Matrices Definition and 1000 Threads

  1. F

    Similarity of Diagonalizable Matrices

    Homework Statement A = {{2,1,0}{0,-2,1}{0,0,1}} and B = {{3,2,-5}{1,2,-1}{2,2,-4}} Show that A and B are similar by showing that they are similar to the same diagonal matrix. Then find an invertible matrix P such that P-1AP=B Homework Equations P-1AP=B, or AP=PB The Attempt at a...
  2. H

    MATLAB Using or Creating block matrices in Matlab

    I am trying to put a lot of data into a matrix to call upon later in plotting. From a masterfile, I need to call on the (:,1) values on x and y, and the (:,2) values in x and y. It is easy to construct a 12x3 matrix to contain all of this information, however when I am plotting I want to call...
  3. K

    Mathematica Help me to solve Do-loop for large matrices (Mathematica)

    Hi all, I have difficulties about applying the Do-loop command as it takes very long time to run (more than 24 hours and it keeps running). However, if i do it manually, without Do command, i.e. putting the values of the variables, Mathematica gives me a pretty quick output. Please see...
  4. M

    Hermitian operators without considering them as Matrices

    A Hermitian matrix is a square matrix that is equal to it's conjugate transpose. Now let's say I have a Hermitian operator and a function f: [ H.f ] The stuff in the square is the complex conjugate as the functions are in general complex. If I do not consider the matrix representation of...
  5. B

    Rank of AB: How nxn Matrices A & B Determine Rank

    check that, for any nxn matrices A,B then rank(AB) (> or =) rank A +rank(B)-n
  6. B

    Simultaneously unitarily diagonalizeable matrices commute

    Homework Statement Matrices A and B are simultaneously unitarily diagonalizeable. Prove that they commute. Homework Equations As A and B are simultaneously unitarily diagonalizeable, there exists a unitary matrix P such that P^{-1}AP = D_{1} and P^{-1}BP = D_{2}, where D_{1} and D_{2}...
  7. V

    Groups and orthogonal matrices question

    Let A and B be nxn matrices which generate a group under matrix multiplication. Assume A and B are not orthogonal. How can I determine an nxn matrix X such that X-1AX and X-1BX are both orthogonal matrices? Is it possible to do this without any special knowledge of the group in question?
  8. A

    Simple gamma matrices question

    Hi I've just read the statement that a matrix that commutes with all four gamma matrices / Dirac matrices has to be a multiple of the identity. I don't see that; can anyone tell me why this is true? Thanks in advance
  9. C

    Gamma matrices and projection operator question on different representations

    Typically I understand that projection operators are defined as P_-=\frac{1}{2}(1-\gamma^5) P_+=\frac{1}{2}(1+\gamma^5) where typically also the fifth gamma matrices are defined as \gamma^5=i\gamma^0\gamma^1\gamma^2\gamma^3 and.. as we choose different representations the projection...
  10. C

    Gamma matrices projection operator

    Typically I understand that projection operators are defined as P_-=\frac{1}{2}(1-\gamma^5) P_+=\frac{1}{2}(1+\gamma^5) where typically also the fifth gamma matrices are defined as \gamma^5=i\gamma^0\gamma^1\gamma^2\gamma^3 and.. as we choose different representations the projection...
  11. matqkks

    What is the most convenient way to introduce matrices to students?

    What is the most convenient way to introduce matrices to students?
  12. T

    MATLAB To concatinate multiple like matrices in MATLAB

    I have a problem regarding concatination of multiple matrices in MATLAB. For finite number of matrices there exists a command called cat or we may even put the matrices directly in a matrix representation format to get the desired concatenation. Like, for A and B to form a matrix C in...
  13. E

    The Determinant of a Matrix of Matrices

    Hi, Suppose we have the following matrix: \begin{center}\begin{pmatrix}\mathbf{L}&\mathbf{A}^T\\\mathbf{A}&\mathbf{0}\end{pmatrix}\end{center} where L is n-by-n matrix, A is m-by-n matrix. How to find the determinant of this square matrix? Thanks in advance
  14. L

    How do you find the basis for the spanning set which contains matrices?

    Please look at the link: http://gyazo.com/5f57caddf7dc76aa61d387f2915d29fe.png
  15. H

    Linear Transformations and Matrices

    Let L:P1 >> P1 be a linear transformation for which we know that L(t + 1) = 2t + 3 and L(t - 1) = 3t -2 a) Find L(6t-4) I just want to check the way to calculate this question. Is L(6t - 4) equal to 6*3t - 4*2 = 18t - 8? if not, how to calculate it?
  16. kini.Amith

    Are Matrices with the Same Eigenvalues Always Similar?

    given that 2 matrices have the same eigenvalues is it necessary that they be similar? If not, what is the connection between those 2?
  17. X

    Vectors, Matrices and Determinants. Oh my.

    I never really enjoyed learning the theory of maths and generally tried to avoid it at all costs since leaving University. However I'm looking at learning kinematic and dynamic chassis modelling and it requires extesive use of vectors and their transformations. I can follow the problems in...
  18. K

    Embedding Complex Matrices into Real Spaces

    Hey all, I have a quick question that should hopefully be simple to answer. Consider a the space of n \times n matrices over \mathbb C given by M_n(\mathbb C) . In order to properly consider this as a real matrix, we have to embed M_n(\mathbb C) \to M_{2n}(\mathbb R) , and I can give some...
  19. R

    Properties Of Matrices with the same Column Space

    Homework Statement Suppose that A and B are 5 x 5 matrices with the same Column Space (image). (a) Must they have the same columns? (b) Must they have the same rank? (c) Must they have kernels of the same dimension? (d) Must they have the same kernel? (e) If A is invertible, must B be...
  20. D

    What does a row of zeros indicate in a 4x5 matrix?

    Homework Statement Given a 4x5 matrix, what could a row of 0's represent geometrically? The Attempt at a Solution Given a scalar PLANE equation, you could make a 3x3 matrix and solve the system of equations. A row of zeroes there could represent a consisten but dependent...
  21. M

    Tensor product of matrices with different size

    Homework Statement Hi, I attached a file involving my problem and attempt at a solution.Thanks. Homework Equations The Attempt at a Solution
  22. C

    Is there a way to show that Ak is unitarily similar to Bk using induction?

    Homework Statement SUppose A and B are nxn matrices in the complex field and that A is unitarily similar to B. Homework Equations Show that Ak is unitarily similar to Bk for all k=1,2,3,.. The Attempt at a Solution I used induction to show its true for k=1 which it is. Then for...
  23. C

    Showing two matrices are not unitarily similar

    Let A= |1 2| |0 3| and B= |1 0| |0 3| Show that A and B are not unitarily similar?
  24. T

    Help with MatLab/C++ Loops (Heat Transfer, Matrices)

    Basically, I need to solve a transient heat transfer conduction problem. I've got most of the work done but I need to solve the problem using MATLAB or C++ or some other kind of coding. That's what I need help with. The actual aspects of the problem aren't really that important, so I will try...
  25. S

    Linear algebra square matrices

    Homework Statement A and B are two matrices n X n Homework Equations AB-BA=identity matrix It is critical for me to prove that the are no matrices that are capable to hold the above equation true The Attempt at a SolutionI made several efforts.I had the idea to get the main...
  26. B

    Solution to a linear equation of matrices

    Hi, How can I solve the equation below for M. G*inv(A+G'*inv(M)*G)*G'+F+M=0 G' is the transpose of G and inv(.) is the inverse of a matrix. Thanks
  27. C

    Question about normal matrices

    Homework Statement Suppose A is a normal matrix in the complex field.Homework Equations Show that ||Ax||=||A*x|| for all x in the complex fieldThe Attempt at a Solution If A is normal then AA*=A*A and ||Ax||=(Ax,Ax)=(x,A*Ax)
  28. L

    Converting between Covariant and Contravariant matrices

    Homework Statement Given a matrix {latex] A_11 =A_22 = 0 A_12 =A_21 = x/y +y/x [ /latex] Find the contravariant components in polar coordinates. Answer: [itex] A_11 = 2 A_22 = -2/r^2 A_12 = 2cot(2 /theta)/r [ /latex] Homework Equations I used the polar coordinates metric to raise...
  29. L

    Solving Linear Equations with Matrices: Help Needed

    A set of m linear equations in n unknowns has the m × n matrix A of coefficients and the m × 1 (column) vector hT of right-hand sides. (Later we shall write this as AxT=hT). T = transpose In each of cases (a) to (d) below, answer as many as possible of the following...
  30. E

    The basis of n x n matrices with matrix multiplication

    Hi All, I recently came across the interesting notion of constructing the minimal set of nxn matrices that can be used as a basis to generate all nxn matrices given that matrix multiplication, and addition and multiplication by scalar are allowed. Is there a way to construct an explicit set...
  31. H

    Solving an equation including matrices

    Homework Statement Okay. So I have an equation: ABA + BAB = 2I where A and B are square nxn-matrices and I is the identity matrix. From this, I am supposed to find a way to express B as a function of A (given that A is close to I). So B = F(A), and it is also given that F(I) = I. Homework...
  32. B

    Prove A^-1=(A^T A)^-1 A^T (matrices)

    For a general, non-singular matrix A prove that A^-1=[(A^T A)^-1] A^T The Attempt at a Solution tried searching in textbook and internet-nothing yet someone somewhere must know an easy way to do this without having to sit there for five hours getting stuck but i just look at...
  33. B

    Surjection Between Mapping Class Grp. and Symplectic Matrices

    Hi, Everyone: I am reading a paper that refers to a "natural surjection" between M<sub>g</sub> and the group of symplectic 2gx2g-matrices. All I know is this map is related to some action of M<sub>g</sub> on H<sub>1</sub>(S<sub>g</sub>,Z). I think this action is...
  34. D

    Trace Theorems and Dirac Matrices

    I think I'm missing something real simple on trace theorems and Dirac matrices, but am just not seeing it. In the Peskin and Schroeder QFT text on page 135 we have: gamma^(mu)*gamma^(nu)*gamma_(mu) = -2*gamma^(nu) But, why can't we anti-commute and obtain the following...
  35. H

    Commutators spanning the matrices

    Let T be the set of all matrics of the form AB - BA, where A and B are nxn matrics. Show that span T is not Mnn. 1) does "span T is not Mnn" mean that Mnn does not span T? Thanks
  36. P

    Confused about col/rows of matrices

    Can someone tell me (when RREFing a matrix) when do we put the vectors of a subspace in columns of a matrix and when in rows? Example from my notes: Here, my prof put the vectors in columns: and here, he put the vectors in rows: Thanks!
  37. S

    Understanding Jacobian Matrices - Working Through Examples

    I get the idea of Jacobian matrices. I think. Working through different examples, I don't have any problems. For example, f1 = x^2 + y^2 f2 = 3x + 4y would result in [2x 2y] [3 4] Similarly, by my understanding, something like x^2 + y^2 3y + 4x would result in [2x...
  38. M

    Understanding Matrix Multiplication: Solving Homework Problems (5) and (24)

    Homework Statement Homework Equations The Attempt at a Solution I need help with (5) and (24). For (5), i can find MU and MV but have difficulty in finding MnU and MnV. For (24), i can solve (i) but don't know how to find (A+I)21B. The answer for (5): MnU=6nu; MnV=9nV... As for (24)...
  39. Char. Limit

    Understanding Matrices: Questions & Answers

    I have a few questions relating to matrices. 1. All of the matrices I've worked with so far dealt with real numbers or real functions of real numbers. Can you work instead in complex numbers, and do you have to add or remove any rules because of this? 2. All of the matrices I've worked...
  40. G

    Why are positive definite matrices useful?

    I've recently been learning about how to tell if a matrix is positive definite and how to create a positive definite matrix, but I haven't been given a reason why they're useful yet. I'm sure there are plenty of reasons, I just haven't seen them yet. In what ways do the properties of a positive...
  41. L

    Diagonalizable Matrices: What Values of a Make This Matrix Diagonalizable?

    Hey all, I have a question on this specific application of diagonalizable matrices. Homework Statement For what values of the real constant a is the matrix diagonalizable over \mathbb{C}? For what values is the matrix diagonalizable over \mathbb{R}? \begin{bmatrix} 0 & 0 & a\\ 1...
  42. T

    Matrices and number of solutions

    Q1. Find the value of a for which there are infinitely many solutions to the equations 2x + ay − z = 0 3x + 4y − (a + 1)z = 13 10x + 8y + (a − 4)z = 26 Now I know that for there to be infinitely many solutions the determinant of the coefficient matrix must = 0. I did this on a...
  43. R

    Find a basis for the space of 2x2 symmetric matrices

    a)Find a basis for the space of 2x2 symmetric matrices. Prove that your answer is indeed a basis. b)Find the dimension of the space of n x n symmetric matrices. Justify your answer.
  44. soothsayer

    Proof: Product of Orthogonal Matrices is Orthogonal

    Homework Statement Show that a product of orthogonal matrices is orthogonal.Homework Equations Orthoganol matrix: M-1=MTThe Attempt at a Solution since A-1=AT A-1 and AT commute. commutable => symmetric => A-1AT=(A-1AT)T (A-1AT)-1=A-1AT/det(A-1AT) => (A-1AT)-1(A-1AT)=(A-1AT)2/det(A-1AT)...
  45. M

    Transforming a line segment with matrices?

    Homework Statement If you have the matrix X = [ 1 1; 1 0] and Y = [ 0 -1; 1 0] and line segment A = {(0,y) | 0<y<1} Draw the images of line segment after you transform it by matrix X, Y, XY, YX (the image of A after transformation by linear transformation of L is {L(a) | all a in A} Homework...
  46. D

    Proving Real 2x2 Matrices are a Vector Space

    Homework Statement Show that all 2 x 2 matrices with real entries: M(2x2) = { a b | a,b,c,d are real numbers} c d | is a vector space under the matrix addition: |a1 b1| + | a2 b2| = |a1+a2 b1+b2| |c1 d1| + | c2 d2| = |c1+c2 d1+d2| and scalar multiplication: r*| a b | = | ra...
  47. H

    Proving Similarity of Matrices with Same Polynomials

    Homework Statement Let A and B be 3x3 matrices over a field F. Prove that A and B are similar if and only if they have the same characteristic polynomial and the same minimal polynomial. Homework Equations The Attempt at a Solution
  48. T

    Matrix Derivation: 2x1 A and B with Dimension and dA/dB Calculation

    Hi, I need help with matrix derivation. I have 2 matrices of dimension 2x1, A and B. A = [f(x) x]^{T} B = [y x]^{T} I would like to find the dA/dB. How do I do this? and what is the dimension of the resultant matrix?
  49. B

    Motivating Matrix Addition/Multiplication Without Appealing to Linear Maps

    Hi, Everyone: In linear algebra courses, the defs/formulas for the sum, multiplication of matrices respectively, are often motivated by the fact that matrix addition models the point-wise addition of linear maps, i.e., If A,B are linear maps described on the same basis, then the sum...
  50. S

    Linear dependence of square matrices

    I am studying the subject of linear dependence right now and had a question on this topic. Is it possible to construct a square matrix A such that the columns of A are linearly dependent, but the columns of the transpose of A are linearly independent? My intuition tells me no, but I'm not sure...
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