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  • C++ Pointers, objects, etc

    - by Zeee
    It may be a bit confusing, but... Let's say I have a vector type in a class to store objects, something like vector, and I have methods on my class that will later return Operators from this vector. Now if any of my methods receives an Operator, will I have any trouble to insert it directly into the vector? Or should I use the copy constructor to create a new Operator and put this new one on the vector?

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  • Per-vertex position/normal and per-index texture coordinate

    - by Boreal
    In my game, I have a mesh with a vertex buffer and index buffer up and running. The vertex buffer stores a Vector3 for the position and a Vector2 for the UV coordinate for each vertex. The index buffer is a list of ushorts. It works well, but I want to be able to use 3 discrete texture coordinates per triangle. I assume I have to create another vertex buffer, but how do I even use it? Here is my vertex/index buffer creation code: // vertices is a Vertex[] // indices is a ushort[] // VertexDefs stores the vertex size (sizeof(float) * 5) // vertex data numVertices = vertices.Length; DataStream data = new DataStream(VertexDefs.size * numVertices, true, true); data.WriteRange<Vertex>(vertices); data.Position = 0; // vertex buffer parameters BufferDescription vbDesc = new BufferDescription() { BindFlags = BindFlags.VertexBuffer, CpuAccessFlags = CpuAccessFlags.None, OptionFlags = ResourceOptionFlags.None, SizeInBytes = VertexDefs.size * numVertices, StructureByteStride = VertexDefs.size, Usage = ResourceUsage.Default }; // create vertex buffer vertexBuffer = new Buffer(Graphics.device, data, vbDesc); vertexBufferBinding = new VertexBufferBinding(vertexBuffer, VertexDefs.size, 0); data.Dispose(); // index data numIndices = indices.Length; data = new DataStream(sizeof(ushort) * numIndices, true, true); data.WriteRange<ushort>(indices); data.Position = 0; // index buffer parameters BufferDescription ibDesc = new BufferDescription() { BindFlags = BindFlags.IndexBuffer, CpuAccessFlags = CpuAccessFlags.None, OptionFlags = ResourceOptionFlags.None, SizeInBytes = sizeof(ushort) * numIndices, StructureByteStride = sizeof(ushort), Usage = ResourceUsage.Default }; // create index buffer indexBuffer = new Buffer(Graphics.device, data, ibDesc); data.Dispose(); Engine.Log(MessageType.Success, string.Format("Mesh created with {0} vertices and {1} indices", numVertices, numIndices)); And my drawing code: // ShaderEffect, ShaderTechnique, and ShaderPass all store effect data // e is of type ShaderEffect // get the technique ShaderTechnique t; if(!e.techniques.TryGetValue(techniqueName, out t)) return; // effect variables e.SetMatrix("worldView", worldView); e.SetMatrix("projection", projection); e.SetResource("diffuseMap", texture); e.SetSampler("textureSampler", sampler); // set per-mesh/technique settings Graphics.context.InputAssembler.SetVertexBuffers(0, vertexBufferBinding); Graphics.context.InputAssembler.SetIndexBuffer(indexBuffer, SlimDX.DXGI.Format.R16_UInt, 0); Graphics.context.PixelShader.SetSampler(sampler, 0); // render for each pass foreach(ShaderPass p in t.passes) { Graphics.context.InputAssembler.InputLayout = p.layout; p.pass.Apply(Graphics.context); Graphics.context.DrawIndexed(numIndices, 0, 0); } How can I do this?

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  • How to Identify Which Hardware Component is Failing in Your Computer

    - by Chris Hoffman
    Concluding that your computer has a hardware problem is just the first step. If you’re dealing with a hardware issue and not a software issue, the next step is determining what hardware problem you’re actually dealing with. If you purchased a laptop or pre-built desktop PC and it’s still under warranty, you don’t need to care about this. Have the manufacturer fix the PC for you — figuring it out is their problem. If you’ve built your own PC or you want to fix a computer that’s out of warranty, this is something you’ll need to do on your own. Blue Screen 101: Search for the Error Message This may seem like obvious advice, but searching for information about a blue screen’s error message can help immensely. Most blue screens of death you’ll encounter on modern versions of Windows will likely be caused by hardware failures. The blue screen of death often displays information about the driver that crashed or the type of error it encountered. For example, let’s say you encounter a blue screen that identified “NV4_disp.dll” as the driver that caused the blue screen. A quick Google search will reveal that this is the driver for NVIDIA graphics cards, so you now have somewhere to start. It’s possible that your graphics card is failing if you encounter such an error message. Check Hard Drive SMART Status Hard drives have a built in S.M.A.R.T. (Self-Monitoring, Analysis, and Reporting Technology) feature. The idea is that the hard drive monitors itself and will notice if it starts to fail, providing you with some advance notice before the drive fails completely. This isn’t perfect, so your hard drive may fail even if SMART says everything is okay. If you see any sort of “SMART error” message, your hard drive is failing. You can use SMART analysis tools to view the SMART health status information your hard drives are reporting. Test Your RAM RAM failure can result in a variety of problems. If the computer writes data to RAM and the RAM returns different data because it’s malfunctioning, you may see application crashes, blue screens, and file system corruption. To test your memory and see if it’s working properly, use Windows’ built-in Memory Diagnostic tool. The Memory Diagnostic tool will write data to every sector of your RAM and read it back afterwards, ensuring that all your RAM is working properly. Check Heat Levels How hot is is inside your computer? Overheating can rsult in blue screens, crashes, and abrupt shut downs. Your computer may be overheating because you’re in a very hot location, it’s ventilated poorly, a fan has stopped inside your computer, or it’s full of dust. Your computer monitors its own internal temperatures and you can access this information. It’s generally available in your computer’s BIOS, but you can also view it with system information utilities such as SpeedFan or Speccy. Check your computer’s recommended temperature level and ensure it’s within the appropriate range. If your computer is overheating, you may see problems only when you’re doing something demanding, such as playing a game that stresses your CPU and graphics card. Be sure to keep an eye on how hot your computer gets when it performs these demanding tasks, not only when it’s idle. Stress Test Your CPU You can use a utility like Prime95 to stress test your CPU. Such a utility will fore your computer’s CPU to perform calculations without allowing it to rest, working it hard and generating heat. If your CPU is becoming too hot, you’ll start to see errors or system crashes. Overclockers use Prime95 to stress test their overclock settings — if Prime95 experiences errors, they throttle back on their overclocks to ensure the CPU runs cooler and more stable. It’s a good way to check if your CPU is stable under load. Stress Test Your Graphics Card Your graphics card can also be stress tested. For example, if your graphics driver crashes while playing games, the games themselves crash, or you see odd graphical corruption, you can run a graphics benchmark utility like 3DMark. The benchmark will stress your graphics card and, if it’s overheating or failing under load, you’ll see graphical problems, crashes, or blue screens while running the benchmark. If the benchmark seems to work fine but you have issues playing a certain game, it may just be a problem with that game. Swap it Out Not every hardware problem is easy to diagnose. If you have a bad motherboard or power supply, their problems may only manifest through occasional odd issues with other components. It’s hard to tell if these components are causing problems unless you replace them completely. Ultimately, the best way to determine whether a component is faulty is to swap it out. For example, if you think your graphics card may be causing your computer to blue screen, pull the graphics card out of your computer and swap in a new graphics card. If everything is working well, it’s likely that your previous graphics card was bad. This isn’t easy for people who don’t have boxes of components sitting around, but it’s the ideal way to troubleshoot. Troubleshooting is all about trial and error, and swapping components out allows you to pin down which component is actually causing the problem through a process of elimination. This isn’t a complete guide to everything that could likely go wrong and how to identify it — someone could write a full textbook on identifying failing components and still not cover everything. But the tips above should give you some places to start dealing with the more common problems. Image Credit: Justin Marty on Flickr     

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  • System low graphic error,asking for some command to fix it

    - by mantra
    While running Ubuntu 12.04 amd64 from USB in safe mode it shows an error that says the system system running in low graphics mode. When I click to reconfigure low graphics mode it prompts: ubuntu@ubuntu: It asks for some command. What should I do? I am a complete beginner on the Linux platform. Should I install it without fixing the graphics, or should I solve the graphics problem before installing?

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  • Which driver should I use with a 9600 GT Mobile?

    - by lisalisa
    I checked the Additional Drivers offered for my card and I saw four options: NVIDIA accelerated graphics drivers (version 173) NVIDIA accelerated graphics drivers (post-release updates) (version 173-updates) NVIDIA accelerated graphics drivers (version current) (Recommended) NVIDIA accelerated graphics drivers (post-release updates)(version current-updates) I'm not sure which one to pick. I want a driver that's stable but also takes advantage of my card's hardware.

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  • Some optimization about the code (computing ranks of a vector)?

    - by user1748356
    The following code is a function (performance-critical) to compute tied ranks of a vector: mergeSort(x,inds,ci); //a sort function to sort vector x of length ci, also returns keys (inds) of x. int tj=0; double xi=x[0]; for (int j = 1; j < ci; ++j) { if (x[j] > xi) { double rankvalue = 0.5 * (j - 1 + tj); for (int k = tj; k < j; ++k) { ranks[inds[k]]=rankvalue; }; tj = j; xi = x[j]; }; }; double rankvalue = 0.5 * (ci - 1 + tj); for (int k = tj; k < ci; ++k) { ranks[inds[k]]=rankvalue; }; The problem is, the supposed performance bottleneck mergeSort(), which is O(NlogN) is several times faster than the other part of codes (which is O(N)), which suggests there is room for huge improvment with the other part of the codes, any advices?

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  • How can I override list methods to do vector addition and subtraction in python?

    - by Bobble
    I originally implemented this as a wrapper class around a list, but I was annoyed by the number of operator() methods I needed to provide, so I had a go at simply subclassing list. This is my test code: class CleverList(list): def __add__(self, other): copy = self[:] for i in range(len(self)): copy[i] += other[i] return copy def __sub__(self, other): copy = self[:] for i in range(len(self)): copy[i] -= other[i] return copy def __iadd__(self, other): for i in range(len(self)): self[i] += other[i] return self def __isub__(self, other): for i in range(len(self)): self[i] -= other[i] return self a = CleverList([0, 1]) b = CleverList([3, 4]) print('CleverList does vector arith: a, b, a+b, a-b = ', a, b, a+b, a-b) c = a[:] print('clone test: e = a[:]: a, e = ', a, c) c += a print('OOPS: augmented addition: c += a: a, c = ', a, c) c -= b print('OOPS: augmented subtraction: c -= b: b, c, a = ', b, c, a) Normal addition and subtraction work in the expected manner, but there are problems with the augmented addition and subtraction. Here is the output: >>> CleverList does vector arith: a, b, a+b, a-b = [0, 1] [3, 4] [3, 5] [-3, -3] clone test: e = a[:]: a, e = [0, 1] [0, 1] OOPS: augmented addition: c += a: a, c = [0, 1] [0, 1, 0, 1] Traceback (most recent call last): File "/home/bob/Documents/Python/listTest.py", line 35, in <module> c -= b TypeError: unsupported operand type(s) for -=: 'list' and 'CleverList' >>> Is there a neat and simple way to get augmented operators working in this example?

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  • Arcball Problems with UDK

    - by opdude
    I'm trying to re-create an arcball example from a Nehe, where an object can be rotated in a more realistic way while floating in the air (in my game the object is attached to the player at a distance like for example the Physics Gun) however I'm having trouble getting this to work with UDK. I have created an LGArcBall which follows the example from Nehe and I've compared outputs from this with the example code. I think where my problem lies is what I do to the Quaternion that is returned from the LGArcBall. Currently I am taking the returned Quaternion converting it to a rotation matrix. Getting the product of the last rotation (set when the object is first clicked) and then returning that into a Rotator and setting that to the objects rotation. If you could point me in the right direction that would be great, my code can be found below. class LGArcBall extends Object; var Quat StartRotation; var Vector StartVector; var float AdjustWidth, AdjustHeight, Epsilon; function SetBounds(float NewWidth, float NewHeight) { AdjustWidth = 1.0f / ((NewWidth - 1.0f) * 0.5f); AdjustHeight = 1.0f / ((NewHeight - 1.0f) * 0.5f); } function StartDrag(Vector2D startPoint, Quat rotation) { StartVector = MapToSphere(startPoint); } function Quat Update(Vector2D currentPoint) { local Vector currentVector, perp; local Quat newRot; //Map the new point to the sphere currentVector = MapToSphere(currentPoint); //Compute the vector perpendicular to the start and current perp = startVector cross currentVector; //Make sure our length is larger than Epsilon if (VSize(perp) > Epsilon) { //Return the perpendicular vector as the transform newRot.X = perp.X; newRot.Y = perp.Y; newRot.Z = perp.Z; //In the quaternion values, w is cosine (theta / 2), where //theta is the rotation angle newRot.W = startVector dot currentVector; } else { //The two vectors coincide, so return an identity transform newRot.X = 0.0f; newRot.Y = 0.0f; newRot.Z = 0.0f; newRot.W = 0.0f; } return newRot; } function Vector MapToSphere(Vector2D point) { local float x, y, length, norm; local Vector result; //Transform the mouse coords to [-1..1] //and inverse the Y coord x = (point.X * AdjustWidth) - 1.0f; y = 1.0f - (point.Y * AdjustHeight); length = (x * x) + (y * y); //If the point is mapped outside of the sphere //( length > radius squared) if (length > 1.0f) { norm = 1.0f / Sqrt(length); //Return the "normalized" vector, a point on the sphere result.X = x * norm; result.Y = y * norm; result.Z = 0.0f; } else //It's inside of the sphere { //Return a vector to the point mapped inside the sphere //sqrt(radius squared - length) result.X = x; result.Y = y; result.Z = Sqrt(1.0f - length); } return result; } DefaultProperties { Epsilon = 0.000001f } I'm then attempting to rotate that object when the mouse is dragged, with the following update code in my PlayerController. //Get Mouse Position MousePosition.X = LGMouseInterfacePlayerInput(PlayerInput).MousePosition.X; MousePosition.Y = LGMouseInterfacePlayerInput(PlayerInput).MousePosition.Y; newQuat = ArcBall.Update(MousePosition); rotMatrix = MakeRotationMatrix(QuatToRotator(newQuat)); rotMatrix = rotMatrix * LastRot; LGMoveableActor(movingPawn.CurrentUseableObject).SetPhysics(EPhysics.PHYS_Rotating); LGMoveableActor(movingPawn.CurrentUseableObject).SetRotation(MatrixGetRotator(rotMatrix));

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  • Why a graphics overflow problem as a result of a for loop?

    - by sonny5
    using System; using System.Drawing; using System.Collections; using System.ComponentModel; using System.Windows.Forms; using System.Data; using System.Drawing.Imaging; using System.Drawing.Drawing2D; public class Form1 : System.Windows.Forms.Form { public static float WXmin; public static float WYmin; public static float WXmax; public static float WYmax; public static int VXmin; public static int VYmin; public static int VXmax; public static int VYmax; public static float Wx; public static float Wy; public static float Vx; public static float Vy; public Form1() { InitializeComponent(); } private void InitializeComponent() { this.ClientSize = new System.Drawing.Size(400, 300); this.Text="Pass Args"; this.Paint += new System.Windows.Forms.PaintEventHandler(this.doLine); //this.Paint += new System.PaintEventHandler(this.eachCornerPix); //eachCornerPix(out Wx, out Wy, out Vx, out Vy); } static void Main() { Application.Run(new Form1()); } private void doLine(object sender, System.Windows.Forms.PaintEventArgs e) { Graphics g = e.Graphics; g.FillRectangle(Brushes.White, this.ClientRectangle); Pen p = new Pen(Color.Black); g.DrawLine(p, 0, 0, 100, 100); // draw DOWN in y, which is positive since no matrix called eachCornerPix(sender, e, out Wx, out Wy, out Vx, out Vy); p.Dispose(); } private void eachCornerPix (object sender, System.EventArgs e, out float Wx, out float Wy, out float Vx, out float Vy) { Wx = 0.0f; Wy = 0.0f; Vx = 0.0f; Vy = 0.0f; Graphics g = this.CreateGraphics(); Pen penBlu = new Pen(Color.Blue, 2); SolidBrush redBrush = new SolidBrush(Color.Red); int width = 2; // 1 pixel wide in x int height = 2; float [] Wxc = {0.100f, 5.900f, 5.900f, 0.100f}; float [] Wyc = {0.100f, 0.100f, 3.900f, 3.900f}; Console.WriteLine("Wxc[0] = {0}", Wxc[0]); Console.WriteLine("Wyc[3] = {0}", Wyc[3]); /* for (int i = 0; i<3; i++) { Wx = Wxc[i]; Wy = Wyc[i]; Vx = ((Wx - WXmin)*((VXmax-VXmin)+VXmin)/(WXmax-WXmin)); Vy = ((Wy - WYmin)*(VYmax-VYmin)/(WYmax-WYmin)+VYmin); Console.WriteLine("eachCornerPix Vx= {0}", Vx); Console.WriteLine("eachCornerPix Vy= {0}", Vy); g.FillRectangle(redBrush, Vx, Vy, width, height); } */ // What is there about this for loop that will not run? // When the comments above and after the for loop are removed, it gets an overflow? g.Dispose(); } }

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  • Multi-threading does not work correctly using std::thread (C++ 11)

    - by user1364743
    I coded a small c++ program to try to understand how multi-threading works using std::thread. Here's the step of my program execution : Initialization of a 5x5 matrix of integers with a unique value '42' contained in the class 'Toto' (initialized in the main). I print the initialized 5x5 matrix. Declaration of std::vector of 5 threads. I attach all threads respectively with their task (threadTask method). Each thread will manipulate a std::vector<int> instance. I join all threads. I print the new state of my 5x5 matrix. Here's the output : 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 It should be : 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 0 0 0 0 0 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3 4 4 4 4 4 Here's the code sample : #include <iostream> #include <vector> #include <thread> class Toto { public: /* ** Initialize a 5x5 matrix with the 42 value. */ void initData(void) { for (int y = 0; y < 5; y++) { std::vector<int> vec; for (int x = 0; x < 5; x++) { vec.push_back(42); } this->m_data.push_back(vec); } } /* ** Display the whole matrix. */ void printData(void) const { for (int y = 0; y < 5; y++) { for (int x = 0; x < 5; x++) { printf("%d ", this->m_data[y][x]); } printf("\n"); } printf("\n"); } /* ** Function attached to the thread (thread task). ** Replace the original '42' value by another one. */ void threadTask(std::vector<int> &list, int value) { for (int x = 0; x < 5; x++) { list[x] = value; } } /* ** Return the m_data instance propertie. */ std::vector<std::vector<int> > &getData(void) { return (this->m_data); } private: std::vector<std::vector<int> > m_data; }; int main(void) { Toto toto; toto.initData(); toto.printData(); //Display the original 5x5 matrix (first display). std::vector<std::thread> threadList(5); //Initialization of vector of 5 threads. for (int i = 0; i < 5; i++) { //Threads initializationss std::vector<int> vec = toto.getData()[i]; //Get each sub-vectors. threadList.at(i) = std::thread(&Toto::threadTask, toto, vec, i); //Each thread will be attached to a specific vector. } for (int j = 0; j < 5; j++) { threadList.at(j).join(); } toto.printData(); //Second display. getchar(); return (0); } However, in the method threadTask, if I print the variable list[x], the output is correct. I think I can't print the correct data in the main because the printData() call is in the main thread and the display in the threadTask function is correct because the method is executed in its own thread (not the main one). It's strange, it means that all threads created in a parent processes can't modified the data in this parent processes ? I think I forget something in my code. I'm really lost. Does anyone can help me, please ? Thank a lot in advance for your help.

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  • Extreme Optimization – Numerical Algorithm Support

    - by JoshReuben
    Function Delegates Many calculations involve the repeated evaluation of one or more user-supplied functions eg Numerical integration. The EO MathLib provides delegate types for common function signatures and the FunctionFactory class can generate new delegates from existing ones. RealFunction delegate - takes one Double parameter – can encapsulate most of the static methods of the System.Math class, as well as the classes in the Extreme.Mathematics.SpecialFunctions namespace: var sin = new RealFunction(Math.Sin); var result = sin(1); BivariateRealFunction delegate - takes two Double parameters: var atan2 = new BivariateRealFunction (Math.Atan2); var result = atan2(1, 2); TrivariateRealFunction delegate – represents a function takes three Double arguments ParameterizedRealFunction delegate - represents a function taking one Integer and one Double argument that returns a real number. The Pow method implements such a function, but the arguments need order re-arrangement: static double Power(int exponent, double x) { return ElementaryFunctions.Pow(x, exponent); } ... var power = new ParameterizedRealFunction(Power); var result = power(6, 3.2); A ComplexFunction delegate - represents a function that takes an Extreme.Mathematics.DoubleComplex argument and also returns a complex number. MultivariateRealFunction delegate - represents a function that takes an Extreme.Mathematics.LinearAlgebra.Vector argument and returns a real number. MultivariateVectorFunction delegate - represents a function that takes a Vector argument and returns a Vector. FastMultivariateVectorFunction delegate - represents a function that takes an input Vector argument and an output Matrix argument – avoiding object construction  The FunctionFactory class RealFromBivariateRealFunction and RealFromParameterizedRealFunction helper methods - transform BivariateRealFunction or a ParameterizedRealFunction into a RealFunction delegate by fixing one of the arguments, and treating this as a new function of a single argument. var tenthPower = FunctionFactory.RealFromParameterizedRealFunction(power, 10); var result = tenthPower(x); Note: There is no direct way to do this programmatically in C# - in F# you have partial value functions where you supply a subset of the arguments (as a travelling closure) that the function expects. When you omit arguments, F# generates a new function that holds onto/remembers the arguments you passed in and "waits" for the other parameters to be supplied. let sumVals x y = x + y     let sumX = sumVals 10     // Note: no 2nd param supplied.     // sumX is a new function generated from partially applied sumVals.     // ie "sumX is a partial application of sumVals." let sum = sumX 20     // Invokes sumX, passing in expected int (parameter y from original)  val sumVals : int -> int -> int val sumX : (int -> int) val sum : int = 30 RealFunctionsToVectorFunction and RealFunctionsToFastVectorFunction helper methods - combines an array of delegates returning a real number or a vector into vector or matrix functions. The resulting vector function returns a vector whose components are the function values of the delegates in the array. var funcVector = FunctionFactory.RealFunctionsToVectorFunction(     new MultivariateRealFunction(myFunc1),     new MultivariateRealFunction(myFunc2));  The IterativeAlgorithm<T> abstract base class Iterative algorithms are common in numerical computing - a method is executed repeatedly until a certain condition is reached, approximating the result of a calculation with increasing accuracy until a certain threshold is reached. If the desired accuracy is achieved, the algorithm is said to converge. This base class is derived by many classes in the Extreme.Mathematics.EquationSolvers and Extreme.Mathematics.Optimization namespaces, as well as the ManagedIterativeAlgorithm class which contains a driver method that manages the iteration process.  The ConvergenceTest abstract base class This class is used to specify algorithm Termination , convergence and results - calculates an estimate for the error, and signals termination of the algorithm when the error is below a specified tolerance. Termination Criteria - specify the success condition as the difference between some quantity and its actual value is within a certain tolerance – 2 ways: absolute error - difference between the result and the actual value. relative error is the difference between the result and the actual value relative to the size of the result. Tolerance property - specify trade-off between accuracy and execution time. The lower the tolerance, the longer it will take for the algorithm to obtain a result within that tolerance. Most algorithms in the EO NumLib have a default value of MachineConstants.SqrtEpsilon - gives slightly less than 8 digits of accuracy. ConvergenceCriterion property - specify under what condition the algorithm is assumed to converge. Using the ConvergenceCriterion enum: WithinAbsoluteTolerance / WithinRelativeTolerance / WithinAnyTolerance / NumberOfIterations Active property - selectively ignore certain convergence tests Error property - returns the estimated error after a run MaxIterations / MaxEvaluations properties - Other Termination Criteria - If the algorithm cannot achieve the desired accuracy, the algorithm still has to end – according to an absolute boundary. Status property - indicates how the algorithm terminated - the AlgorithmStatus enum values:NoResult / Busy / Converged (ended normally - The desired accuracy has been achieved) / IterationLimitExceeded / EvaluationLimitExceeded / RoundOffError / BadFunction / Divergent / ConvergedToFalseSolution. After the iteration terminates, the Status should be inspected to verify that the algorithm terminated normally. Alternatively, you can set the ThrowExceptionOnFailure to true. Result property - returns the result of the algorithm. This property contains the best available estimate, even if the desired accuracy was not obtained. IterationsNeeded / EvaluationsNeeded properties - returns the number of iterations required to obtain the result, number of function evaluations.  Concrete Types of Convergence Test classes SimpleConvergenceTest class - test if a value is close to zero or very small compared to another value. VectorConvergenceTest class - test convergence of vectors. This class has two additional properties. The Norm property specifies which norm is to be used when calculating the size of the vector - the VectorConvergenceNorm enum values: EuclidianNorm / Maximum / SumOfAbsoluteValues. The ErrorMeasure property specifies how the error is to be measured – VectorConvergenceErrorMeasure enum values: Norm / Componentwise ConvergenceTestCollection class - represent a combination of tests. The Quantifier property is a ConvergenceTestQuantifier enum that specifies how the tests in the collection are to be combined: Any / All  The AlgorithmHelper Class inherits from IterativeAlgorithm<T> and exposes two methods for convergence testing. IsValueWithinTolerance<T> method - determines whether a value is close to another value to within an algorithm's requested tolerance. IsIntervalWithinTolerance<T> method - determines whether an interval is within an algorithm's requested tolerance.

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  • Visual C++ doesn't operator<< overload

    - by PierreBdR
    I have a vector class that I want to be able to input/output from a QTextStream object. The forward declaration of my vector class is: namespace util { template <size_t dim, typename T> class Vector; } I define the operator<< as: namespace util { template <size_t dim, typename T> QTextStream& operator<<(QTextStream& out, const util::Vector<dim,T>& vec) { ... } template <size_t dim, typename T> QTextStream& operator>>(QTextStream& in,util::Vector<dim,T>& vec) { .. } } However, if I ty to use these operators, Visual C++ returns this error: error C2678: binary '<<' : no operator found which takes a left-hand operand of type 'QTextStream' (or there is no acceptable conversion) A few things I tried: Originaly, the methods were defined as friends of the template, and it is working fine this way with g++. The methods have been moved outside the namespace util I changed the definition of the templates to fit what I found on various Visual C++ websites. The original friend declaration is: friend QTextStream& operator>>(QTextStream& ss, Vector& in) { ... } The "Visual C++ adapted" version is: friend QTextStream& operator>> <dim,T>(QTextStream& ss, Vector<dim,T>& in); with the function pre-declared before the class and implemented after. I checked the file is correctly included using: #pragma message ("Including vector header") And everything seems fine. Doesn anyone has any idea what might be wrong?

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  • optimize output value using a class and public member

    - by wiso
    Suppose you have a function, and you call it a lot of times, every time the function return a big object. I've optimized the problem using a functor that return void, and store the returning value in a public member: #include <vector> const int N = 100; std::vector<double> fun(const std::vector<double> & v, const int n) { std::vector<double> output = v; output[n] *= output[n]; return output; } class F { public: F() : output(N) {}; std::vector<double> output; void operator()(const std::vector<double> & v, const int n) { output = v; output[n] *= n; } }; int main() { std::vector<double> start(N,10.); std::vector<double> end(N); double a; // first solution for (unsigned long int i = 0; i != 10000000; ++i) a = fun(start, 2)[3]; // second solution F f; for (unsigned long int i = 0; i != 10000000; ++i) { f(start, 2); a = f.output[3]; } } Yes, I can use inline or optimize in an other way this problem, but here I want to stress on this problem: with the functor I declare and construct the output variable output only one time, using the function I do that every time it is called. The second solution is two time faster than the first with g++ -O1 or g++ -O2. What do you think about it, is it an ugly optimization?

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  • Why isn't our c# graphics code working any more?

    - by Jared
    Here's the situation: We have some generic graphics code that we use for one of our projects. After doing some clean-up of the code, it seems like something isn't working anymore (The graphics output looks completely wrong). I ran a diff against the last version of the code that gave the correct output, and it looks like we changed one of our functions as follows: static public Rectangle FitRectangleOld(Rectangle rect, Size targetSize) { if (rect.Width <= 0 || rect.Height <= 0) { rect.Width = targetSize.Width; rect.Height = targetSize.Height; } else if (targetSize.Width * rect.Height > rect.Width * targetSize.Height) { rect.Width = rect.Width * targetSize.Height / rect.Height; rect.Height = targetSize.Height; } else { rect.Height = rect.Height * targetSize.Width / rect.Width; rect.Width = targetSize.Width; } return rect; } to static public Rectangle FitRectangle(Rectangle rect, Size targetSize) { if (rect.Width <= 0 || rect.Height <= 0) { rect.Width = targetSize.Width; rect.Height = targetSize.Height; } else if (targetSize.Width * rect.Height > rect.Width * targetSize.Height) { rect.Width *= targetSize.Height / rect.Height; rect.Height = targetSize.Height; } else { rect.Height *= targetSize.Width / rect.Width; rect.Width = targetSize.Width; } return rect; } All of our unit tests are all passing, and nothing in the code has changed except for some syntactic shortcuts. But like I said, the output is wrong. We'll probably just revert back to the old code, but I'm curious if anyone has any idea what's going on here. Thanks.

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  • How to speed-up a simple method (preferably without changing interfaces or data structures)?

    - by baol
    I have some data structures: all_unordered_m is a big vector containing all the strings I need (all different) ordered_m is a small vector containing the indexes of a subset of the strings (all different) in the former vector position_m maps the indexes of objects from the first vector to their position in the second one. The string_after(index, reverse) method returns the string referenced by ordered_m after all_unordered_m[index]. ordered_m is considered circular, and is explored in natural or reverse order depending on the second parameter. The code is something like the following: struct ordered_subset { // [...] std::vector<std::string>& all_unordered_m; // size = n >> 1 std::vector<size_t> ordered_m; // size << n std::tr1::unordered_map<size_t, size_t> position_m; const std::string& string_after(size_t index, bool reverse) const { size_t pos = position_m.find(index)->second; if(reverse) pos = (pos == 0 ? orderd_m.size() - 1 : pos - 1); else pos = (pos == ordered.size() - 1 ? 0 : pos + 1); return all_unordered_m[ordered_m[pos]]; } }; Given that: I do need all of the data-structures for other purposes; I cannot change them because I need to access the strings: by their id in the all_unordered_m; by their index inside the various ordered_m; I need to know the position of a string (identified by it's position in the first vector) inside ordered_m vector; I cannot change the string_after interface without changing most of the program. How can I speed up the string_after method that is called billions of times and is eating up about 10% of the execution time?

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  • How to speed-up a simple method? (possibily without changing interfaces or data structures)

    - by baol
    Hello. I have some data structures: all_unordered_mordered_m is a big vector containing all the strings I need (all different) ordered_m is a small vector containing the indexes of a subset of the strings (all different) in the former vector position_m maps the indexes of objects from the first vector to their position in the second one. The string_after(index, reverse) method returns the string referenced by ordered_m after all_unordered_m[index]. ordered_m is considered circular, and is explored in natural or reverse order depending on the second parameter. The code is something like the following: struct ordered_subset { // [...] std::vector<std::string>& all_unordered_m; // size = n >> 1 std::vector<size_t> ordered_m; // size << n std::map<size_t, size_t> position_m; // positions of strings in ordered_m const std::string& string_after(size_t index, bool reverse) const { size_t pos = position_m.find(index)->second; if(reverse) pos = (pos == 0 ? orderd_m.size() - 1 : pos - 1); else pos = (pos == ordered.size() - 1 ? 0 : pos + 1); return all_unordered_m[ordered_m[pos]]; } }; Given that: I do need all of the data-structures for other purposes; I cannot change them because I need to access the strings: by their id in the all_unordered_m; by their index inside the various ordered_m; I need to know the position of a string (identified by it's position in the first vector) inside ordered_m vector; I cannot change the string_after interface without changing most of the program. How can I speed up the string_after method that is called billions of times and is eating up about 10% of the execution time?

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  • How can I keep a graphics object centered (like a circle) when zooming in or out on it?

    - by sonny5
    using System; using System.Drawing; using System.Collections; using System.ComponentModel; using System.Windows.Forms; using System.Data; using System.Drawing.Drawing2D; using System.Drawing.Imaging; namespace testgrfx { public class Form1 : System.Windows.Forms.Form { float m_Scalef; float m_Scalefout; Rectangle m_r1; private System.Windows.Forms.Button button2; private System.Windows.Forms.Button button3; private System.ComponentModel.Container components = null; private void InitializeComponent() { m_Scalef = 1.0f; // for zooming purposes Console.WriteLine("opening m_Scalef= {0}",m_Scalef); m_Scalefout = 1.0f; Console.WriteLine("opening m_Scalefout= {0}",m_Scalefout); m_r1 = new Rectangle(50,50,100,100); this.AutoScrollMinSize = new Size(600,700); this.components = new System.ComponentModel.Container(); this.button2 = new System.Windows.Forms.Button(); this.button2.BackColor = System.Drawing.Color.LightGray; this.button2.Location = new System.Drawing.Point(120, 30); this.button2.Name = "button2"; this.button2.Size = new System.Drawing.Size(72, 24); this.button2.TabIndex = 1; this.button2.Text = "Zoom In"; this.button2.Click += new System.EventHandler(this.mnuZoomin_Click); this.Controls.Add(button2); this.button3 = new System.Windows.Forms.Button(); this.button3.BackColor = System.Drawing.Color.LightGray; this.button3.Location = new System.Drawing.Point(200, 30); this.button3.Name = "button3"; this.button3.Size = new System.Drawing.Size(72, 24); this.button3.TabIndex = 2; this.button3.Text = "Zoom Out"; this.button3.Click += new System.EventHandler(this.mnuZoomout_Click); this.Controls.Add(button3); //InitMyForm(); } public Form1() { InitializeComponent(); Text = " DrawLine"; BackColor = SystemColors.Window; // Gotta load these kind at start-up ... not with button assignments this.Paint+=new PaintEventHandler(this.Form1_Paint); } static void Main() { Application.Run(new Form1()); } /// Clean up any resources being used. protected override void Dispose( bool disposing ) { if( disposing ) { if (components != null) { components.Dispose(); } } base.Dispose( disposing ); } // autoscroll2.cs does work private void Form1_Paint(object sender, System.Windows.Forms.PaintEventArgs e) { Graphics dc = e.Graphics; dc.PageUnit = GraphicsUnit.Pixel; dc.PageScale = m_Scalef; Console.WriteLine("opening dc.PageScale= {0}",dc.PageScale); dc.TranslateTransform(this.AutoScrollPosition.X/m_Scalef, this.AutoScrollPosition.Y/m_Scalef); Pen pn = new Pen(Color.Blue,2); dc.DrawEllipse(pn,m_r1); Console.WriteLine("form_paint_dc.PageUnit= {0}",dc.PageUnit); Console.WriteLine("form_paint_dc.PageScale= {0}",dc.PageScale); //Console.Out.NewLine = "\r\n\r\n"; // makes all double spaces } private void mnuZoomin_Click(object sender, System.EventArgs e) { m_Scalef = m_Scalef * 2.0f; Console.WriteLine("in mnuZoomin_Click m_Scalef= {0}",m_Scalef); Invalidate(); // to trigger Paint of entire client area } // try: System.Drawing.Rectangle resolution = Screen.GetWorkingArea(someForm); private void Form1_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e) { // Uses the mouse wheel to scroll Graphics dc = CreateGraphics(); dc.TranslateTransform(this.AutoScrollPosition.X/m_Scalef, this.AutoScrollPosition.Y/m_Scalef); Console.WriteLine("opening Form1_MouseDown dc.PageScale= {0}", dc.PageScale); Console.WriteLine("Y wheel= {0}", this.AutoScrollPosition.Y/m_Scalef); dc.PageUnit = GraphicsUnit.Pixel; dc.PageScale = m_Scalef; Console.WriteLine("frm1_moudwn_dc.PageScale= {0}",dc.PageScale); Point [] mousep = new Point[1]; Console.WriteLine("mousep= {0}", mousep); // make sure to adjust mouse pos.for scroll position Size scrollOffset = new Size(this.AutoScrollPosition); mousep[0] = new Point(e.X-scrollOffset.Width, e.Y-scrollOffset.Height); dc.TransformPoints(CoordinateSpace.Page, CoordinateSpace.Device,mousep); Pen pen = new Pen(Color.Green,1); dc.DrawRectangle(pen,m_r1); Console.WriteLine("m_r1= {0}", m_r1); Console.WriteLine("mousep[0].X= {0}", mousep[0].X); Console.WriteLine("mousep[0].Y= {0}", mousep[0].Y); if (m_r1.Contains(new Rectangle(mousep[0].X, mousep[0].Y,1,1))) MessageBox.Show("click inside rectangle"); } private void Form1_Load(object sender, System.EventArgs e) { } private void mnuZoomout_Click(object sender, System.EventArgs e) { Console.WriteLine("first line--mnuZoomout_Click m_Scalef={0}",m_Scalef); if(m_Scalef > 9 ) { m_Scalef = m_Scalef / 2.0f; Console.WriteLine("in >9 mnuZoomout_Click m_Scalef= {0}",m_Scalef); Console.WriteLine("in >9 mnuZoomout_Click__m_Scalefout= {0}",m_Scalefout); } else { Console.WriteLine("<= 9_Zoom-out B-4 redefining={0}",m_Scalef); m_Scalef = m_Scalef * 0.5f; // make it same as previous Zoom In Console.WriteLine("<= 9_Zoom-out after m_Scalef= {0}",m_Scalef); } Invalidate(); } } // public class Form1 }

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  • how to bind the same vector multiple times using R?

    - by hendrik
    question: how can i bind the same vector, lets say o=c(1,2,3,4) mutiple times to get a matrix like o=array(c(1,2,3,4,1,2,3,4,1,2,3,4), dim(c(4,3)) o [,1] [,2] [,3] [1,] 1 1 1 [2,] 2 2 2 [3,] 3 3 3 [4,] 4 4 4 in a nicer way then: o=cbind(o,o,o) and maybe more generalized (dublicate()?? I need this to specifiy colors for elements in textplot() thx a lot

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