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  • Mapping Hilbert values to 3D points

    - by Alexander Gladysh
    I have a set of Hilbert values (length from the start of the Hilbert curve to the given point). What is the best way to convert these values to 3D points? Original Hilbert curve was not in 3D, so I guess I have to pick by myself the Hilbert curve rank I need. I do have total curve length though (that is, the maximum value in the set). Perhaps there is an existing implementation? Some library that would allow me to work with Hilbert curve / values? Language does not matter much.

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  • Calculate the Hilbert value of a point for use in a Hilbert R-Tree?

    - by wrt
    I have an application where a Hilbert R-Tree (wikipedia) (citeseer) would seem to be an appropriate data structure. Specifically, it requires reasonably fast spatial queries over a data set that will experience a lot of updates. However, as far as I can see, none of the descriptions of the algorithms for this data structure even mention how to actually calculate the requisite Hilbert Value; which is the distance along a Hilbert Curve to the point. So any suggestions for how to go about calculating this?

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  • Spring 3 learning curve

    - by Lucian Enache
    I'm coming from a Struts background and I was considering learning the Spring framework. How long would it usually take to get familiarity with Spring Core and Spring MVC modules, keeping in mind that I come from a Struts 1 background ? Beside those two modules are there any other modules that I should focus on ? I know that the time is relative given that everyone has a different learning curve.

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  • How can I boost my C# learning curve?

    - by MSU
    I have been learning programming, mostly C# and .net stuff. And I have target to become a fulltime .NET developer. But I am feeling that learning Graph is very slow, I have been learning C# programming, doing some coding everyday, but how I can learn very fast and increase my skills rapidly? I know there should be a balance of coding and reading, as without reading I can't code and without coding I can't increase my skills. SO, I am requesting here suggesting from experts on how I bring more pace to my learning curve? I intend to give 4-6 hours daily for this and on weekends 10+ hours.

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  • Linux Learning curve for a 'Lifetime' windows user [closed]

    - by gary
    I am using windows for almost 8-10 years and have never worked on linux. Mostly i used to work in VB, VC++ MFC and little bit of .NET(C# and VB) so i didn't bother about Linux. But now when i got an opportunity to work with linux i dont want to miss it, here are my questions : Where can i find useful resources for Linux newbies? Which books/Tutorials will you suggest to start? Which distro shall i use? What was your experience while moving from Windows to Linux?

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  • ASP.NET and C# learning curve [closed]

    - by Mashael
    My friend wants to become a web developer. However, he doesn't know how to start if he is going to become ASP.NET developer. He found a book which is titled ' Beginning ASP.NET 4: in C# and VB (Wrox Programmer to Programmer) by Imar Spaanjaars' but he is not sure if this will be right start or not because he has know knowledge in OOP programming and whether he has to learn C# first and read such book or is it OK to start with such that book assuming that the book will teach some fundamentals in C#!

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  • Implementing a hilbert map of the internet

    - by Martin
    In the XKCD comic 195 a design for a map of the internet address space is suggested using a hilbert curve so that items from a similar IPs will be clustered together. Given an IP address, how would I calculate the 2D coordinates (in the range zero to one) that this IP is located on such a map?

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  • Finding the Formula for a Curve

    - by Mystagogue
    Is there a program that will take "response curve" values from me, and provide a formula that approximates the response curve? It would be cool if such a program would take a numeric "percent correct" (perhaps with a standard deviation) so that it returns simplified formulas when laxity is permissable, and more precise (viz. complex) formulas when the curve needs to be approximated closely. My interest is to play with the response curve values and "laxity" factor, until such a tool spits out a curve-fit formula simple enough that I know it will be high performance during machine computations.

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  • Quaddratic Bezier Curve: Calculate Tangent

    - by stefan.at.wpf
    Hello, I have have a quadratic bezier curve and I want to calculate the slope of the tangent in a given point. For example, let it be the middlepoint of the quadratic bezier curve, therefore t=0.5 (please see the link below for a picture of this). I've calculated the first derivation of the formula for the quadratic bezier curve, however I get 400 as value for the slope, though it should be 0. Maybe I'm using the first derivation in a wrong way? I know I could also calculate the tangents using trigonometric functions, however I'd like to do it using the first derivation, shouldn't this be possible? Thanks for any hint! For clarification / please note: I'm interested in a general way to get the slope in a arbitrary given point on a quadratic bezier curve, not only to get the tangent in the start- and end point. A picture of my problem including the text above: http://cid-0432ee4cfe9c26a0.skydrive.live.com/self.aspx/%c3%96ffentlich/Quadratic%20Bezier%20Curve.pdf Thank you very much for any hint!

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  • Reverse engineering a bezier curve

    - by Martin
    Given a few sample points on a bézier curve, is it possible to work out the set of possible parameters of the curve? In my specific application there is a limited set of endpoints the curve may have, so I want to generate the set of possible curves, enumerate all of them and pick out all the ones which may end on a valid end point.

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  • Quadratic Bezier Curve: Calculate Tangent

    - by stefan.at.wpf
    I have a quadratic bezier curve and I want to calculate the slope of the tangent in a given point. For example, let it be the middlepoint of the quadratic bezier curve, therefore t=0.5 (please see the link below for a picture of this). I've calculated the first derivative of the formula for the quadratic bezier curve; however I get 400 as value for the slope, though it should be 0. Maybe I'm using the first derivative in a wrong way? I know I could also calculate the tangents using trigonometric functions; however I'd like to do it using the first derivative, shouldn't this be possible? Thanks for any hint! For clarification / please note: I'm interested in a general way to get the slope in a arbitrary given point on a quadratic bezier curve, not only to get the tangent in the start- and end point. A picture of my problem including the text above: http://cid-0432ee4cfe9c26a0.skydrive.live.com/self.aspx/%c3%96ffentlich/Quadratic%20Bezier%20Curve.pdf Thank you very much for any hint!

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  • Tools for visualizing and implementing elliptic curve cryptography

    - by LL
    I need to create a program which will show how elliptic curve cryptography works. I was considering using Java Swing to create the GUI, but the main problem is what tool to use to plot the elliptic curve itself, and how to integrate that with Java Swing. I would like the plot to be included in the user interface and also allow changes to be made to it. Can you suggest any tools that would help with this?

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  • How to calculate point along a curve?

    - by Nicros
    I am writing a custom animation for wpf and as a non math guy I have a couple questions... If I am given two Point3D's, the From and To, and assuming the origin is at 0,0,0 how do I calculate a curve between the two points? And once I have the curve 'plotted' and I know its length (how to do that too?) how can I calculate the x,y,z coords at some given distance along the line? Thanks!

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  • How can I decrease my C# learning curve? [closed]

    - by MSU
    I have been learning programming, mostly C# and .net stuff. And I have target to become a fulltime .NET developer. But I am feeling that learning Graph is very slow, I have been learning C# programming, doing some coding everyday, but how I can learn very fast and increase my skills rapidly? I know there should be a balance of coding and reading, as without reading I can't code and without coding I can't increase my skills. SO, I am requesting here suggesting from experts on how I bring more pace to my learning curve? I intend to give 4-6 hours daily for this and on weekends 10+ hours.

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  • How can I lower my C# learning curve? [closed]

    - by MSU
    I have been learning programming, mostly C# and .net stuff. And I have target to become a fulltime .NET developer. But I am feeling that learning Graph is very slow, I have been learning C# programming, doing some coding everyday, but how I can learn very fast and increase my skills rapidly? I know there should be a balance of coding and reading, as without reading I can't code and without coding I can't increase my skills. SO, I am requesting here suggesting from experts on how I bring more pace to my learning curve? I intend to give 4-6 hours daily for this and on weekends 10+ hours.

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  • Modifying and Manipulating a interactive bezier curve

    - by rachel
    This is a homework question and I'm having a lot of trouble with it - I've managed to do some of it but still cant finish it - can i Please get some help. Q1. Bezier Curves The following example allows you to interactively control a bezier curve by dragging the control points Cubic.java Replace the call to draw the cubic shape (big.draw(cubic)), by your own function to draw a bezier by the recursive split method. Finally, add the ability to create a longer Bezier curve by adding more control points to create a second curve. Cubic.java import java.awt.*; import javax.swing.*; import java.awt.event.*; import java.applet.Applet; import java.awt.geom.*; import java.awt.image.BufferedImage; public class Cubic extends JApplet{ static protected JLabel label; CubicPanel cubicPanel; public void init(){ //Initialize the layout. getContentPane().setLayout(new BorderLayout()); cubicPanel = new CubicPanel(); cubicPanel.setBackground(Color.white); getContentPane().add(cubicPanel); label = new JLabel("Drag the points to adjust the curve."); getContentPane().add("South", label); } public static void main(String s[]) { JFrame f = new JFrame("Cubic"); f.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) {System.exit(0);} }); JApplet applet = new Cubic(); f.getContentPane().add(applet, BorderLayout.CENTER); applet.init(); f.setSize(new Dimension(350,250)); f.setVisible(true); } } class CubicPanel extends JPanel implements MouseListener, MouseMotionListener{ BufferedImage bi; Graphics2D big; int x, y; Rectangle area, startpt, endpt, onept, twopt, rect; CubicCurve2D.Double cubic = new CubicCurve2D.Double(); Point2D.Double start, end, one, two, point; boolean firstTime = true; boolean pressOut = false; public CubicPanel(){ setBackground(Color.white); addMouseMotionListener(this); addMouseListener(this); start = new Point2D.Double(); one = new Point2D.Double(); two = new Point2D.Double(); end = new Point2D.Double(); cubic.setCurve(start, one, two, end); startpt = new Rectangle(0, 0, 8, 8); endpt = new Rectangle(0, 0, 8, 8); onept = new Rectangle(0, 0, 8, 8); twopt = new Rectangle(0, 0, 8, 8); } public void mousePressed(MouseEvent e){ x = e.getX(); y = e.getY(); if(startpt.contains(x, y)){ rect = startpt; point = start; x = startpt.x - e.getX(); y = startpt.y - e.getY(); updateLocation(e); } else if(endpt.contains(x, y)){ rect = endpt; point = end; x = endpt.x - e.getX(); y = endpt.y - e.getY(); updateLocation(e); } else if(onept.contains(x, y)){ rect = onept; point = one; x = onept.x - e.getX(); y = onept.y - e.getY(); updateLocation(e); } else if(twopt.contains(x, y)){ rect = twopt; point = two; x = twopt.x - e.getX(); y = twopt.y - e.getY(); updateLocation(e); } else { pressOut = true; } } public void mouseDragged(MouseEvent e){ if(!pressOut) { updateLocation(e); } } public void mouseReleased(MouseEvent e){ if(startpt.contains(e.getX(), e.getY())){ rect = startpt; point = start; updateLocation(e); } else if(endpt.contains(e.getX(), e.getY())){ rect = endpt; point = end; updateLocation(e); } else if(onept.contains(e.getX(), e.getY())){ rect = onept; point = one; updateLocation(e); } else if(twopt.contains(e.getX(), e.getY())){ rect = twopt; point = two; updateLocation(e); } else { pressOut = false; } } public void mouseMoved(MouseEvent e){} public void mouseClicked(MouseEvent e){} public void mouseExited(MouseEvent e){} public void mouseEntered(MouseEvent e){} public void updateLocation(MouseEvent e){ rect.setLocation((x + e.getX())-4, (y + e.getY())-4); point.setLocation(x + e.getX(), y + e.getY()); checkPoint(); cubic.setCurve(start, one, two, end); repaint(); } public void paintComponent(Graphics g){ super.paintComponent(g); update(g); } public void update(Graphics g){ Graphics2D g2 = (Graphics2D)g; Dimension dim = getSize(); int w = dim.width; int h = dim.height; if(firstTime){ // Create the offsecren graphics to render to bi = (BufferedImage)createImage(w, h); big = bi.createGraphics(); // Get some initial positions for the control points start.setLocation(w/2-50, h/2); end.setLocation(w/2+50, h/2); one.setLocation((int)(start.x)+25, (int)(start.y)-25); two.setLocation((int)(end.x)-25, (int)(end.y)+25); // Set the initial positions of the squares that are // drawn at the control points startpt.setLocation((int)((start.x)-4), (int)((start.y)-4)); endpt.setLocation((int)((end.x)-4), (int)((end.y)-4)); onept.setLocation((int)((one.x)-4), (int)((one.y)-4)); twopt.setLocation((int)((two.x)-4), (int)((two.y)-4)); // Initialise the CubicCurve2D cubic.setCurve(start, one, two, end); // Set some defaults for Java2D big.setColor(Color.black); big.setStroke(new BasicStroke(5.0f)); big.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); area = new Rectangle(dim); firstTime = false; } // Clears the rectangle that was previously drawn. big.setColor(Color.white); big.clearRect(0, 0, area.width, area.height); // Set the colour for the bezier big.setPaint(Color.black); // Replace the following line by your own function to // draw the bezier specified by start, one, two, end big.draw(cubic); // Draw the control points big.setPaint(Color.red); big.fill(startpt); big.setPaint(Color.magenta); big.fill(endpt); big.setPaint(Color.blue); big.fill(onept); big.setPaint(new Color(0, 200, 0)); big.fill(twopt); // Draws the buffered image to the screen. g2.drawImage(bi, 0, 0, this); } /* Checks if the rectangle is contained within the applet * window. If the rectangle is not contained withing the * applet window, it is redrawn so that it is adjacent to the * edge of the window and just inside the window. */ void checkPoint(){ if (area == null) { return; } if((area.contains(rect)) && (area.contains(point))){ return; } int new_x = rect.x; int new_y = rect.y; double new_px = point.x; double new_py = point.y; if((rect.x+rect.width)>area.getWidth()){ new_x = (int)area.getWidth()-(rect.width-1); } if(point.x > area.getWidth()){ new_px = (int)area.getWidth()-1; } if(rect.x < 0){ new_x = -1; } if(point.x < 0){ new_px = -1; } if((rect.y+rect.width)>area.getHeight()){ new_y = (int)area.getHeight()-(rect.height-1); } if(point.y > area.getHeight()){ new_py = (int)area.getHeight()-1; } if(rect.y < 0){ new_y = -1; } if(point.y < 0){ new_py = -1; } rect.setLocation(new_x, new_y); point.setLocation(new_px, new_py); } }

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  • What have you learnt that has a steep learning curve?

    - by Jonathan Khoo
    Recently, I've invested time in learning the intricacies of Git and it has got me thinking about time and learning. (My previous experience with version control systems was only limited use of CVS and SVN.) It took me a whole day's worth of reading to be able to understand the concepts and differences of Git. There are an infinite number of things available for us to learn. Some, more useful than others. I don't know Fortran - I'm relatively young. But looking back at the preceding years of my life, I notice that I'm busier and busier as time goes on. The amount of things I have to get through in a day is increasingly out of my control. It doesn't take a genius to extrapolate that information and realise I'll have even less time in the future - unless I get fired, but I have no strong plans relating to that idea for now. So, given that I have much more time and energy now than I will have in the future: what have you learnt, that has a steep learning curve, that you would possibly recommend to a fellow programmer? Edit: I've stumbled upon the excellent question What programming skills have provided you the best return on investment? and hav realised that my way of approaching how to spend learning time was naive - it doesn't matter if ten useful concepts can be learnt in the time of one if they're worth it.

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  • Elliptic Curve Diffie-Hellman

    - by cmaduro
    Does the Elliptic curve diffie hellman calculation look any different from the standard one defined here: /* * The basic Diffie-Hellman Key Agreement Equation * * The client initiates * A = g^a mod p * * Sends (g p A) to the server * * The server calculates B * B = g^b mod p * * Sends B back to client * * The client calculates K * K = B^a mod p * * The server calucaltes K * K = A^b mod p * */ Or is it just a specific way of selecting g, a, p and b? How are g,a,p and b selected anyway?

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  • Rotating object along bezier curve: not rotating enough?

    - by Paul
    I tried to follow the instructions from the threads on the forum (Cocos2d rotating sprite while moving with CCBezierBy) with Unity, in order to rotate my object as it moves along a bezier curve. But it does not rotate enough, the angle is too low, it goes up to 6 instead of 90 for example, as you can see on this image (the y eulerAngle is at 6, I would expect it to be around 90 with this curve) : Would you know why it does this? And how to make the rotation toward the next point? Here is the code (in c# with Unity) : (I am comparing x and z to get the angle, and adding the angle to eulerAngles.y so that it rotates around the y axis) void Update () { if ( Input.GetKey("d") ) start = true; if ( start ){ myTime = Time.time; start = false; } float theTime = (Time.time - myTime) *0.5f; if ( theTime < 1 ) { car.position = Spline.Interp( myArray, theTime );//creates the bezier curve counterBezier += Time.deltaTime; //compare 2 positions after 0.1f if ( counterBezier > 0.1f ){ counterBezier = 0; cbDone = false; newpos = car.position; float angle = Mathf.Atan2(newpos.z - oldpos.z, newpos.x - oldpos.x); angle += car.eulerAngles.y; car.eulerAngles = new Vector3(0,angle,0); } else if ( counterBezier > 0 && !cbDone ){ oldpos = car.position; cbDone = true; } Thanks

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  • Curve-fitting in PHP

    - by Francesc
    Hi, I have a MySql table called today_stats. It has got Id, date and clicks. I'm trying to create a script to get the values and try to predict the next 7 days clicks. How I can predict it in PHP?

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  • Qwt plot not working , simple plot curve not appeat

    - by user1629213
    I followed the example of simple plot in qwt examples to plot a curve. The axis and the graph appear in the Qt main window user interface but the curve not. I assigned values to fit the curve but the curve not appear. Any suggestions and help how to solve the problem? Here is my code MainWindow::MainWindow( int argc, char** argv, QWidget *parent ) : QMainWindow( parent ) , qnode( argc,argv ) { ui.setupUi( this ); // Calling this incidentally connects all ui's triggers to on_...() callbacks in this class. QObject::connect( ui.actionAbout_Qt, SIGNAL( triggered( bool )), qApp, SLOT( aboutQt( ))); // qApp is a global variable for the application ReadSettings( ); setWindowIcon( QIcon( ":/images/icon.png" )); ui.tab_manager->setCurrentIndex( 0 ); // ensure the first tab is showing - qt-designer should have this already hardwired, but often loses it (settings?). QObject::connect( &qnode, SIGNAL( rosShutdown( )), this, SLOT( close( ))); /********************* ** Logging **********************/ ui.view_logging->setModel( qnode.loggingModel( )); QObject::connect( &qnode, SIGNAL( loggingUpdated( )), this, SLOT( updateLoggingView( ))); QObject::connect( &qnode, SIGNAL( graphReceived( )), this, SLOT( onGraphReceived( ))); QObject::connect( &qnode, SIGNAL( parameterReceived( )), this, SLOT( onParameterReceived( ))); /********************* ** Auto Start **********************/ if ( ui.checkbox_remember_settings->isChecked( )) { on_button_connect_clicked( true ); } ui.parameters->setAttribute( Qt::WA_NoMousePropagation ); ui.parameters->setAttribute( Qt::WA_OpaquePaintEvent ); ui.plotgraph->setAttribute( Qt::WA_NoMousePropagation ); ui.plotgraph->setAttribute( Qt::WA_OpaquePaintEvent ); p_plot = new QwtPlot(ui.plotgraph); p_plot->setTitle( "Plot LinVel" ); p_plot->setCanvasBackground( Qt::white ); // Axis p_plot->setAxisTitle( QwtPlot::xBottom, "Time(sec)" ); p_plot->setAxisTitle( QwtPlot::yLeft, "Linear Velocity (m/sec)" ); p_plot->setAxisScale( QwtPlot::yLeft, 0.0, 10.0 ); p_plot->setAxisScale( QwtPlot::xBottom, 0.0, 50.0 ); p_plot->insertLegend( new QwtLegend() ); //samplingThread.start(); QwtPlotGrid *grid = new QwtPlotGrid(); grid->attach( p_plot ); curve = new QwtPlotCurve(); curve->setTitle( "Linear velocity" ); // Set curve styles curve->setPen( Qt::blue, 4 ), curve->setRenderHint( QwtPlotItem::RenderAntialiased, true ); QwtSymbol *symbol = new QwtSymbol( QwtSymbol::Ellipse, QBrush( Qt::yellow), QPen( Qt::red, 2 ), QSize( 8, 8 ) ); curve->setSymbol( symbol); // Assign values to the curve //curve->setSamples(ui.plotgraph.get_linv_g());//yaw_g,trav_g,wall_g; curve->attach( p_plot ); p_plot->resize( 600, 400 ); p_plot->show(); void MainWindow::onGraphReceived( ) { { QMutexLocker locker( &qnode.m_mutex ); } } void MainWindow::onParameterReceived( ) { { QMutexLocker locker( &qnode.m_mutex ); std::vector<double> p_ = qnode.get_parameters(); std::cout << p_[0]<<" "<<p_[1]<<" "<<p_[2]<<" "<<p_[3]<<" "<<p_[4] << std::endl; } } Any help?

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  • Where Are You on the Visualization Maturity Curve?

    - by Celine Beck
    The old phrase “A picture is worth a thousand words” is as true now as ever. Providing the right users with access to the right product data, at the right time, can provide significant benefits to a business. This is especially evident with increasing technical and product complexities, elongated supply chains, and growing pressure to bring innovative products to market faster. With this in mind, it is easy to understand why visualization is an integral part of any successful product lifecycle management (PLM) strategy. At a bare minimum, knowledge workers use multiple individual documents of different formats and structure, and leverage visualization solutions to access information; but the real value of visualization can be fully reaped when it is connected to enterprise applications like PLM and tied to the appropriate business context. The picture below illustrates this visualization maturity curve, as we presented during the last Oracle Open World and the transformational effect that visualization can have on PLM processes and performance (check out the post about AutoVue Key Highlights from Oracle Open World 2012 for more information). Organizations are likely to see greater positive impact on business performance when visualization is connected to enterprise systems, allowing access to information coming from multiple sources, such as PLM, supply chain management (SCM) and enterprise resource planning (ERP). This allows organizations to reach higher levels of collaboration and optimize decision-making capacity as users can benefit from in-context access to visual information. For instance, within a PLM system, a design engineer can access a product assembly and review digital annotations added by other users specific to the engineering change request he is reviewing rather than all historical annotations. The last stage on the curve is what we call augmented business visualization (ABV).  ABV is an innovative framework which lets structured data (from Oracle’s Agile PLM for instance) interact with unstructured data (documents, design, 3D models, etc). With this new level of integration, information coming from multiple sources can be presented in a highly visual fashion; color displays can be used in order to identify parts with specific characteristics (for example pending quality issues) and you can take actions directly from within the context of documents and designs, maximizing user productivity. Those who had the chance to attend our PLM session during Oracle Open World already got a sneak peek of our latest augmented business visualization for Oracle’s Agile PLM. The solution generated a lot of wows. Stephen Porter, CEO at Zero Wait State, indicated in a post entitled “The PLM State: the Manhattan Project-Oracle’s Next Big Secret Weapon” that “this kind of synergy between visualization and PLM could qualify as a powerful weapon differentiating Agile PLM from other solutions.” If you are interested in learning more about ABV for Oracle’s Agile PLM and hear about real examples of usage of visualization at all stages of the visualization maturity curve, don’t miss our Visual Decision Making to Optimize New Product Development and Introduction session during the Oracle Value Chain Summit (Feb. 4-6, 2013, San Francisco). We look forward to seeing you there!

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  • Quadratic bezier curve: Y coordinate for a given X ?

    - by stefan.at.wpf
    Hello, I have a quadratic bezier curve and I need the Y coordinate of a point on the bezier curve for a given X coordinate. I know that in pure maths this can be easily done, but I'm wondering is there's a simple / another way for this in C# / WPF? Is it possible to get the single points used by C# / WPF for drawing the bezier curve and then maybe just loop them and compare the X coordinate of each point with the given X coordinate? BTW for the mathematical way it would be good to know which step for the parameter t of the bezier curve has been choosen by C# / WPF? Any chance to find this out? Probably t is just scaled by / steps for t are 1/(distance of P0 and P2) ? Thank you very much for any hint!

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