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• 12.04 tablet cursor jumps around when clicking

  - by Larry

  After updating to 12.04 i had to re-install wizardpen-driver (https://help.ubuntu.com/community/TabletSetupWizardpen) to use my Trust tablet. But now when I change the Coordinate Transformation Matrix to anything else but the identity matrix, moving the pen moves the cursor normally, but when I click (or press with the pen) the cursor jumps to the edge of the screen, seemingly depending on how I edit the matrix. I know the tablet isn't broken since this behaviour doesn't occur if I leave the matrix as an identity matrix, and the tablet works perfectly on Windows. -L

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• MATLAB: What is an appropriate Data Structure for a Matrix with Random Variable Entries?

  - by user12707

  I'm working in an area that is related to simulation and trying to design a data structure that can include random variables within matrices. I am currently coding in MATLAB. To motivate this let me say I have the following matrix: [a b; c d] I want to find a data structure that will allow for a, b, c, d to be either real numbers or random variables. As an example, let's say that a = 1, b = -1, c = 2 but let d be a normally distributed random variable with mean 20 and SD 40. The data structure that I have in mind will give no value to d. However, I also want to be able to design a function that can take in the structure, simulate an uniform(0,1), obtain a value for d using an inverse CDF and then spit out an actual matrix. I have several ideas to do this (all related to the MATLAB icdf function) but would like to know how more experienced programmers would do it. In this application, it's important that the structure is as "lean" as possible since I will be working with very very large matrices and memory will be an issue.

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• Java Thread execution on same data

  - by AR89

  first of all here is the code, you can just copy an paste import java.util.ArrayList; public class RepetionCounter implements Runnable{ private int x; private int y; private int[][] matrix; private int xCounter; private int yCounter; private ArrayList<Thread> threadArray; private int rowIndex; private boolean[] countCompleted; public RepetionCounter(int x, int y, int [][]matrix) { this.x = x; this.y = y; this.matrix = matrix; this.threadArray = new ArrayList<Thread>(matrix.length); this.rowIndex = 0; for(int i = 0; i < matrix.length; i++){ threadArray.add(new Thread(this)); } countCompleted = new boolean[matrix.length]; } public void start(){ for (int i = 0; i < threadArray.size(); i++){ threadArray.get(i).start(); this.rowIndex++; } } public void count(int rowIndex) { for(int i = 0; i < matrix[rowIndex].length; i++){ if (matrix[rowIndex][i] == x){ this.xCounter++; } else if (matrix[rowIndex][i] == y){ this.yCounter++; } } } @Override public void run() { count(this.rowIndex); countCompleted[this.rowIndex] = true; } public int getxCounter() { return xCounter; } public void setxCounter(int xCounter) { this.xCounter = xCounter; } public int getyCounter() { return yCounter; } public void setyCounter(int yCounter) { this.yCounter = yCounter; } public boolean[] getCountCompleted() { return countCompleted; } public void setCountCompleted(boolean[] countCompleted) { this.countCompleted = countCompleted; } public static void main(String args[]){ int[][] matrix = {{0,2,1}, {2,3,4}, {3,2,0}}; RepetionCounter rc = new RepetionCounter(0, 2, matrix); rc.start(); boolean ready = false; while(!ready){ for(int i = 0; i < matrix.length; i++){ if (rc.getCountCompleted()[i]){ ready = true; } else { ready = false; } } } if (rc.getxCounter() > rc.getyCounter()){ System.out.println("Thre are more x than y"); } else {System.out.println("There are:"+rc.getxCounter()+" x and:"+rc.getyCounter()+" y"); } } } What I want this code to do: I give to the object a matrix and tow numbers, and I want to know how much times these two numbers occurs in the matrix. I create as many thread as the number of rows of the matrix (that' why there is that ArrayList), so in this object I have k threads (supposing k is the number of rows), each of them count the occurrences of the two numbers. The problem is: if I run it for the first time everything work, but if I try to execute it another time I get and IndexOutOfBoundException, or a bad count of the occurrences, the odd thing is that if I get the error, and modify the code, after that it will works again just for once. Can you explain to me why is this happening?

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• exporting bind and keyframe bone poses from blender to use in OpenGL

  - by SaldaVonSchwartz

  I'm having a hard time trying to understand how exactly Blender's concept of bone transforms maps to the usual math of skinning (which I'm implementing in an OpenGL-based engine of sorts). Or I'm missing out something in the math.. It's gonna be long, but here's as much background as I can think of. First, a few notes and assumptions: I'm using column-major order and multiply from right to left. So for instance, vertex v transformed by matrix A and then further transformed by matrix B would be: v' = BAv. This also means whenever I export a matrix from blender through python, I export it (in text format) in 4 lines, each representing a column. This is so I can then I can read them back into my engine like this: if (fscanf(fileHandle, "%f %f %f %f", &skeleton.joints[currentJointIndex].inverseBindTransform.m[0], &skeleton.joints[currentJointIndex].inverseBindTransform.m[1], &skeleton.joints[currentJointIndex].inverseBindTransform.m[2], &skeleton.joints[currentJointIndex].inverseBindTransform.m[3])) { if (fscanf(fileHandle, "%f %f %f %f", &skeleton.joints[currentJointIndex].inverseBindTransform.m[4], &skeleton.joints[currentJointIndex].inverseBindTransform.m[5], &skeleton.joints[currentJointIndex].inverseBindTransform.m[6], &skeleton.joints[currentJointIndex].inverseBindTransform.m[7])) { if (fscanf(fileHandle, "%f %f %f %f", &skeleton.joints[currentJointIndex].inverseBindTransform.m[8], &skeleton.joints[currentJointIndex].inverseBindTransform.m[9], &skeleton.joints[currentJointIndex].inverseBindTransform.m[10], &skeleton.joints[currentJointIndex].inverseBindTransform.m[11])) { if (fscanf(fileHandle, "%f %f %f %f", &skeleton.joints[currentJointIndex].inverseBindTransform.m[12], &skeleton.joints[currentJointIndex].inverseBindTransform.m[13], &skeleton.joints[currentJointIndex].inverseBindTransform.m[14], &skeleton.joints[currentJointIndex].inverseBindTransform.m[15])) { I'm simplifying the code I show because otherwise it would make things unnecessarily harder (in the context of my question) to explain / follow. Please refrain from making remarks related to optimizations. This is not final code. Having said that, if I understand correctly, the basic idea of skinning/animation is: I have a a mesh made up of vertices I have the mesh model-world transform W I have my joints, which are really just transforms from each joint's space to its parent's space. I'll call these transforms Bj meaning matrix which takes from joint j's bind pose to joint j-1's bind pose. For each of these, I actually import their inverse to the engine, Bj^-1. I have keyframes each containing a set of current poses Cj for each joint J. These are initially imported to my engine in TQS format but after (S)LERPING them I compose them into Cj matrices which are equivalent to the Bjs (not the Bj^-1 ones) only that for the current spacial configurations of each joint at that frame. Given the above, the "skeletal animation algorithm is" On each frame: check how much time has elpased and compute the resulting current time in the animation, from 0 meaning frame 0 to 1, meaning the end of the animation. (Oh and I'm looping forever so the time is mod(total duration)) for each joint: 1 -calculate its world inverse bind pose, that is Bj_w^-1 = Bj^-1 Bj-1^-1 ... B0^-1 2 -use the current animation time to LERP the componets of the TQS and come up with an interpolated current pose matrix Cj which should transform from the joints current configuration space to world space. Similar to what I did to get the world version of the inverse bind poses, I come up with the joint's world current pose, Cj_w = C0 C1 ... Cj 3 -now that I have world versions of Bj and Cj, I store this joint's world- skinning matrix K_wj = Cj_w Bj_w^-1. The above is roughly implemented like so: - (void)update:(NSTimeInterval)elapsedTime { static double time = 0; time = fmod((time + elapsedTime),1.); uint16_t LERPKeyframeNumber = 60 * time; uint16_t lkeyframeNumber = 0; uint16_t lkeyframeIndex = 0; uint16_t rkeyframeNumber = 0; uint16_t rkeyframeIndex = 0; for (int i = 0; i < aClip.keyframesCount; i++) { uint16_t keyframeNumber = aClip.keyframes[i].number; if (keyframeNumber <= LERPKeyframeNumber) { lkeyframeIndex = i; lkeyframeNumber = keyframeNumber; } else { rkeyframeIndex = i; rkeyframeNumber = keyframeNumber; break; } } double lTime = lkeyframeNumber / 60.; double rTime = rkeyframeNumber / 60.; double blendFactor = (time - lTime) / (rTime - lTime); GLKMatrix4 bindPosePalette[aSkeleton.jointsCount]; GLKMatrix4 currentPosePalette[aSkeleton.jointsCount]; for (int i = 0; i < aSkeleton.jointsCount; i++) { F3DETQSType& lPose = aClip.keyframes[lkeyframeIndex].skeletonPose.jointPoses[i]; F3DETQSType& rPose = aClip.keyframes[rkeyframeIndex].skeletonPose.jointPoses[i]; GLKVector3 LERPTranslation = GLKVector3Lerp(lPose.t, rPose.t, blendFactor); GLKQuaternion SLERPRotation = GLKQuaternionSlerp(lPose.q, rPose.q, blendFactor); GLKVector3 LERPScaling = GLKVector3Lerp(lPose.s, rPose.s, blendFactor); GLKMatrix4 currentTransform = GLKMatrix4MakeWithQuaternion(SLERPRotation); currentTransform = GLKMatrix4Multiply(currentTransform, GLKMatrix4MakeTranslation(LERPTranslation.x, LERPTranslation.y, LERPTranslation.z)); currentTransform = GLKMatrix4Multiply(currentTransform, GLKMatrix4MakeScale(LERPScaling.x, LERPScaling.y, LERPScaling.z)); if (aSkeleton.joints[i].parentIndex == -1) { bindPosePalette[i] = aSkeleton.joints[i].inverseBindTransform; currentPosePalette[i] = currentTransform; } else { bindPosePalette[i] = GLKMatrix4Multiply(aSkeleton.joints[i].inverseBindTransform, bindPosePalette[aSkeleton.joints[i].parentIndex]); currentPosePalette[i] = GLKMatrix4Multiply(currentPosePalette[aSkeleton.joints[i].parentIndex], currentTransform); } aSkeleton.skinningPalette[i] = GLKMatrix4Multiply(currentPosePalette[i], bindPosePalette[i]); } } At this point, I should have my skinning palette. So on each frame in my vertex shader, I do: uniform mat4 modelMatrix; uniform mat4 projectionMatrix; uniform mat3 normalMatrix; uniform mat4 skinningPalette[6]; attribute vec4 position; attribute vec3 normal; attribute vec2 tCoordinates; attribute vec4 jointsWeights; attribute vec4 jointsIndices; varying highp vec2 tCoordinatesVarying; varying highp float lIntensity; void main() { vec3 eyeNormal = normalize(normalMatrix * normal); vec3 lightPosition = vec3(0., 0., 2.); lIntensity = max(0.0, dot(eyeNormal, normalize(lightPosition))); tCoordinatesVarying = tCoordinates; vec4 skinnedVertexPosition = vec4(0.); for (int i = 0; i < 4; i++) { skinnedVertexPosition += jointsWeights[i] * skinningPalette[int(jointsIndices[i])] * position; } gl_Position = projectionMatrix * modelMatrix * skinnedVertexPosition; } The result: The mesh parts that are supposed to animate do animate and follow the expected motion, however, the rotations are messed up in terms of orientations. That is, the mesh is not translated somewhere else or scaled in any way, but the orientations of rotations seem to be off. So a few observations: In the above shader notice I actually did not multiply the vertices by the mesh modelMatrix (the one which would take them to model or world or global space, whichever you prefer, since there is no parent to the mesh itself other than "the world") until after skinning. This is contrary to what I implied in the theory: if my skinning matrix takes vertices from model to joint and back to model space, I'd think the vertices should already be premultiplied by the mesh transform. But if I do so, I just get a black screen. As far as exporting the joints from Blender, my python script exports for each armature bone in bind pose, it's matrix in this way: def DFSJointTraversal(file, skeleton, jointList): for joint in jointList: poseJoint = skeleton.pose.bones[joint.name] jointTransform = poseJoint.matrix.inverted() file.write('Joint ' + joint.name + ' Transform {\n') for col in jointTransform.col: file.write('{:9f} {:9f} {:9f} {:9f}\n'.format(col[0], col[1], col[2], col[3])) DFSJointTraversal(file, skeleton, joint.children) file.write('}\n') And for current / keyframe poses (assuming I'm in the right keyframe): def exportAnimations(filepath): # Only one skeleton per scene objList = [object for object in bpy.context.scene.objects if object.type == 'ARMATURE'] if len(objList) == 0: return elif len(objList) > 1: return #raise exception? dialog box? skeleton = objList[0] jointNames = [bone.name for bone in skeleton.data.bones] for action in bpy.data.actions: # One animation clip per action in Blender, named as the action animationClipFilePath = filepath[0 : filepath.rindex('/') + 1] + action.name + ".aClip" file = open(animationClipFilePath, 'w') file.write('target skeleton: ' + skeleton.name + '\n') file.write('joints count: {:d}'.format(len(jointNames)) + '\n') skeleton.animation_data.action = action keyframeNum = max([len(fcurve.keyframe_points) for fcurve in action.fcurves]) keyframes = [] for fcurve in action.fcurves: for keyframe in fcurve.keyframe_points: keyframes.append(keyframe.co[0]) keyframes = set(keyframes) keyframes = [kf for kf in keyframes] keyframes.sort() file.write('keyframes count: {:d}'.format(len(keyframes)) + '\n') for kfIndex in keyframes: bpy.context.scene.frame_set(kfIndex) file.write('keyframe: {:d}\n'.format(int(kfIndex))) for i in range(0, len(skeleton.data.bones)): file.write('joint: {:d}\n'.format(i)) joint = skeleton.pose.bones[i] jointCurrentPoseTransform = joint.matrix translationV = jointCurrentPoseTransform.to_translation() rotationQ = jointCurrentPoseTransform.to_3x3().to_quaternion() scaleV = jointCurrentPoseTransform.to_scale() file.write('T {:9f} {:9f} {:9f}\n'.format(translationV[0], translationV[1], translationV[2])) file.write('Q {:9f} {:9f} {:9f} {:9f}\n'.format(rotationQ[1], rotationQ[2], rotationQ[3], rotationQ[0])) file.write('S {:9f} {:9f} {:9f}\n'.format(scaleV[0], scaleV[1], scaleV[2])) file.write('\n') file.close() Which I believe follow the theory explained at the beginning of my question. But then I checked out Blender's directX .x exporter for reference.. and what threw me off was that in the .x script they are exporting bind poses like so (transcribed using the same variable names I used so you can compare): if joint.parent: jointTransform = poseJoint.parent.matrix.inverted() else: jointTransform = Matrix() jointTransform *= poseJoint.matrix and exporting current keyframe poses like this: if joint.parent: jointCurrentPoseTransform = joint.parent.matrix.inverted() else: jointCurrentPoseTransform = Matrix() jointCurrentPoseTransform *= joint.matrix why are they using the parent's transform instead of the joint in question's? isn't the join transform assumed to exist in the context of a parent transform since after all it transforms from this joint's space to its parent's? Why are they concatenating in the same order for both bind poses and keyframe poses? If these two are then supposed to be concatenated with each other to cancel out the change of basis? Anyway, any ideas are appreciated.

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• Model won't render in my XNA game

  - by Daniel Lopez

  I am trying to create a simple 3D game but things aren't working out as they should. For instance, the mode will not display. I created a class that does the rendering so I think that is where the problem lies. P.S I am using models from the MSDN website so I know the models are compatible with XNA. Code: class ModelRenderer { private float aspectratio; private Model model; private Vector3 camerapos; private Vector3 modelpos; private Matrix rotationy; float radiansy = 0; public ModelRenderer(Model m, float AspectRatio, Vector3 initial_pos, Vector3 initialcamerapos) { model = m; if (model.Meshes.Count == 0) { throw new Exception("Invalid model because it contains zero meshes!"); } modelpos = initial_pos; camerapos = initialcamerapos; aspectratio = AspectRatio; return; } public Vector3 CameraPosition { set { camerapos = value; } get { return camerapos; } } public Vector3 ModelPosition { set { modelpos = value; } get { return modelpos; } } public void RotateY(float radians) { radiansy += radians; rotationy = Matrix.CreateRotationY(radiansy); } public float AspectRatio { set { aspectratio = value; } get { return aspectratio; } } public void Draw() { Matrix world = Matrix.CreateTranslation(modelpos) * rotationy; Matrix view = Matrix.CreateLookAt(this.CameraPosition, this.ModelPosition, Vector3.Up); Matrix projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.ToRadians(45.0f), this.AspectRatio, 1.0f, 10000f); model.Draw(world, view, projection); } } If you need more code just make a comment.

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• Handling Types for Real and Complex Matrices in a BLAS Wrapper

  - by mga

  I come from a C background and I'm now learning OOP with C++. As an exercise (so please don't just say "this already exists"), I want to implement a wrapper for BLAS that will let the user write matrix algebra in an intuitive way (e.g. similar to MATLAB) e.g.: A = B*C*D.Inverse() + E.Transpose(); My problem is how to go about dealing with real (R) and complex (C) matrices, because of C++'s "curse" of letting you do the same thing in N different ways. I do have a clear idea of what it should look like to the user: s/he should be able to define the two separately, but operations would return a type depending on the types of the operands (R*R = R, C*C = C, R*C = C*R = C). Additionally R can be cast into C and vice versa (just by setting the imaginary parts to 0). I have considered the following options: As a real number is a special case of a complex number, inherit CMatrix from RMatrix. I quickly dismissed this as the two would have to return different types for the same getter function. Inherit RMatrix and CMatrix from Matrix. However, I can't really think of any common code that would go into Matrix (because of the different return types). Templates. Declare Matrix<T> and declare the getter function as T Get(int i, int j), and operator functions as Matrix *(Matrix RHS). Then specialize Matrix<double> and Matrix<complex>, and overload the functions. Then I couldn't really see what I would gain with templates, so why not just define RMatrix and CMatrix separately from each other, and then overload functions as necessary? Although this last option makes sense to me, there's an annoying voice inside my head saying this is not elegant, because the two are clearly related. Perhaps I'm missing an appropriate design pattern? So I guess what I'm looking for is either absolution for doing this, or advice on how to do better.

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• Lerping to a center point while in motion

  - by Fibericon

  I have an enemy that initially flies in a circular motion, while facing away from the center point. This is how I achieve that: position.Y = (float)(Math.Cos(timeAlive * MathHelper.PiOver4) * radius + origin.Y); position.X = (float)(Math.Sin(timeAlive * MathHelper.PiOver4) * radius + origin.X); if (timeAlive < 5) { angle = (float)Math.Atan((0 - position.X) / (0 - position.Y)); if (0 < position.Y) RotationMatrix = Matrix.CreateRotationX(MathHelper.PiOver2) * Matrix.CreateRotationZ(-1 * angle); else RotationMatrix = Matrix.CreateRotationX(MathHelper.PiOver2) * Matrix.CreateRotationZ(MathHelper.Pi - angle); } That part works just fine. After five seconds of this, I want the enemy to turn inward, facing the center point. However, I've been trying to lerp to that point, since I don't want it to simply jump to the new rotation. Here's my code for trying to do that: else { float newAngle = -1 * (float)Math.Atan((0 - position.X) / (0 - position.Y)); angle = MathHelper.Lerp(angle, newAngle, (float)gameTime.ElapsedGameTime.Milliseconds / 1000); if (0 < position.Y) RotationMatrix = Matrix.CreateRotationX(MathHelper.PiOver2) * Matrix.CreateRotationZ(MathHelper.Pi - angle); else RotationMatrix = Matrix.CreateRotationX(MathHelper.PiOver2) * Matrix.CreateRotationZ(-1 * angle); } That doesn't work so fine. It seems like it's going to at first, but then it just sort of skips around. How can I achieve what I want here?

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• How to rotate a group of objects around a common center?

  - by user1662292

  I've made a model in 3D Studio Max 9. It consists of a variety of cubes, clyinders etc. In XNA I've imported the model okay and it shows correctly. However, when I apply rotation, each component in the model rotates around it's own centre. I want the model to rotate as a single unit. I've linked the components in 3D Max and they rotate as I want in Max. protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); model = Content.Load<Model>("Models/Alien1"); } protected override void Update(GameTime gameTime) { camera.Update(1f, new Vector3(), graphics.GraphicsDevice.Viewport.AspectRatio); rotation += 0.1f; base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); Matrix[] transforms = new Matrix[model.Bones.Count]; model.CopyAbsoluteBoneTransformsTo(transforms); Matrix worldMatrix = Matrix.Identity; Matrix rotationYMatrix = Matrix.CreateRotationY(rotation); Matrix translateMatrix = Matrix.CreateTranslation(location); worldMatrix = rotationYMatrix * translateMatrix; foreach (ModelMesh mesh in model.Meshes) { foreach (BasicEffect effect in mesh.Effects) { effect.World = worldMatrix * transforms[mesh.ParentBone.Index]; effect.View = camera.viewMatrix; effect.Projection = camera.projectionMatrix; effect.EnableDefaultLighting(); effect.PreferPerPixelLighting = true; } mesh.Draw(); } base.Draw(gameTime); } More Info: Rotating the object via it's properties works fine so I'm guessing there's something up with the code rather than with the object itself. Translating the object also causes the objects to get moved independently of each other rather than as a single model and each piece becomes spread around the scene. The model is in .X format.

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• Please help me debug this little C program on dynamic two-dimensional array? [migrated]

  - by azhi

  I am a newbie here. I have written a little C program, which is to create a two-dimensional matrix. Here is the code: #include <stdio.h> #include <stdlib.h> int **CreatMatrix(int m,int n){ int **Matrix; int i; Matrix=(int**)malloc(m*sizeof(int*)); for(i=0;i<m;i++){ Matrix[i]=(int*)malloc(n*sizeof(int)); } return Matrix; } int main(){ int m,n; int **A; printf("Please input the size of the Matrix: "); scanf("%d%d",&m,&n); A=CreatMatrix(m,n); printf("Please input the entries of the Matrix, which should be integers!\n"); int i,j; for(i=0;i<m;i++){ for(j=0;j<n;j++){ scanf("%d",&A[i][j]); } } printf("The Matrix that you input is:\n"); for(i=0;i<m;i++){ for(j=0;j<n;j++){ printf("%3d ",A[i][j]); } printf("\n"); } for(i=0;i<m;i++) free(A[i]); free(A); } I have run it, and it works fine. But I am not sure if it is right? Can anyone help me debug it?

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• Using getRotationMatrix and getOrientation in Android 2.1

  - by aaronmar

  I've been having issues with this for far too long. This code should output dx,dy,dz for the accelerometer, and a running total of the dx. It should also output azimuth, pitch, and roll. I've used info from http://bit.ly/codeUsed, but to no avail. This code does not correctly output pitch, azimuth, or roll. It outputs 0.0, -0.0, -0.0 for the last three textviews, respectively. Please restore my sanity by helping me switch (event.sensor.getType()) { case Sensor.TYPE_ACCELEROMETER: accelerometerValues = event.values.clone(); case Sensor.TYPE_MAGNETIC_FIELD: geomagneticMatrix = event.values.clone(); sensorReady = true; break; default: break; } if (geomagneticMatrix != null && accelerometerValues != null && sensorReady) { sensorReady = false; float[] R = new float[16]; float[] I = new float[16]; SensorManager.getRotationMatrix(R, I, accelerometerValues, geomagneticMatrix); float[] actual_orientation = new float[3]; SensorManager.getOrientation(R, actual_orientation); tvXCoordinate.setText(accelerometerValues[0] + ""); tvYCoordinate.setText(accelerometerValues[1] + ""); tvZCoordinate.setText(accelerometerValues[2] + ""); floatXTotal += accelerometerValues[0]; tvXTotal.setText(floatXTotal + ""); tvAzimuth.setText(actual_orientation[0] + ""); tvPitch.setText(actual_orientation[1] + ""); tvRoll.setText(actual_orientation[2] + ""); }

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• transpose 1D array of leading dimension N

  - by Simon

  how can i transpose an 1d array of leading dimension N, without extra space ? any language is fine

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• Calculations in a table of data

  - by Christian W

  I have a table of data with survey results, and I want to do certain calculations on this data. The datastructure is somewhat like this: ____________________________________________________________________________________ | group |individual | key | key | key | | | |subkey|subkey|subkey|subkey|subkey|subkey|subkey|subkey|subkey| | | |q|q|q |q |q |q|q|q |q|q|q |q |q |q|q|q |q|q|q |q |q |q|q|q | |-------|-----------|-|-|--|--|---|-|-|--|-|-|--|--|---|-|-|--|-|-|--|--|---|-|-|--| | 1 | 0001 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 | | 1 | 0002 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 | | 1 | 0003 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 | | 2 | 0004 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 | | 2 | 0005 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 | | 3 | 0006 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 | | 4 | 0007 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 |1|7|5 |1 |3 |1|4|1 | ------------------------------------------------------------------------------------ Excuse my poor ascii skills... So, every individual belongs to a group, and has answered some questions. These questions are always grouped in keys and subkeys. Is there any simple method to calculate averages, deviations and similar based on the groupings. Something like public float getAverage(int key, int individual); float avg = getAverage(5,7); I think what I'm asking is what would be the best way to structure the data in C# to make it as easy as possible to work with? I have started making classes for every entity, but I got confused somewhere and something stopped working. So before I continue along this path, I was wondering if there are any other, better, ways of doing this? (Every individual can also have describing variables, like agegroup and such, but that's not important for the base functionality.) Our current solution does all calculations inline in the queries when requesting the data from the database. This works, but it's slow and the number of queries equals questions * individuals + keys * individuals, which could be alot if individual queries. Any suggestions?

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• Need help looping through text file in Objective-C and looping through multidimensional array of dat

  - by Fulvio

  I have a question regarding an iPhone game I'm developing. At the moment, below is the code I'm using to currently I loop through my multidimensional array and position bricks accordingly on my scene. Instead of having multiple two dimensional arrays within my code as per the following (gameLevel1). Ideally, I'd like to read from a text file within my project and loop through the values in that instead. Please take into account that I'd like to have more than one level within my game (possibly 20) so my text file would have to have some sort of separator line item to determine what level I want to render. I was then thinking of having some sort of method that I call and that method would take the level number I'm interested in rendering. e.g. Method to call level based on separator? -(void)renderLevel:(NSString) levelNumber; e.g. Text file example? #LEVEL_ONE# 0,0,0,0,0,0,0,0,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,1,1,1,1,1,1,1,0 0,0,0,0,0,0,0,0,0 #LEVEL_TWO# 1,0,0,0,0,0,0,0,1 1,1,1,1,1,1,1,1,1 1,1,1,1,1,1,1,1,1 1,1,1,1,1,1,1,1,1 1,1,1,1,1,1,1,1,1 0,1,1,1,1,1,1,1,0 1,1,1,1,1,1,1,1,1 0,1,1,1,1,1,1,1,0 1,1,1,1,1,1,1,1,1 0,1,1,1,1,1,1,1,0 1,1,1,1,1,1,1,1,1 0,1,1,1,1,1,1,1,0 1,1,1,1,1,1,1,1,1 1,1,1,1,1,1,1,1,1 1,1,1,1,1,1,1,1,1 1,1,1,1,1,1,1,1,1 1,0,0,0,0,0,0,0,1 Code that I'm currently using: int gameLevel[17][9] = { { 0,0,0,0,0,0,0,0,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,1,1,1,1,1,1,1,0 }, { 0,0,0,0,0,0,0,0,0 } }; for (int row=0; row < 17; row++) { for (int col=0; col < 9; col++) { thisBrickValue = gameLevel[row][col]; xOffset = 35 * floor(col); yOffset = 22 * floor(row); switch (thisBrickValue) { case 0: brick = [[CCSprite spriteWithFile:@"block0.png"] autorelease]; break; case 1: brick = [[CCSprite spriteWithFile:@"block1.png"] autorelease]; break; } brick.position = ccp(xOffset, yOffset); [self addChild:brick]; } }

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• Coordinates in distorted grid

  - by Carsten

  I have a grid in a 2D system like the one in the before image where all points A,B,C,D,A',B',C',D' are given (meaning I know the respective x- and y-coordinates). I need to calculate the x- and y-coordinates of A(new), B(new), C(new) and D(new) when the grid is distorted (so that A' is moved to A'(new), B' is moved to B'(new), C' is moved to C'(new) and D' is moved to D'(new)). The distortion happens in a way in which the lines of the grid are each divided into sub-lines of equal length (meaning for example that AB is divided into 5 parts of the equal length |AB|/5 and A(new)B(new) is divided into 5 parts of the equal length |A(new)B(new)|/5). The distortion is done with the DistortImage class of the Sandy 3D Flash engine. (My practical task is to distort an image using this class where the handles are not positioned at the corners of the image like in this demo but somewhere within it).

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• How do I remove an array dimension where the elements sum to zero?

  - by James

  I am assigning a 3D array, which contains some information for a number of different loadcases. Each row in the array defines a particular loadcase (of which there are 3) and I would like to remove the loadcase (i.e. the row) if ALL the elements of the row (in 3D) are equal to zero. The code I have at the moment is: Array = zeros(3,5) %# Initialise array Numloadcases = 3; Array(:,:,1) = [10 10 10 10 10; 0 0 0 0 0; 0 0 0 0 0;]; %# Expand to a 3D array Array(:,:,2) = [10 10 10 10 10; 0 0 0 0 0; 0 0 0 0 0;]; Array(:,:,3) = [10 10 10 10 10; 0 0 0 0 0; 0 0 20 0 0;]; Array(:,:,4) = [10 10 10 10 10; 0 0 0 0 0; 0 0 20 0 0;]; %# And to remove the second row: for i = 1:Numloadcases if sum(Array(i,:,:)) == 0 Array(i,:,:) = []; end end At the moment, the for loop I have to remove the rows causes an indexing error, as the size of the array changes in the loop. Can anyone see a work around for this?

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• OpenGL, problems with GL_MODELVIEW GL_PROJECTION...

  - by Marcos Roriz

  Guys, I'm trying to finish up my homework but I'm having some problems here on these models on openGL... any Idea why is my draw not happening? One thing that strange is that if I change to gluPerspective it works.. #include <GL/glut.h> #include <stdlib.h> #include <stdio.h> static int shoulder = 0; static int elbow = 0; void init(void) { glClearColor(1.0, 1.0, 1.0, 0.0); } void display(void) { glClear(GL_COLOR_BUFFER_BIT); glPushMatrix(); /* BASE */ glRotatef((GLfloat) shoulder, 0.0, 0.0, 1.0); glTranslatef(1.0, 0.0, 0.0); glPushMatrix(); //glScalef(2.0, 0.4, 1.0); glBegin(GL_QUADS); glColor3f(0, 0, 0); glVertex2f(0.0, 0.0); glVertex2f(0.0, 10.0); glVertex2f(10.0, 10.0); glVertex2f(10.0, 0.0); glEnd(); glPopMatrix(); glPopMatrix(); glutSwapBuffers(); } void reshape(int w, int h) { glViewport(0, 0, (GLsizei) w, (GLsizei) h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho((GLfloat)-w/2, (GLfloat)w/2, (GLfloat)-h/2, (GLfloat)h/2, -1.0, 1.0); // modo de projecao ortogonal glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glTranslatef(0.0, 0.0, -5.0); } void keyboard(unsigned char key, int x, int y) { switch (key) { case 's': shoulder = (shoulder + 5) % 360; glutPostRedisplay(); break; case 'S': shoulder = (shoulder - 5) % 360; glutPostRedisplay(); break; case 'e': elbow = (elbow + 5) % 360; glutPostRedisplay(); break; case 'E': elbow = (elbow - 5) % 360; glutPostRedisplay(); break; case 27: exit(0); break; default: break; } } int main(int argc, char** argv) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB); glutInitWindowSize(800, 400); glutInitWindowPosition(100, 100); glutCreateWindow(argv[0]); init(); glutDisplayFunc(display); glutReshapeFunc(reshape); glutKeyboardFunc(keyboard); glutMainLoop(); return 0; }

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• Grid overlayed on image using javascript, need help getting grid coordinates.

  - by Alos

  Hi I am fairly new to javascript and could use some help, I am trying to overlay a grid on top of an image and then be able to have the user click on the grid and get the grid coordinate from the box that the user clicked. I have been working with the code from the following stackoverflow question: Creating a grid overlay over image. link text Here is the code that I have so far: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> </script> <script type="text/javascript"> var SetGrid = function(el, sz, nr, nc){ //get number of rows/columns according to the 'grid' size //numcols = el.getSize().x/sz; //numrows = el.getSize().y/sz; numcols = 48; numrows = 32; //create table element for injecting cols/rows var gridTable = new Element('table', { 'id' : 'gridTable', 'styles' : { 'width' : el.getSize().x, 'height' : el.getSize().y, 'top' : el.getCoordinates().top, 'left' : el.getCoordinates().left } }); //inject rows/cols into gridTable for (row = 1; row<=numrows; row++){ thisRow = new Element('tr', { 'id' : row, 'class' : 'gridRow' }); for(col = 1; col<=numcols; col++){ thisCol = new Element('td', { 'id' : col, 'class' : 'gridCol0' }); //each cell gets down/up over event... down starts dragging|up stops|over draws area if down was fired thisCol.addEvents({ 'mousedown' : function(){ dragFlag = true; startRow = this.getParent().get('id'); startCol = this.get('id'); }, 'mouseup' : function(){ dragFlag = false; }, 'mouseover' : function(){ if (dragFlag==true){ this.set('class', 'gridCol'+$$('#lvlSelect .on').get('value')); } }, 'click' : function(){ //this.set('class', 'gridCol'+$$('#lvlSelect .on').get('id').substr(3, 1) ); str = $$('#lvlSelect .on').get('id'); alert(str.substr(2, 3)); } }); thisCol.inject(thisRow, 'bottom'); }; thisRow.inject(gridTable, 'bottom'); }; gridTable.inject(el.getParent()); } //sens level selector func var SetSensitivitySelector = function(el, sz, nr, nc){ $$('#lvlSelect ul li').each(function(el){ el.addEvents({ 'click' : function(){ $$('#lvlSelect ul li').set('class', ''); this.set('class', 'on'); }, 'mouseover' : function(){ el.setStyle('cursor','pointer'); }, 'mouseout' : function(){ el.setStyle('cursor',''); } }); }); } //execute window.addEvent('load', function(){ SetGrid($('imagetomap'), 32); SetSensitivitySelector(); }); var gridSize = { x: 48, y: 32 }; var img = document.getElementById('imagetomap'); img.onclick = function(e) { if (!e) e = window.event; alert(Math.floor(e.offsetX/ gridSize.x) + ', ' + Math.floor(e.offsetY / gridSize.y)); } </script> <style> #imagetomapdiv { float:left; display: block; } #gridTable { border:1px solid red; border-collapse:collapse; position:absolute; z-index:5; } #gridTable td { opacity:0.2; filter:alpha(opacity=20); } #gridTable .gridCol0 { border:1px solid gray; background-color: none; } #gridTable .gridCol1 { border:1px solid gray; background-color: green; } #gridTable .gridCol2 { border:1px solid gray; background-color: blue; } #gridTable .gridCol3 { border:1px solid gray; background-color: yellow; } #gridTable .gridCol4 { border:1px solid gray; background-color: orange; } #gridTable .gridCol5 { border:1px solid gray; background-color: red; } #lvlSelect ul {float: left; display:block; position:relative; margin-left: 20px; padding: 10px; } #lvlSelect ul li { width:40px; text-align:center; display:block; border:1px solid black; position:relative; padding: 10px; list-style:none; opacity:0.2; filter:alpha(opacity=20); } #lvlSelect ul li.on { opacity:1; filter:alpha(opacity=100); } #lvlSelect ul #li0 { background-color: none; } #lvlSelect ul #li1 { background-color: green; } #lvlSelect ul #li2 { background-color: blue; } #lvlSelect ul #li3 { background-color: yellow; } #lvlSelect ul #li4 { background-color: orange; } #lvlSelect ul #li5 { background-color: red; } </style> </div> <div id="lvlSelect"> <ul> <li value="0" id="li0">0</li> <li value="1" id="li1">1</li> <li value="2" id="li2">2</li> <li value="3" id="li3">3</li> <li value="4" id="li4">4</li> <li value="5" id="li5" class="on">5</li> </ul> </div> In this example the grid box changes color when the image is grid box is clicked, but I would like to be able to have the coordinates of the box. Any help would be great. Thank you

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• What is SVD(singular value decomposition)

  - by shiva

  How does it actually reduce noise..can you suggest some nice tutorials?

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• Is there a substitute for blockproc in Matlab?

  - by SetchSen

  I've been using blockproc for processing images blockwise. Unfortunately, blockproc is part of the Image Processing Toolbox, which I don't have on my personal computer. Is there a combination of functions in base Matlab that can substitute for blockproc? My initial guess was to use im2col to transform each block into columns, and then arrayfun to process each column. Then I realized that im2col is also a part of the Image Processing Toolbox, so that doesn't solve my problem.

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• Is there a name for this type of algorithm?

  - by rehanift

  I have a 2 dimensional array forming a table: [color][number][shape ] ------------------------- [black][10 ][square ] [black][10 ][circle ] [red ][05 ][triangle] [red ][04 ][triangle] [green][11 ][oval ] and what I want to do is group largest common denominators, such that we get: 3 groups group #1: color=black, number=10, shapes = [square, circle] group #2: color=red, shape=triange, numbers = [05,04] group #3: color=green, number=11, shape = oval I wrote code that will handle a 2 "column" scenario, then I needed to adjusted it for 3 and I was figuring I might as well do it for n. I wanted to check first if there is some literature around this but I can't think of what to start looking for!

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• How to interpolate rotations?

  - by uhuu

  I have two vectors describing rotations; a start rotation A and a target rotation B. How would I best go about interpolating A by a factor F to approach B? Using a simple lerp on the vectors fails to work when more than one dimension needs to be interpolated (i.e. produces undesirable rotations). Maybe building quaternions from the rotation vectors and using slerp is the way to go. But how, then, could I extract a vector describing the new rotation from the resulting quaternion? Thanks in advance.

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• How do I mount a sparse disk image permanently?

  - by Mike

  On Mac OS X 10.6.7, when I mount a sparse disk image (either by double-clicking it or using hdid from the command line), the image: Appears on my desktop Needs to be re-mounted every time I log in I'd like to set up the equivalent of an /etc/fstab which will mount the image when the system boots, and make it permanent - so I don't have to worry if my symbolic links will resolve or not. Is this more trouble than it's worth on a Mac? I noticed that there is no /etc/fstab, and /etc/fstab.hd contains a dire warning: IGNORE THIS FILE. This file does nothing, contains no useful data, and might go away in future releases. Do not depend on this file or its contents. I tried sudo hdid -notremovable <image>, which seemed like half of what I wanted (according to man hdid), but it failed with an error: hdid: attach failed - no mountable file systems.

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• Is it possible to shuffle a 2D matrix while preserving row AND column frequencies?

  - by j_random_hacker

  Suppose I have a 2D array like the following: GACTG AGATA TCCGA Each array element is taken from a small finite set (in my case, DNA nucleotides -- {A, C, G, T}). I would like to randomly shuffle this array somehow while preserving both row and column nucleotide frequencies. Is this possible? Can it be done efficiently? [EDIT]: By this I mean I want to produce a new matrix where each row has the same number of As, Cs, Gs and Ts as the corresponding row of the original matrix, and where each column has the same number of As, Cs, Gs and Ts as the corresponding column of the original matrix. Permuting the rows or columns of the original matrix will not achieve this in general. (E.g. for the example above, the top row has 2 Gs, and 1 each of A, C and T; if this row was swapped with row 2, the top row in the resulting matrix would have 3 As, 1 G and 1 T.) It's simple enough to preserve just column frequencies by shuffling a column at a time, and likewise for rows. But doing this will in general alter the frequencies of the other kind. My thoughts so far: If it's possible to pick 2 rows and 2 columns so that the 4 elements at the corners of this rectangle have the pattern XY YX for some pair of distinct elements X and Y, then replacing these 4 elements with YX XY will maintain both row and column frequencies. In the example at the top, this can be done for (at least) rows 1 and 2 and columns 2 and 5 (whose corners give the 2x2 matrix AG;GA), and for rows 1 and 3 and columns 1 and 4 (whose corners give GT;TG). Clearly this could be repeated a number of times to produce some level of randomisation. Generalising a bit, any "subrectangle" induced by a subset of rows and a subset of columns, in which the frequencies of all rows are the same and the frequencies of all columns are the same, can have both its rows and columns permuted to produce a valid complete rectangle. (Of these, only those subrectangles in which at least 1 element is changed are actually interesting.) Big questions: Are all valid complete matrices reachable by a series of such "subrectangle rearrangements"? I suspect the answer is yes. Are all valid subrectangle rearrangements decomposable into a series of 2x2 swaps? I suspect the answer is no, but I hope it's yes, since that would seem to make it easier to come up with an efficient algorithm. Can some or all of the valid rearrangements be computed efficiently? This question addresses a special case in which the set of possible elements is {0, 1}. The solutions people have come up with there are similar to what I have come up with myself, and are probably usable, but not ideal as they require an arbitrary amount of backtracking to work correctly. Also I'm concerned that only 2x2 swaps are considered. Finally, I would ideally like a solution that can be proven to select a matrix uniformly at random from the set of all matrices having identical row frequencies and column frequencies to the original. I know, I'm asking for a lot :)

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• Two dimensional strings in C++

  - by dada

  I want to write something like 2d strings in C++. I tried with : vector< vector<string> > table; int m,n,i,j; string s; cin>>n>>m; for(i=0;i<n;i++) { for(j=0;j<m;j++) { cin>>s; table[i][j] = s; } } cout << "\n\n\n\n"; for(i=0;i<n;i++) { for(j=0;j<m;j++) { cout<<table[i][j]<<" "; } cout<<"\n"; } no compile errors, but when i enter input like: 10 20 .....#.............. .....#.............. .....#.............. .....#.............. ######.............. .......###.......... .......#.#.......... .......###...####### .............#.....# .............####### It gives me segmentation fault. Why ? What's wrong ? And how it should be done so it would work correctly ? Thank you.

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• How can I use from ismember

  - by ahmad hosseini

  Assuming A=[32512199.30 5401000.29 347.33 32512199.69 5401000.45 347.39 32512199.67 5401001.32 353.58 32512199.96 5401001.50 346.99 32512196.71 5401001.69 346.62 ] and B=[32512199.30 5401000.29 347.33 32512199.69 5401000.45 347.39 32512199.67 5401001.32 347.00 32512198.85 5401000.91 347.25 32512196.71 5401001.69 346.87 ] I want using ismember extract the rows that have same X and Y and different Z. X is first column, Y is the second and Z is third. in A and B I want extract from A 32512199.67 5401001.32 353.58 and 32512196.71 5401001.69 346.62 OR from B 32512199.67 5401001.32 347.00 and 32512196.71 5401001.69 346.87 How can I do it?

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