipy/scipy-0.7.1/lib/python2.6/site-packages/scipy/stats/kde.py", line 334, in _compute_covariance self.inv_cov = linalg.inv(self.covariance) File "/srv/pkg/python/python-packages/python26/scipy/scipy-0.7.1/lib/python2.6/site-packages/scipy/linalg/basic.py", line 382, in inv if info>0: raise LinAlgError, "singular matrix" numpy.linalg.linalg.LinAlgError: singular matrix What's a way to get around this? In this case, I'd like it to return a density that's essentially peaked completely at a difference of 0, with no mass everywhere else. thanks.

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  • Suggest a good method with least lookup time complexity

    - by Amrish
    I have a structure which has 3 identifier fields and one value field. I have a list of these objects. To give an analogy, the identifier fields are like the primary keys to the object. These 3 fields uniquely identify an object. Class { int a1; int a2; int a3; int value; }; I would be having a list of say 1000 object of this datatype. I need to check for specific values of these identity key values by passing values of a1, a2 and a3 to a lookup function which would check if any object with those specific values of a1, a2 and a3 is present and returns that value. What is the most effective way to implement this to achieve a best lookup time? One solution I could think of is to have a 3 dimensional matrix of length say 1000 and populate the value in it. This has a lookup time of O(1). But the disadvantages are. 1. I need to know the length of array. 2. For higher identity fields (say 20), then I will need a 20 dimension matrix which would be an overkill on the memory. For my actual implementation, I have 23 identity fields. Can you suggest a good way to store this data which would give me the best look up time?

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