Eigenvalues Definition and 853 Threads

  1. G

    Finding Eigenvalues of Real Non-Symmetric Matrices

    Hi, Can somebody provide a link(other than numerical recipes) where I can get an optimized 'C' program for calculating eigenvalues of real nonsymmetric martix. Thanks
  2. R

    Eigenvalues and Eigenspinors: How to find them for the S_y matrix?

    [SOLVED] Eigenvalues and Eigenspinors Homework Statement (a) Find the eigenvalues and eigenspinors of S_{y}. Homework Equations \hat{Q}f(x) = \lambda f(x) The Attempt at a Solution The above equation wasn't given specifically for this problem; but that's the one I'm trying to...
  3. C

    Are there legal ways to quickly find eigenvalues of an operator?

    If I have an operator of the form 1+3\vec{e}\cdot\vec{\sigma} where \vec{e}\cdot\vec{e}=1. How can I find the eigenvalues quickly?
  4. pellman

    Can a Quantum State Have Time-Dependent Eigenvalues?

    Given an operator \hat{Q} (in the Schrodinger picture) in non-relativistic quantum mechanics and a state |\psi(t)\rangle such that \hat{Q} |\psi(t)\rangle=q(t)|\psi(t)\rangle where q(t) is explicitly time-dependent, can we properly say that |\psi(t)\rangle is an eigenstate of Q with a...
  5. E

    What are the eigenvalues of L operators?

    Hi Homework Statement We're given the operators Lx, Ly and Lz in matrix form and asked to show that they have the correct eigenvalues for l=1. Obviously no problem determining the values and Lz comes out right, however we've never actually seen the e.v.s for Lx and Ly. Homework...
  6. C

    Finding Eigenvalues with the Determinant Method

    Homework Statement I need the eigenvalues and eigenvectors of [[0,0,1][0,2,0][1,0,0]] The Attempt at a Solution How come when I use the determinent method to get the eigenvalues I only end up with 2? Did I make a mistake or is there some other way I'm supposed to find -1, +1?
  7. S

    Solving Polynomials with Degree <= 10: Finding Eigenvalues & Eigenspaces

    any ideas on how to go about conducting these please. i will attempt them once i have a clear idea on how to do this. thanks :) let V be the vector space of polynomials over C of degree <= 10 and let "D: V -----> V" be the linear map defined by D(f) = df/dx show (1) D^11=0 (2)...
  8. W

    Accuracy of finding eigenvalues of defective matrix

    Homework Statement Hi all, I need help with determining the accuracy of finding eigenvalues of defective matrix. The question asks: When a matrix has a defective eigenvalue, the condition number for computing its eigenvalues is infinity. Does this mean that these eigenvalues cannot be...
  9. F

    Eigenspaces, eigenvalues and eigenbasis

    Hey guys, I was wondering what the difference between a generalized eigenspace for an eigenvalue and just an eigenspace is. I know that you can get a vector space using an eigenbasis ie using the eigenvectors to span the space but apart from that I am kinda stumped. Also with regard to...
  10. Kudaros

    Transformations and eigenvalues

    Homework Statement Let A be the matrix of the linear transformation T. Without writing A, find an eigenvalue of A and describe the eigenspace. T is the transformation on R^3 that rotates points about some line through the origin. Homework Equations maybe...Ax=(lambda)x ? The Attempt...
  11. K

    Can q Have Eigenvectors Other Than Zero in Standard Quantization Procedure?

    In standard quantization procedure we should apply commutation rules [p,q]=i. But let's do a simple calculation: i \langle q_0 | q_0 \rangle = \langle q_0 | [p,q] | q_0 \rangle = \langle q_0 | pq | q_0 \rangle - \langle q_0 | qp | q_0 \rangle = q_0 \langle q_0 | p | q_0 \rangle - q_0 \langle...
  12. K

    Eigenvalues & Similar Matrices

    Q: Suppose the only eigenvalues of A are 1 and -1, and A is similar to a diagonal matrix. Prove that A^-1 = A My Attempt: Suppose the only eigenvalues of A are 1 and -1, and A is similar to a diagonal matrix. =>A is invertible (since 0 is not an eigenvalue of A) and there exists invertible...
  13. C

    MATLAB MATLAB Incorrectly Calculating Eigenvalues of Unitary Matrix

    This is a MATLAB question. I am trying to find the eigenvalues of a matrix with both real and complex numbers. This is my session. >> A=[1/sqrt(2),i/sqrt(2),0; -1/sqrt(2),i/sqrt(2),0; 0,0,1] A = 0.7071, 0 + 0.7071i, 0 -0.7071, 0 + 0.7071i, 0 0, 0...
  14. I

    SHO Eigenvalues with Non-Standard Potential

    We know the eigenvalue relation for the Hamiltonian of a SHO (in QM) though relating the raising and lowering operators we get: H= \hbar \omega (N+1/2) This is true for H=\frac{p^2}{2m}+\frac{m \omega^2 x^2}{2} I would like to solve for another case where V=a\frac{m \omega^2 x^2}{2} where...
  15. N

    All eigenvalues zero => zero map

    I want to prove that if all the eigenvalues of a linear transformation T : V --> V are zero, then T = 0. I think this is obvious but I'm having difficulty putting it into words. If all the eigenvalues of T are zero, then there exists a basis B for V in which [T]_B is the zero matrix. Thus...
  16. C

    Are There Integer Eigenvalues for a Specific Matrix?

    Homework Statement I need the eigenvalues of [[3, -1][-1, 1]] (ie [[row1][row2]]) The Attempt at a Solution A-xI = [[3-x, -1][-1, 1-x]] so I get the characteristic polynomial x^2-4x+2=0 from det(A-xI)=0 Is this correct? Because I won't get integer eigenvalues from it
  17. S

    Eigenvalues & Eigenfunctions: Exploring Physical Significance

    what is a eigen value and eigen function? i have read a lot abt it...i understand the math behind it.. what is its physical significance of it?
  18. W

    Calculating Eigenvalues: 0 Root Meanings

    This is just a general question: If, when you are calculating the eigenvalues for a matrix, you get a root of 0 (eg. x^3 - x) --> x(x-1)(x+1), what does that mean for the eigenvectors? thanks, w.
  19. E

    Energy eigenvalues and momentum distributions

    In the quantum version of the symmetric infinite well, the energy eigenvalues are, in principle, well-determined. Why would the momentum then have a spread or distribution for a given energy eigenvalue i.e. \phi(p) = 1/(2\pi\hbar) \int_{-a}^{a}dx u_n (x) e^{-ipx/\hbar} where u_n is the...
  20. E

    Eigenvectors, eigenvalues and matrices

    I have: x' = \left(\begin{array}{cc}2&-5\\1&-2\end{array}\right) x I found that the eigenvalues are r_1 = i and r_2 = - i. Also, I calculated the eigenvectors to be \xi_1 = \left(\begin{array}{c}2 + i\\1\end{array}\right) \xi_2 = \left(\begin{array}{c}2 - i\\1\end{array}\right)...
  21. C

    Find the eigenvalues of a matrix

    Homework Statement i'm trying to find the eigenvalues of a matrix and i have the solution but i don't understand how it gets from the step 1 to step 2? could someone please explain. let # = lambda Step 1: (1-#)[(2-#)(-1-#)+1]+[3(-1-#)+2]+4[3-2(2-#)] = 0 Step 2: (1-#)(#+2)(#-3) = 0...
  22. A

    Eigenvalues for a matrix with equal and opposite diagonal entries?

    Given a square matrix (arbitrary finite size) where two diagonal entries are 'a' and '-a', what can you derive about the eigenvalues of the matrix? My supervisor mentioned she'd read something about it being provable that the matrix cannot be positive or negative definite. Two of the...
  23. R

    Real Eigenvalues and 3 Orthogonal Eigenvectors for Matrix (c,d)

    Homework Statement For which real numbers c and d does the matrix have real eigenvalues and three orthogonal eigenvectors? 120 2dc 053 Homework Equations im having trouble getting started on this one. Ive tried using solving for the eigenvalues pretending that c and d are...
  24. P

    How do I estimate complex eigenvalues?

    Let A be a matrix with real elements. The problem is to estimate eigenvalues of A, real and complex. QR algorithm is fine for real eigenvalues, but obviously fails to converge on complex eigenvalues... So, I'm looking for an alternative that could provide an estimate for complex eigenvalues of...
  25. R

    Eigenvalues of operator between L^2

    Homework Statement >M: L_2 -> L_2 > >(Mf)(t) = int(-pi, pi) sin(y-x)f(x) dx > >how do i find eigenvalues/vectors of M and what can i use to find >information about the spectrum? Homework Equations The Attempt at a Solution now i know that sin(y-x) = sinycosx-cosysinx...
  26. P

    Eigenvalues for particle in finite square well

    I am a second year physics student and have been set a homework assignment to solve a one dimensional time independant schrodinger equation in a finite square well using microsoft excel. I understand the physics behind the situation but am not exactly sure how to use microsoft excel to solve...
  27. N

    Can All Eigenvectors of a Matrix Be Zero Vectors?

    Hi I came across a problem of eigenvalues and eigenvectors. It was easy and I solved it but one thing made me unsure about the answer. All the three eigenvectors were zero vectors. Here is the question and my answer: The matrix A= ( -1 0 0 1 0 -2 0 0 0 1 -2 0...
  28. V

    Eigenvalues + Algebraic/Geometric Multiplicity

    I'm studying for a linear algebra final, and I'm looking over an old final our prof gave us and I've come across something I don't remember ever hearing anything about... Here's the problem: Write down a matrix A for the following condition: A is a 3x3 matrix with lambda=4 with algebraic...
  29. S

    Eigenvalues and eigenvectors of a linear transform

    Homework Statement Find all the eigenvalues and eigenvectors of the linear transformation: T(f) = 5f ' -3f T: from C^(nfnty) --> C^(nfnty) where C^(nfnty) is set of continuously functions Homework Equations A scalar B is called an eigenvalue of T if there exists a nonzero element f...
  30. F

    Calculating eigenvalues and eigenstates

    Hi! i want to calculate the eigenvalues and the eigenstates of the momentum operator and the Hamilton operator of a free particle. How do i do this? Thanks for answers!
  31. K

    Eigenvalues And Eigenvectors Problems

    1. How to show (prove) the Cayley-Hamilton theorem : “Every matrix is a zero of its characteristic polynomial , Pa(A)=0”. 2. A and B are n-square matrices, show that AB and BA have the same eigenvalues. 3. Show that to say that “ 0is an eigenvalue of linear mapping U” is equivalent to “ U...
  32. N

    Proving UT and TU Have Same Eigenvalues

    Let U, T be linear operators on a vector space V. Prove that UT and TU have the same eigenvalues. Any ideas?
  33. J

    Are the Eigenvalues of a Unitary Operator of the Form e^i(a)?

    Homework Statement A unitary operator U has the property U(U+)=(U+)U=I [where U+ is U dagger and I is the identity operator] Prove that the eigenvalues of a unitary operator are of the form e^i(a) with a being real. NB: I haven't been taught dirac notation yet. Is there a way i can do...
  34. E

    Eigenvalues and eigenfunctions of the lowering operator

    Homework Statement Consider lowering and rising operators that we encountered in the harmonic oscillator problem. 1. Find the eigenvalues and eigenfunctions of the lowering operator. 2. Does the rising operator have normalizable eigenfunctions?Homework Equations a-= 1/sqrt(2hmw) (ip + mwx) a+...
  35. P

    Eigenvalues in QM: Find Out Why They Always Yield Same Value

    If after you apply an operator and hence calculate the expectation value of a measureable entity and if you get an eigenvalue, then does that mean when you do the measurement, you will always get the same value for that operator entity, each time? I think yes because otherwise what is so...
  36. W

    Eigenvalues of J_2 + K_1; -J_1 + K_2

    Weinberg in volume 1 of his QFT text says we do not observe any non-zero eigenvalues of A = J_2 + K_1; B = -J_1 + K_2. He says the "problem" is that any nonzero eigenvalue leads to a continuum of eigenvalues, generated by performing a spatial rotation about the axis that leaves the standard...
  37. A

    Hessian Matrix\Max Min Analysis, Eigenvalues etc

    In my calc 3 class, we've taken an alternative(?) route to learning maxes and mins of multivariable equations. By using a Hessian Matrix, we're supposed to be able to find the eigenvalues of a function at the point, and determine whether the point is a max, min, saddle point, or indeterminant...
  38. A

    How Do Eigenvectors of a Matrix Relate to Its Inverse?

    Suppose that B is the inverse of A. Show that if |psi> is an eigenvector of A with eigenvalue a not equal to 0, then |psi> is an eigenvector of B with eigenvalue 1/a. So I know that A|psi> = a|psi>, and I'm trying to prove that A^(-1)|psi> = 1/a|psi>. I tried simplifying A as a 2x2 matrix...
  39. D

    How Do Complex Eigenvalues Affect Numerical Solutions of PDE Systems?

    I'm currently researching a 3d tensor, where certain combinations of terms can cause the principal values (eigenvalues) to become complex. This would then seem to imply that the associated eigenvectors would also become complex. What now, if this tensor were part of a larger equation...
  40. S

    Find the Eigenvalues of the matrix and a corresponding eigenvalue

    Find the Eigenvalues of the matrix and a corresponding eigenvalue. Check that the eigenvectors associated with the distinct eigenvalues are orthogonal. Find an orthogonal matrix that diagonalizes the matrix. (1)\left(\begin{array}{cc}4&-2\\-2&1\end{array}\right) I found my eigenvalues to...
  41. S

    Conceptual Questions/Eigenvectors and Eigenvalues

    This is how the book introduced eigenvectors: I do not get how the normal vector of x-y = 0 is <1,-1> . Isn't that saying that the x-component is 1 and the y-component is -1? Also how did they get the vector equation <x,y> = t<1,-1> + <a,b> ? Finally, why does \vec{OQ} = \vec{OP}...
  42. F

    Are Linear Operators Commutative When They Share Common Eigen Vectors?

    If A & B are linear operators, and AY=aY & BY=bY, what is the relationship between A & B such that e^A*e^B=e^(A+B)?? --where e^x=1+x+x^2/2+x^3/3!+...+x^n/n!
  43. F

    Do Commuting Linear Operators A and B Satisfy the Exponential Property?

    If A & B are linear operators, and AY=aY & BY=bY, what is the relationship between A & B such that e^A*e^B=e^(A+B)?? --where e^x=1+x+x^2/2+x^3/3!+...+x^n/n!
  44. G

    Constructing Eigenvectors from Commuting Matrices: A Unique Classification

    Hey all, I have two matrices A,B which commute than I have to show that these eigenvectors provide a unique classification of the eigenvectors of H? From these pairs of eigenvalue is it possible to obtain the eigenvectors? I don't quite know how to procede any suggestions? Thanks...
  45. K

    What Are the Eigenvalues of a Hermitian Operator if \(\hat{A}^2 = 2\)?

    Hi again, Question: \hat{A} is an Hermitian Operator. If \hat{A}^{2}=2, find the eigenvalues of \hat{A} So We have: \hat{A}\left|\Psi\right\rangle=a\left|\Psi\right\rangle But I actually don't know how to even begin. \hat{A} is a general Hermitian operator, and I don't know where...
  46. G

    Eigenfunctions and their Eigenvalues

    If I have two eigenfunctions of an operator with the same eigenvalue how do I construct linear combinations of my eigenfunctions so that they are orhtogonal? My eigenfunctions are: f=e^(x) and g=e^(-x) and the operator is (d)^2/(dx)^2
  47. J

    How can I calculate the eigenvalues of a Hamiltonian with spin 1/2 objects?

    Find the eigenvalues of the hamiltonian H=a(S_A \cdot S_B+S_B \cdot S_C+S_C \cdot S_D+S_D \cdot S_A) where S_A, S_B, S_C, S_D are spin 1/2 objects _________________________ I rewrite it as H=(1/2)*a*[(S_A+S_B+S_C+S_D)^2-(S_A+S_C)^2-(S_B+S_D)^2] then i define...
  48. G

    Are Eigenkets with Eigenvalues Periodic for a Hamiltonian System?

    Hey, A Hamiltonian has 3 eigenkets with three eigenvalues 1, sqrt(2) and sqrt(3) - will the expectation values of observables in general be period functions of time for this system? I don't know how to procede? Thnaks in advance
  49. B

    Diagonalization of a matrix with repeated eigenvalues

    Hey guys, I know its possible to diagonalize a matrix that has repeated eigenvalues, but how is it done? Do you simply just have two identical eigenvectors?? Cheers Brent
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