is a mathematical object to be recorded in a [usually] rectangular array of elements of ring or field, which (table) is a set of rows and columns are located at the intersection of its elements. The number of rows and columns specify the size of the matrix.

learn more… | top users | synonyms

0
votes
0answers
18 views

Accelerometer - coordinate system transformation

I'm getting some accelerometer readings from an Android phone, but it comes in on the phone's coordinate system. I want to apply a transformation to put the acceleration in the world coordinate system ...
0
votes
0answers
19 views

How to generate Golay sequence?

I am trying to follow the 25.213 3GPP spec point 5.2.3.1 to generate Golay sequence for the P-SCH channel. I was able to do it recursively for Hadamard sequences, but I am unsure of what golay ...
0
votes
0answers
15 views

Why do we assume the matrix of impulse responses to be a Toeplitz matrix during deconvolution

$y(n)$ = output signal $x(n)$ = input signal $\mathbf H$ = system response as a toeplitz matrix $$\mathbf H = ...
0
votes
2answers
86 views

How is the sound converted to matrix in Matlab?

I am using the audioread(filename,y,Fs) function of Matlab and it converts an audio file to a matrix. I want to know how is each value of that matrix generated. Is ...
0
votes
1answer
29 views

Hessian Matrix. Second partial derivative test

I have a question about the hessian matrix / determinant of the hessian matrix. For the Hessian matrix, one is able to determine the local curvature around a point. And with the Second partial ...
0
votes
1answer
44 views

what is happening when i run this code line? [closed]

I have the following MATLAB code: x=[1 2 3; 4 5 6; 7 8 9;]; u=(0:255)/(255-1).^1.05; x2=u(x+1) when I run this code I get the following as a result in ...
0
votes
0answers
36 views

Multiplying two large sparse matrices

I am having two big large sparse matrices A, B, suppose M=256, ...
0
votes
0answers
181 views

How to calculate the scale, rotation angle and translation between 2 images if we know the homography result matrix?result

I got the result of findHomorgraphy in OpenCv. As below: Homography transform matrix: [-1.1534205416542787 0.7834287271121142 527.9064589440736 -0.2415444621693116 0.16412191792642924 ...
1
vote
2answers
78 views

Maximising each element in a matlab array

Is it possible to construct an array A, without looping, where A(i,j) = max(B(i),C(j)) and B ...
1
vote
0answers
22 views

Emulate signal loss of a pixellated detector in Python?

I have a matrix 64x64 where each cell represents the pixel of a pixellated detector. The spacial response of this detector decreases by going further from its center (that is, coordinates "31,31" or ...
0
votes
0answers
42 views

Compute gradient and divergence within region (subdomain)

I want to compute gradient and divergence within specific region in a image. For the gradient, I use forward difference and for the divergence, I use backward difference. In matlab, I set the mask ...
2
votes
1answer
52 views

What does “kernel based” mean?

In my thesis I try to explain what kernel based methods are, especially the meaning for object detection. I know kernel based methods like Mean- and CamShift and I know how to use them. I understand ...
0
votes
0answers
13 views

Internal constaint of essential matrix

I work on visual odometry program and I use EmguCV. I use calibrated camera to detect features from current frame with SURF, and match them with previous using Knn. Because I have calibrated camera I ...
0
votes
1answer
47 views

Mat and int are incompatible? [closed]

anybody knows what this is? Mat mat = (Mat_<double>(3, 4) << 0, 0, width, width, 0, height, height, 0, 1, 1, 1, 1); I dont know what mat would be in ...
1
vote
0answers
36 views

Sensor Data Fusion with Orientation Sensors in 3D Euclidian Space

Preconditions For measuring the position of a mobile device in 3D space, I utilize two sensors with different characteristics that measure device orientation. Sensor A (a combined sensor of ...
0
votes
0answers
21 views

Find similarity rating in trajectories

I've got trajectories encoded in black and white. These are stored in a matrix with dimensions 150x150 (i.e. black = 1, white = 0). An example of two trajectories below (plotted): My objective is ...
0
votes
0answers
92 views

Generating Wavelet family matrixes

We have unnormalized Haar matrix which, is for example, H4=[1 1 1 1;1 1 -1 -1;1 -1 0 0;0 0 1 -1] After normalizing it, we use for haar transform. I know how to ...
3
votes
1answer
104 views

5.1 Rear To 5.1 Side mixing matrix

I am searching for a matrix definition for converting a audio signal (5.1 with rear) to a audio signal (5.1 with side). Currently I am using the definitions from: ...
1
vote
0answers
29 views

Matrix expansion into bases

I have an image (that is a matrix), let's say of dimensions NxN. I then want to expand this matrix into M basis matrices (for the moment I'm still unsure how many M of these basis matrices I should ...
0
votes
1answer
58 views

Is there a way to perform 2-D image rotation by matrix multiplication?

In my understanding, unlike shifting and scaling, image rotation actually rotates the coordinates whereby interpolating the pixels at discrete positions. It is like a projection that discrete values ...
2
votes
0answers
65 views

Distribution of a signal covariance matrix

A common estimation problem in signal processing assumes the following signal model \begin{equation} \mathbf{r} = \sum_{i=1}^{Q}\alpha_i\mathbf{s}\left(w_i\right)+\mathbf{n} \end{equation} where ...
0
votes
0answers
21 views

Are there condition numbers associated with the STFT, DWT?

Recently I learned that the DFT has good numerical stability since it can be represented as an orthogonal matrix, which has a condition number of 1. Is it possible to represent the STFT and DWT as ...
0
votes
1answer
570 views

How to get relative rotation matrix from two orientation values in android?

Following http://www.codeproject.com/Articles/729759/Android-Sensor-Fusion-Tutorial , I get two orientation values. Then, I transform those values to rotation matrices R1, R2. I think the relative ...
0
votes
1answer
305 views

Convert a 1D array into a 'rotated' 2D matrix

simply put, let's say I have this array - [1 2 1] I want to try and get this output in Matlab [1 1 1 1 2 1 1 1 1] It's like my array was 'rotated' ...
0
votes
1answer
663 views

PSNR of two images of different size in matlab

I performed bicubic interpolation on a 256*256 image(img) dest = interp2(img,'bicubic') and i got a 511 * 511 image.I want to compute PSNR of a 512 * 512 ...
-1
votes
1answer
281 views

Difference between correlation/convolution and matrix multiplication

Can anyone please clarify the difference between correlation/convolution and matrix multiplication? As I thought either convolution or correlation is similar to matrix multiplication. I read this ...
1
vote
0answers
69 views

How to replace Hadamard Product and Column wise addition with new Matrix operation?

Let $$ A= \begin{bmatrix} a_{1,1} & a_{1,2} & a_{1,3}\\ a_{2,1} & a_{2,2} & a_{2,3}\\ a_{3,1} & a_{3,2} & a_{3,3}\\ \end{bmatrix} $$ and $$ B= ...
2
votes
1answer
183 views

What is a covariance matrix?

Suppose you have k samples from each of the N elements of a uniform linear array (ULA) of sensors: What is the physical meaning of a covariance matrix? How do you form a covariance matrix with the ...
1
vote
0answers
46 views

Solving an array signal processing estimation problem based on the Rayleigh quotient

The Rayleigh quotient for a covariance matrix $\mathbf{C}$ and a non-zero steering vector $\mathbf{a}$ is given by $$ R(\mathbf{C},\mathbf{a}) := ...
2
votes
0answers
95 views

Least Angle without matrix inversion?

Sorry if this is too damned long. I did what I could to abbreviate it. I'm new to numerical work with matrices. I believe I have a way to compute Least Angle without explicit matrix inversion. I'm ...
1
vote
3answers
119 views

How to compute regions of matrix

Let's say we have the following matrix: 0 0 0 0 0 0 0 1 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 1 0 0 0 0 0 0 I want to calculate the ...
0
votes
0answers
80 views

Matching 2 undirected weighted graph in matlab

Consider 2 undirected weighted graph as shown in figure.Consider first graph as G1 and second graph as G2.Graph G1 consist of vertices V={F1,F2,F3,F4,F5} and Graph G2 consist of vertices ...
1
vote
0answers
141 views

How to understand energy function in thin plate splines?

guys! I have carried out some experiments using matlab warp tools from here. But the results are not good, so I decide to read its original paper Principal Warps: Thin-Plate Splines and the ...
0
votes
1answer
796 views

reconstruction of time series in SSA

i am trying to reconstruct time series from SSA ,because according to this link http://en.wikipedia.org/wiki/Singular_spectrum_analysis there is procedure ...
0
votes
0answers
39 views

How to calculate the freedom of projection matrix?

I learned projection matrix from textbook. It says that the 9th is redundant, so it has 8 freedom. But I can not know the reason clearly. Following the equations. I can not understand why i does ...
0
votes
1answer
50 views

Expectation of product of hermitian matrix

Let $\textbf{h} \in \mathbb{C}^{N\times 1}$, $\textbf{a} \in \mathbb{C}^{N\times 1}$, $\textbf{b} \in \mathbb{C}^{N\times 1}$ and $\textbf{c} \in \mathbb{C}^{N\times 1}$. The variable $h_i$ is defined ...
0
votes
1answer
48 views

Matrix form of STFT

IS there a Matrix form of the STFT that could be applied to a signal directly, as in the case of DFT? We know the matrix structure of the DFT Matrix. Can we derive that somehow for a STFT Transform? ...
0
votes
0answers
190 views

How to Prevent overflow/saturation in fixed point implementation of Fast Data Projection Algorithm

I am trying to implement an algorithm in real-time on a Fixed point DSP (The Blackfin from Analog Devices). The algorithm does a lot of stuff, but in the middle it performs an algorithm called "Fast ...
0
votes
1answer
132 views

Incoherence: Compressed Sensing (CS) vs Matrix Completion (MC)

I am seeking a clarification of the concept of Incoherence within the MC framework. Specifically, 1) the literature mentions the application of a "strong incoherence" given a set of assumptions. ...
0
votes
1answer
122 views

how to calculate cross correlation of transient signal?

there. Let me have a noisy speech signal $y(k)$ as below. $$ y(k) = x(k) + v(k) $$ where, $k$ is the discrete-time index, $x(k)$ is clean speech signal, $v(k)$ is a zero-mean random process, ...
0
votes
0answers
395 views

3 Band Wavelet Transform In MATLAB

I am currently working on an audio watermarking project in MATLAB. I currently have a code I am using to construct a nxn 3 Band Wavelet Transform matrix. However, when I try to construct a matrix that ...
2
votes
1answer
116 views

A good Digital Image Processing environment

i'm looking for a free/opensource solution for digital image processing with reasonable performances processing quite large images (e.g. actual smartphones have resolutions of 8-10Mpx) and being ready ...
1
vote
2answers
412 views

Covariance matrix explanation

I am trying to understand and visualize the concept of a covariance matrix. Suppose I have a matrix: $A = \begin{pmatrix} 2 & 3 & 4\\ 5 & 5 & 6 \end{pmatrix}$ how do I calculate its ...
2
votes
0answers
81 views

Can Cholesky outer product version result in negative square roots?

Say A is symmetric positive definite matrix , which means one necessary condition is diagonal entries of A are positive. If I do cholesky factorisation using outer product form, Can there be any ...
2
votes
1answer
6k views

understanding FFT2 function of Matlab

I am trying to understand what happen when we take FFT2 of a matrix in a matlab. first have a look at this simple example, ...
2
votes
1answer
115 views

Reflection Rotation matrix

I'm doing a rigid body between point clouds using SVD. Sometimes the routine produces an incorrect rotation matrix with a Determinant=-1, ie a reflection matrix. Any idea why ? Is there a valid way ...
0
votes
2answers
603 views

Matlab BOC (binary offset carrier)

I am trying to implement a binary offset carrier (BOC) direct sequence spread spectrum scheme in MATLAB. In that scheme, a code $c(t)$ (a binary vector which repeats after a certain number of zeros ...
1
vote
1answer
409 views

Apply Low Pass (Smoothing) Filter on a Set of Matrices and Reject Outliers

Given a set of a $ 3 $ by $ 3 $ matrices $ {H}_{i} $. Each matrix is an Homography matrix. They are used to stabilize Video Stream. Yet some of them are outliers which creates "Jumps" in the ...
4
votes
2answers
1k views

Shortest geometric distance from surface in 3d dataset?

I have a three-dimensional binary image of a collection of discrete, individual voxels ("seeds") contained in a connected 3-dimensional surface ("skin"). (Like a small fruit, with a surface delineated ...
7
votes
2answers
852 views

Why do we deal with the eigenvectors of the autocorrelation instead of the data itself?

How intuitively to understand why eigenvectors of the autocorrelation matrix are used, but eigenvectors of the matrix constructed from temporal samples have no sense and aren't used? For example, in ...