matrix

An exception on OpenCV matrix Function

Hello guys! I am quite a newbie on OpenCV, and I am just about finished my first big program with it. Actually, I would be if a nasty exception wasn't happening. Here it is: OpenCV Error: Bad flag (parameter or structure field) (Unrecognized or unsupport ed array type) in unknown function, file ........\ocv\opencv\src\cxcore\cxarr ay.cpp...

what function or loop do I have to use to average the matrix?

Hey I want to find the average of all the matrix: Data=(Data{1}+......+Data{n})/n) where Data{n} is a matrix of m*n.. Thank you sooo much ...

PHP sharpness convolution martix

I'm using a convolution matrix for sharpness in PHP GD and I want to change the sharpness "level". Where would I make changes to this if I want to make it more or less sharp? $image = imagecreatefromjpeg('pic.jpg'); $matrix = array( array(0, -1, 0), array(-1, 5, -1), array(0, -1, 0) ); imageconvolution($image, $matrix, 1, 0...

Java Matrix processing time

Hi All, I need simple opinion from all Guru! I developed a program to do some matrix calculations. It work all fine with small matrix. However when I start calculating BIG thousands column row matrix. It kills the speed. I was thinking to do processing on each row and write the result in a file then free the memory and start process...

image too sharp when zoomed out

I have a zoomable/scrollable image that is of high quality. When i zoom out, the image looks way too sharp. Is there a way to blur the image out a bit so i can code it to blur when it reaches a certain zoom level or is there a better way to go about this? For now i actually have a lower res version of my image that loads when the user hi...

Access to i and j variables in Maxima's matrixmap?

Hi All, I'm still a maxima newbie so bear with me. I am trying to write my own formula for calculating the adjoint of a matrix (I know maxima already has one built-in, but I was trying my own as a learning exercise). So far I have (for a 3x3 matrix): /* cofactor of some submatrix of the matrix, by deleting row i and column j */ cof(i, ...

Cairo Matrix equivillant of GlOrtho Matrix?

Given that I do something like this: void glOrtho( GLdouble left, GLdouble right, GLdouble bottom, GLdouble top, GLdouble nearVal, GLdouble farVal); and the result is: http://www.opengl.org/sdk/docs/man/xhtml/glOrtho.xmlw could I achieve a matrix like this: http://cairographics.org/manual...

Java CSV row separation

Hi All, I am working with CSV in java. I am having one problem or you can say I don't know how to do it :) I have a CSV file that is as follow: a,4,5,3,2 b,6,4,6,7 c,5,3,7,2 2d,1,4,5,9 4e,4,2,5,7 m4,7,5,3,6 . . . xyz,1,6,4,8 I want to get all the rows from CSV which contains these following labels in first column, I have all followi...

android render issue causing delays ?

Hi, I'm developing an Android game and I've got the garbage collection to the point where it GC's only about once every 5 minutes or so, which I think is acceptable, for now. The problem is that, every once in a while, I'll see this message in the logs: 08-29 09:58:46.410 W/copybit ( 1912): stretch_copybit::run_render fail 08-29 09:59...

Finding The Max of sum of elements in matrix in distinct rows and columns

Hi, I have a nxm matrix and I need to find the maximum of sum of its values in distinct rows and columns. For example considering the following Matrix: m1 m2 m3 n1 1 2 3 n2 4 5 6 n3 7 8 9 n4 10 11 12 The max will be 12+8+4 = 24 Note that finding the max and eliminating all values belonging to that column or ...

Matrix3DProjection exists in Silverlight but not in WPF ?

I need a taper-effect on my transform in WPF. Charles Petzold wrote some nice stuff about it for example : http://www.charlespetzold.com/blog/2009/07/Using-the-Matrix3DProjection-Class-in-Silverlight-3.html But now it seems that the used Matrix3DProjection class only exists in Silverlight, and NOT in WPF..? (Why would Mirosoft think it ...

Dependency Matrix for C# code

The dependency matrix of VS 2010 crashes VS 2010 as soon a I try it on my application! Anyone knows a good VS addin with a solid dependency matrix? ...

Simulating Ocean Water, need to compute complicated values.

Simulating Ocean Water: http://www.finelightvisualtechnology.com/docs/coursenotes2004.pdf I'm trying to simulate ocean and I need your help. Please be patient, I'm newbie to computer graphics but I know basics of physics and mathematics. As you can see I need to compute the formula: k is a vector, x is a coordinate (so I suggest that...

How to get transformations from transformation matrix in Flash?

I have transformation matrix properties (a,b,c,d). How to calculate scaleX, scaleY, scewX, scewY and rotation angle from those values? When only one type of transformation is applied, I can figure out that: scaleX = a scaleY = d scewX = c scewY = b rotation = arccos(a) or -arcsin(c) But when multiple transformations are applied at on...

Code libraries/applications in C#

I am refreshing my memory on C# (first used it several years ago), and I want to look at some real world quality code (rather than the simplistic ones used in many books). My preference would be mathematical/statistics libraries written in C# as I would like to see how Matrices and PDEs (partial differential equations etc) are implement...

permuting the rows and columns of a matrix for clustering

i have a distance matrix that is 1000x1000 in dimension and symmetric with 0s along the diagonal. i want to form groupings of distances (clusters) by simultaneously reordering the rows and columns of the matrix. this is like reordering a matrix before you visualize its clusters with a heatmap. i feel like this should be an easy proble...

Multiply rows of matrix by vector?

I'm optimizing a function and I want to get rid of slow for loops. I'm looking for a faster way to multiply each row of a matrix by a vector. Any ideas? EDIT: I'm not looking for a 'classical' multiplication. Eg. I have matrix that has 23 columns and 25 rows and a vector that has length of 23. In a result I want to have matrix 25x23...

What's the fastest way to represent and multiply sparse boolean matrices?

So, I'm using boolean matrices whose dimension is usually a couple dozen to a couple hundred, they are usually quite sparse (just some 2-4 non-zeros in most rows and columns) and my runtime is heavily dominated by their multiplication. What datastructure suits best for speeding up multiplication under these circumstances? Currently I'm...

Numpy matrix operations

I want to compute the following values for all i and j: M_ki = Sum[A_ij - A_ik - A_kj + A_kk, 1 <= j <= n] How can I do it using Numpy (Python) without an explicit loop? Thanks! ...

Projecting a 3D point to 2D screen space using a perspective camera matrix

Hi everyone, I am attempting to project a series of 3D points onto the screen using a perspective camera matrix. I do not have world space (or consider it being an identity matrix) and my camera does not have camera space (or consider it an identity matrix), I do have a 4x4 matrix for my object space. I am taking the object matrix and ...