Matrix Definition and 1000 Threads

The Multistate Anti-Terrorism Information Exchange Program, also known by the acronym MATRIX, was a U.S. federally funded data mining system originally developed for the Florida Department of Law Enforcement described as a tool to identify terrorist subjects.
The system was reported to analyze government and commercial databases to find associations between suspects or to discover locations of or completely new "suspects". The database and technologies used in the system were housed by Seisint, a Florida-based company since acquired by Lexis Nexis.
The Matrix program was shut down in June 2005 after federal funding was cut in the wake of public concerns over privacy and state surveillance.

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  1. J

    What is the Most Efficient Method for Finding the Determinant of an nxn Matrix?

    Homework Statement Shown In the picture. I went to the prof for help he said and i quote :" don't use laplas expansion to find the determinate, it will take you for ever." Homework Equations I don't even know how to do this. prof had no notes on this and Boas is a god awful book for learning...
  2. P

    3x3 matrix inverse unit vector

    Homework Statement Hi! I have the 3x3 matrix for L below, which I calculated. But now I need to figure out how the equation below actually means! Is it just the inverse of L (L^-1)? I cannot proceed if I don't know this step. Homework Equations See image The Attempt at a Solution I put in...
  3. evinda

    MHB Calculating Determinant of $(N+1) \times (N+1)$ Matrix

    Hello! (Wave) Suppose that we are given this $(N+1) \times (N+1)$ matrix: $\begin{bmatrix} -(1+h+\frac{h^2}{2}q(x_0)) & 1 & 0 & 0 & \dots & \dots & 0 \\ -1 & 2+h^2q(x_1) & -1 & 0 & \dots& \dots & 0\\ 0 & -1 & 2+h^2q(x_2) & -1 & 0 & \dots & 0\\ & & & & & & \\ & & & & & & \\ & & & & & & \\...
  4. P

    Difference equation and diagonal block matrix

    Homework Statement Compute ##A^j~\text{for} ~~j=1,2,...,n## for the block diagonal matrix##A=\begin{bmatrix} J_2(1)& \\ &J_3(0) \end{bmatrix}##, And show that the difference equation ##x_{j+1}=Ax_{j}## has a solution satisfying ##|x_{j}|\rightarrow\infty~\text{as}~j\rightarrow\infty##...
  5. S

    MHB Matrix Algebra 2.0 Help: Solving Questions with Cosine Laws

    Hey guys, So I'm stuck on another question from the previous one that I posted and would absolutely love it if I can get some help regarding how to attempt this. I literally have no clue at how to go by solving it. I have a feeling for question one that the cosine laws might come in handy but...
  6. L

    Prove that a zero-one matrix can only have 1's after 5th power

    Hello, I couldn't give the full explanation in the title - I am talking about a particular matrix. Given the matrix: A[1] = 0 0 1 1 0 0 1 1 0 A[5] = 1 1 1 1 1 1 1 1 1 Once it gets to the 5th boolean power, it becomes all 1's, and any power greater than or equal to 5 will always produce a...
  7. B3NR4Y

    Comp Sci Store values in an arbitrarily sized matrix C++

    Homework Statement "Calculate the max, min, count, average, and standard deviation (std dev) of a set of numbers. The formula for average is: average is sum divided by count The formula for standard deviation is stddev is the square root of the variance The formula for variance is variance is...
  8. askhetan

    Matrix Elements as images of basis vectors

    I'm trying to understand the maths of QM from Shankar's book - Principles of Quantum Mechanics: On page 21 of that book, there is a general derivation that if we have a relation: |v'> = Ω|v> Where Ω is a operator on |v> transfroming it into |v'>, then the matrix entries of the operator can be...
  9. D

    Find eigenvalues and eigenvectors of weird matrix

    Homework Statement find eigenvalues and eigenvectors for the following matrix |a 1 0| |1 a 1| |0 1 a| Homework EquationsThe Attempt at a Solution I'm trying to find eigenvalues, in doing so I've come to a dead end at 1 + (a^3 - lambda a^2 -2a^2 lambda + 2a lambda^2 + lambda^2 a - lambda^3 - a...
  10. brotherbobby

    Proving "Rotation Matrix is Orthogonal: Necessary & Sufficient

    I'd like to prove the fact that - since a rotation of axes is a length-preserving transformation, the rotation matrix must be orthogonal. By the way, the converse of the statement is true also. Meaning, if a transformation is orthogonal, it must be length preserving, and I have been able to...
  11. kostoglotov

    Matrix is Invertible: is this notation ok?

    Quick question, not even sure if I should post it here, but I can't think where else. If I wanted to write the short hand of A is an invertible matrix, would it be ok to just write A \ \exists A^{-1} ?
  12. ognik

    MHB Help with Matrix & Operator specifics

    Hi, those who have seen my recent posts will know that I am trying to put together a simple table that I am certain will help me get through a cloud of uncertainty that is proving a major obstacle to my on-going studies. I refer to...
  13. W

    What is the angle between coupled forces with a given moment and magnitude?

    Homework Statement The moment of the couple is 600k (N-m). What is the angle A? F = 100N located at (5,0)m and pointed in the positive x and positive y direction -F = 100N located at (0,4)m and pointed in the negative x and negative y direction Homework Equations M = rxF M = DThe Attempt at a...
  14. I

    MATLAB How to Calculate Squares and Cubes in MATLAB?

    We want to know the square and the cube of each of the following numbers: 1, 2 and 3. You can have MATLAB obtain these results as follows. Create a vector [1 2 3] . Create a vector [2 3]. Use these two vectors as inputs to the meshgrid function (with the 3-element vector as the first argument)...
  15. Activeuser

    Ladder operators and matrix elements...

    Please I need your help in such problems.. in terms of ladder operators to simplify the calculation of matrix elements... calculate those i) <u+2|P2|u> ii) <u+1| X3|u> If u is different in both sides, then the value is 0? is it right it is 0 fir both i and ii? when exactly equals 0, please...
  16. ognik

    MHB How Can I Simplify Matrix and Operator Concepts for My Studies?

    Hi, I feel thoroughly muddled like I am drowning in a soup of terminology and notation, and I have assignment deadlines. So I have tried to compile a rough table that will give me a consistent base which I can use now - and add to going forward; trying also to stick with the usage in my...
  17. mester1025

    Ray tracing with transfer matrix method

    Hi, I'm new in physics and optics so I need a little help. I've a simple optical system from 2 thin lenses. The first thin lens has a focal distance of 50 [mm] , and the second one has 25 [mm]. The 2 lenses are separated by 40 [mm] and the object is placed 75 [mm] before the first lens. I've to...
  18. fluidistic

    Length contraction via Lorentz transformation matrix

    1,2,3. Homework Statement I tried to derive the length contraction using the Lorentz transformation matrix and considering 2 events. I reached the correct result but there's a step that I had to assume that I don't understand. Consider a ruler of length L along the x-axis for an observer at...
  19. Diffie Heltrix

    Norm indueced by a matrix with eigenvalues bigger than 1

    Suppose we pick a matrix M\in M_n(ℝ) s.t. all its eigenvalues are strictly bigger than 1. In the question here the user said it induces some norm (|||⋅|||) which "expands" vector in sense that exists constant c∈ℝ s.t. ∀x∈ℝ^n |||Ax||| ≥ |||x||| . I still cannot understand why it's correct. How...
  20. S

    Calculating Matrix Representation of Linear Function in New Basis

    Homework Statement Let ##f : \mathbb{R}^n \rightarrow \mathbb{R}^m## be a linear function. Suppose that with the standard bases for ##\mathbb{R}^n## and ##\mathbb{R}^m## the function ##f## is represented by the matrix ##A##. Let ##b_1, b_2, \ldots, b_n## be a new set of basis vectors for...
  21. S

    Full Rank Matrix: Determinant Condition | Rank-Nullity Theorem

    Homework Statement Show that the matrix ##A## is of full rank if and only if ##ad-bc \neq 0## where $$A = \begin{bmatrix} a & b \\ b & c \end{bmatrix}$$ Homework EquationsThe Attempt at a Solution Suppose that the matrix ##A## is of full rank. That is, rank ##2##. Then by the rank-nullity...
  22. S

    Charge conjugation matrix and Dirac equation's solutions

    I saw this somewhere but I think it is wrong... I already read Griffiths' "Introduction to Particle Physics" (the 1st edition) from the page 216 to the page 222 (chapter of Quantum Electrodynamics - section "Solution to the Dirac Equation") and I didn't understood why was there the imaginary...
  23. kostoglotov

    What is this Matrix question asking me to do?

    It's from the chapter on Matrix Inverses... imgur link: http://i.imgur.com/8OhFzgi.jpg This is the entirety of the exercise. It's not following on from or setting anything else up. That's just number 42...what can I do with this?
  24. FOIWATER

    Can the Induced Matrix Norm be Proven with Triangle Inequality?

    Hi, I found a statement without a proof. It seems simple enough, but I am having trouble proving it because I am not positive about induced matrix norms. The statement is that $$||A^k|| \leq||A||^{k}$$ for some matrix A and positive integer k. I have found that the norm of a matrix is the...
  25. T

    How Do You Calculate the Density Matrix in Second Quantization?

    Homework Statement Homework Equations and attempt at solution I think I got the ground state, which can be expressed as |\Psi \rangle = \prod_{k}^{N}\hat{a}_{k}^{\dagger} |0 \rangle . Then for the density matrix I used: \langle...
  26. N

    S matrix Unitarity Proof, pg 298 Peskin Schroeder

    I have a question regarding a derivation in Peskin and Schroeder's QFT book. On page 298, he is discussing a method for defining a gauge invariant S matrix. He does this by defining projection operators ##P_0## that project general particle states into gauge invariant states, and then defining...
  27. B

    Degree of liberty of a matrix 2x2

    How many degree of liberty exist, actually, in a matrix 2x2 ? I think that is three! Because the conic equation can be wrote like this: \begin{bmatrix} A & B\\ C & D \end{bmatrix} :\begin{bmatrix} x^2 & xy\\ yx & y^2 \end{bmatrix} + \begin{bmatrix} E\\ F \end{bmatrix} \cdot \begin{bmatrix}...
  28. gfd43tg

    ODE 45 with coupled ODE's in a matrix, reactor temp.

    Homework Statement My question is regarding part (e), I just gave all the questions for reference. Homework EquationsThe Attempt at a Solution These are the coupled equations I should solve (from part d) My issue is using ode45 to get ##C_{A}(t)##, ##C_{P}(t)##, and ##T(t)##. Here is my...
  29. RJLiberator

    Proving Matrix Transformation Property

    Homework Statement Let A and B be n x m matrices, and λ and μ be real numbers. Prove that: (λA+μB)^T = λA^T+μB^t Homework Equations :/ The Attempt at a Solution I'm struggling to start here. If there was no λ and μ, I think I'd be able to reasonably solve this. How do I show that these...
  30. C

    Can the entries of a Matrix be elements of an unordered set?

    Most definitions of a matrix that I have seen involve entries that are elements of a field. What if I have a unorderd set with no operations defined on it, say a set of different colored marbles or a set of historical events. Can I have a matrix whose entries are elements of such a set?
  31. RJLiberator

    Find All Possible Matrix Inverses

    Homework Statement Find 2x2 matrices A and B, all of whose entries are \begin{align} &\geq 0 \end{align}, such that A^-1 and B^-1 exist, but (A+B)^-1 does not exist. Homework Equations The insverse is defined as 1/determinat(matrix) * adj(matrix) Otherwise shown as...
  32. kostoglotov

    How are the x1 and x4 values determined in the solution to the matrix equation?

    Hi, rapid fire posting in this subforum I know, sorry if that's annoying. Let me know if I should space my posts out a bit more. Here's an image of the solution to a worked example (from Intro to Linear Algebra 4th by Strang) here's the imgur link: http://i.imgur.com/IG6r15H.jpg I cannot...
  33. E

    Determinant of 3x3 matrix equal to scalar triple product?

    The determinant of a 3x3 matrix can be interpreted as the volume of a parallellepiped made up by the column vectors (well, could also be the row vectors but here I am using the columns), which is also the scalar triple product. I want to show that: ##det A \overset{!}{=} a_1 \cdot (a_2 \times...
  34. P

    Matrix Representation of a Uniform Sphere Centered at the Origin

    What is the basic matrix form for a uniform (unit) sphere centered at the origin? Given a vector that specifies the radii (1,1,1) == (r1,r2,r3), I would like the matrix that implies no rotation (is it [[1,0,0],[0,1,0],[0,0,1]]?) and covers the rest of the necessary parameters. I am testing...
  35. D

    Lorentz transformation matrix and its inverse

    Given the Lorentz matrix Λuv its transpose is Λvu but what is its transpose ? I have seen ΛuaΛub = δb a which implies an inverse. This seems to be some sort of swapping rows and columns but to get the inverse you also need to replace v with -v ? Also In the LT matrix is it the 1st slot...
  36. E

    Linear Transformation and isomorphisms

    Homework Statement Suppose a linear transformation T: [P][/2]→[R][/3] is defined by T(1+x)= (1,3,1), T(1-x)= (-1,1,1) and T(1-[x][/2])=(-1,2,0) a) use the given values of T and linearity properties to find T(1), T(x) and T([x][/2]) b) Find the matrix representation of T (relative to standard...
  37. E

    Bases and Coordinates: B1 and B2 for [R][/3] - Homework Statement

    Homework Statement Let B1={([u][/1]),([u][/2]),([u][/3])}={(1,1,1),(0,2,-1),(1,0,2)} and B2={([v][/1]),([v][/2]),([v][/3])}={(1,0,1),(1,-1,2),(0,2,1)} a) Show that B1 is a basis for [R][/3] b) Find the coordinates of w=(2,3,1) relative to B1 c)Given that B2 is a basis for [R[/3], find...
  38. B

    How to form the transformation matrix for this

    We were asked to form the transformation matrix that rotates the x1 axis of a rectangular coordinate system 60 degrees toward x2 and the x3 axis. The thing is, I don't understand what it meant by rotating one axis toward the two other. Like, do I rotate x1 60 degrees toward the x2-x3 plane or...
  39. B

    Evaluate the partial derivative of a matrix element

    Homework Statement A determinant a is defined in the following manner ar * Ak = Σns=1 ars Aks = δkr a , where a=det(aij), ar , Ak , are rows of the coefficient matrix and cofactor matrix respectively. The second term in the equation is the expansion over the columns of both matrices, δkr is...
  40. G

    Dynamic allocation of adjacency matrix and traversing a list

    Homework Statement I have a binary tree. I need to print a path of a doubly circular linked list (0 and 1) after every user input. I have a code in which user inputs data about one person. For example, when user inputs 2 elements, the path should be 0->1. In my code, it won't print any path...
  41. Y

    A system of equations that I want to do with a matrix

    Homework Statement Below are four equations, with the known quantities listed. Solve these equations to obtain an expression for ##T## in terms of known quantities only. Do the same to obtain an expression for ##a## ##T-f=m_1a\hspace{5mm}N-m_1g\cos\theta=0## ##m_2g-T=m_2a \hspace{5mm} f=\mu N##...
  42. SteliosVas

    Expressing Matrix Power as linear combination

    Homework Statement Okay I am given a matrix A = [2 1 ; 3 4] The first step is to find numbers of a and b such that A2 + aA + bI = [0 0; 0 0] I is an identity matrix (2x2). Part B - After that is says to use the result of the above to express A5 as a linear combination of A and I Homework...
  43. duc

    Method to solve a coupled system of matrix equation

    Hello everyone, I'm struggling with a coupled of matrix equations of the general form: AX + CY = cX BY + DX = cY where A, B, C and D are hermitics square matrices. X, Y and c are the eigenvector and eigenvalue to be found. I'm looking for a method or an algorithm to solve this system by using...
  44. R

    Kalman filter a posteriori estimate covariance matrix

    I am having some trouble deriving the a posteriori estimate covariance matrix for the linear Kalman filter. Below I have shown my workings for two methods. Method one is fine and gives the expected result. Method two is the way I tried to derive it initially before further expanding out terms to...
  45. B

    MATLAB Want gray scale image of a matrix in matlab

    I am creating a gray-scale image of a 2000*2000 matrix using mat2gray and imshow command.But highest number of matrix entries that imshow can implement is 500*500 approximately.After that it shows------ "Warning: Image is too big to fit on screen; displaying at 8% > In...
  46. JonnyMaddox

    Hamilton Operator for particle on a circle -- Matrix representation....

    Hey JO. The Hamiltonian is: H= \frac{p_{x}^{2}+p_{y}^{2}}{2m} In quantum Mechanics: \hat{H}=-\frac{\hbar^{2}}{2m}(\frac{\partial^{2}}{\partial x^{2}}+\frac{\partial^{2}}{\partial x^{2}}) In polar coordinates: \hat{H}=-\frac{\hbar^{2}}{2m}( \frac{\partial^{2}}{\partial r^{2}}+\frac{1}{r}...
  47. JesseJC

    Given vectors, constructing a matrix

    Homework Statement Say you've been given vectors v1, v2 and v3. Homework EquationsThe Attempt at a Solution How do I construct a matrix out of these three vectors? Am I to use the given vectors as columns or rows in a matrix? When does this matter and when does it not? This may be a stupid...
  48. T

    Get matrix A from a series of elementary matrices

    1. Get A from its inverse3. I believe it has something to do with the theorem that states: E1E2E3...EkA=I
  49. S

    Linear transformation 2 x 2 matrix problem

    Homework Statement [/B] Find a 2 x 2 matrix that maps e1 to –e2 and e2 to e1+3e2Homework Equations [/B] See the above notesThe Attempt at a Solution [/B] I am making a pig's ear out of this one. I think I can get e1 to –e2 3 -1 1 -3 but as far as getting it to reconcile a matrix like...
  50. O

    IMSL diagonalizing a general complex matrix (DEVCCG)

    Under some circumstances, whenever I call DEVCCG to diagonalize a general complex matrix, the program gets stuck inside and never returns. I do not even get out an error code so that I may continue with the rest of the program. I assume the iterative diagonalization inside the procedure does not...
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