Basis Definition and 1000 Threads

  1. D

    How to Represent |+x> and |-x> Using |+y> and |-y> as Basis?

    Homework Statement Determine the column vectors representing the states |+x> and |-x> using the states |+y> and |-y> as a basis. Homework Equations ? The Attempt at a Solution The hint my prof gave us was that since |+x> = 1/√2|+z> + 1/√2|-z> we can eliminate the states |+z> and...
  2. A

    How to find a basis for the vector space of real numbers over the field Q?

    So the title says everything. Let's assume R is a set equipped with vector addition the same way we add real numbers and has a scalar multiplication that the scalars come from the field Q. I believe the dimension of this vector space is infinite, and the reason is we have transcendental numbers...
  3. F

    Dot product between arrays: basis representation of an image

    Hello Forum, When we represent a vector X using an orthonormal basis, we express X as a linear combination of the basis vectors: x= a1 v1 + a2 v2 + a3 v3+ ... Each coefficient a_i is the dot product between x and each basis vector v_i. If the vector x is not a row (or column vector)...
  4. D

    Proving Existence of Basis in Vector Spaces

    Hi, I've been trying to prove that every vector space has a basis. So starting from the axioms of vector space I defined linear independence and span and then defined basis to be linear independent set that spans the space. I was trying to figure out a direct way to prove the existence of...
  5. B

    How Do You Write the Wavefunction for Two Electrons in Quantum States?

    Homework Statement This is something I should know, but I keep getting mixed up when I try to think about it. A quantum state can be written as a superposition of basis states such as \left | n \right \rangle So let's say I have a particle in a potential with discrete energy levels...
  6. B

    Is it possible to define a basis for the space of continuous functions?

    In analogy to vector spaces, can we define a set of "basis functions" from which any continuous function can be written as a (possibly infinite) linear combination of the basis functions? I know the trigonometric functions 1, sin(nx), cos(nx) can be used for monotonic continuous functions...
  7. P

    Is matrix A in the form of RREF?Is Matrix A in RREF form?

    I attached 2 problems. For problem #1. I want to make sure I'm on the right track, to find the span of Null(A), i need to put matrix A in RREF form. By doing so I get x1=-2t x2=-t x3=s x4=u (using u because I'm using t to denote transpose) where x1 to x4 is for each respective column...
  8. A

    A question about linear algebra (change of basis of a linear transformation)

    Homework Statement Let A \in M_n(F) and v \in F^n. Let v, Av, A^2v, ... , A^{k-1}v be a basis, B, of V. Let T:V \rightarrow V be induced by multiplication by A:T(w) = Aw for w in V. Find [T]_B, the matrix of T with respect to B. Thanks in advance Homework Equations...
  9. D

    Understanding basis and dimension

    I am really confused about something. I know that if I have a vector space, then the dimension of that vector space is the number of elements in a basis for it. But this brings up some confusing issues for me. For example, if we are looking at the null space of a non-singular, square matrix...
  10. ElijahRockers

    Find a basis for a set S of R4

    Homework Statement Find a basis for the subspace S of vectors (A+B, A-B+2C, B, C) in R4 What is the dimension of S? The Attempt at a Solution Do I just plug in varying values for A B and C to create four vectors, and see if they are linearly independent? If they are then I've found...
  11. N

    The basis of the Real numbers over the Irrationals

    1. What can be said of the dimension of the basis of the Reals over the Irrationals 2. Homework Equations 3. I believe the basis is infinite because any real number can be made out of the combination of irrational vectors multiplied by the same irrational coefficient to make any real number...
  12. S

    Lineal Transformation basis change

    Find http://imageshack.us/a/img35/1637/lineal2.gif http://imageshack.us/a/img210/1370/lineal1.gif C^3 is the canonical base of ℝ^3, C^2 is the canonical base of ℝ^2 I tried: http://imageshack.us/a/img822/6274/lineal3.gif But I'm not sure if this is right, I made a...
  13. T

    Finding a basis for a set of polynomials and functions

    Find a basis for and the dimension of the subspaces defined for each of the following sets of conditions: {p \in P3(R) | p(2) = p(-1) = 0 } { f\inSpan{ex, e2x, e3x} | f(0) = f'(0) = 0} Attempt: Having trouble getting started... So I think my issue is interpreting what those sets...
  14. K

    Non-coordinate basis for vector fields

    Hello! Im trying to read some mathematical physics and have problems with the understanding of vector fields. Th questions are regarding the explanations in the book "Geometrical methods of mathematical physics".. The author, Bernard Schutz, writes: "Given a coordinate system x^i, it is often...
  15. fluidistic

    Completing the basis of a matrix, Jordan form related

    Hi guys, Let's say I have a 6x6 matrix A whose Jordan form J has 3 Jordan blocks. It means that this matrix (matrix A, but I think that also the matrix J) has 3 linearly independent eigenvectors, I have no problem in finding them. I simply do (A-\lambda _i I)v_i=0 to get the eigenvectors v_i...
  16. C

    Basis of a subspace and dimension question

    How do i go about this? Find a basis for the subspace W of R^5 given by... W = {x E R^5 : x . a = x . b = x . c = 0}, where a = (1, 0, 2, -1, -1), b = (2, 1, 1, 1, 0) and c = (4, 3, -1, 5, 2). Determine the dimension of W. (as usual, "x . a" denotes the dot (inner) product of the...
  17. H

    Understanding Basis Vectors and One-Forms: A Simplified Explanation

    Greetings, I have just started studying manifolds, and have come across the idea that the basis vectors can be expressed as: e\mu = \partial/\partialx\mu. I tried to convince myself of this in 2D Cartesian coordinates using a pretty non-rigorous derivation (the idea being to get a...
  18. Alesak

    Don't understand continuous basis

    Hi, I'm beginning to learn QM, and I've never seen any treatment of vector spaces with infinite bases. Countable case is quite digestible, but uncountable just flies over my head. Can anyone recommend me place where to learn this more advanced part of linear algebra, with focus on stuff...
  19. O

    What do engineers do on a daily basis?

    I am pretty sure I want to go into engineering, but I am really curious as to what engineers do on a daily basis. I have this vague and somewhat childish idea that it is just a bunch of people in overalls tinkering with machine parts. That just shows how little I really know. I'm looking for...
  20. C

    Finding a basis of eigenvectors

    Homework Statement A = \left( \begin{array}{ccc} 2 & 0 & -1 \\ 4 & 1 & -4 \\ 2 & 0 & -1 \end{array} \right) Find the eigenvalues and corresponding eigenvectors that form a basis over R3 Homework Equations The Attempt at a Solution OK so I've found the characteristic...
  21. J

    Linear transformation and Change of Basis

    Homework Statement Greetings, I have been stuck with this problem for a while, I thought maybe someone could give me some advice about it. Thanks a lot in advance. If T is a linear transformation that goes from R^2 to R^2 given that T(v1)= -2v2 -v1 and T(v2)=3v2. and B =...
  22. V

    Basis for an irreducible representation

    Homework Statement I'm having trouble understanding a concept in representation theory. I've been reading several texts on the application of rep. theory to quantum mechanics ("Group Theory and Quantum Mechanics" by Tinkham and "Group Theory and Its Application to Physical Problems" by...
  23. C

    What Basis Spans Square Integrable Functions with Exponential Tails on [0,∞)?

    Hi, I have a function on [0,\infty) which is represented as: \sum_{ \stackrel{ \Re( \alpha )\in\mathbb{Q}^+ }{ \Im( \alpha )\in\mathbb{Q} } }{\beta_\alpha e^{-\alpha t}} It seems like this must be a basis for the square integrable functions on [0,\infty) with exponential tails. Am I right...
  24. G

    Find a basis of a subspace of R^4

    Find a basis of the given span{[2,1,0,-1],[-1,1,1,1],[2,7,4,5]} So I got the RREF, and found the basis to be two rows of the RREF, which are [1,0,-1/3,0] and [0,1,2/3,1], but the answer is [2,1,0,-1],[-1,1,1,1] Where did I do wrong?
  25. M

    I am not sure - a manifold is locally connected and has countable basis?

    I am not sure -- a manifold is locally connected and has countable basis? There is an Exercise in a book as following : Given a Manifold M , if N is a sub-manifold , an V is open set then V \cap N is a countable collection of connected open sets . I am asking why he put this exercise...
  26. matqkks

    Unlock the Power of Basis Vectors: Impactful Examples

    I have normally introduced basis vectors by just stating independent vectors that span the space. This is perhaps not very inspirational. What is attractive way to introduce basis vectors? I am looking for a hook that students will find motivating. It needs to have an impact. Maybe a good...
  27. matqkks

    MHB How Can Basis Vectors Simplify Real-World Problems?

    What is attractive way to introduce basis vectors? I am looking for a hook that students will find motivating. It needs to have an impact. I have normally introduced it by just stating independent vectors that span the space.
  28. M

    Riemann tensor cyclic identity (first Bianchi) and noncoordinate basis

    I got trouble to understand the cyclic sum identity (the first Bianchi identity) of the Riemann curvature tensor: {R^\alpha}_{[ \beta \gamma \delta ]}=0 or equivalently, {R^\alpha}_{\beta \gamma \delta}+{R^\alpha}_{\gamma \delta \beta}+{R^\alpha}_{\delta \beta \gamma}=0. I can understand the...
  29. A

    What Am I Missing in Change of Basis Matrices?

    Homework Statement https://dl.dropbox.com/u/4788304/Screen%20shot%202012-07-08%20at%2002.53.44.JPG This is the solution of Problem A.15 in Griffiths' Quantum Mechanics. Tx is the rotation matrix about x-axis for theta degrees; while Ty is the rotation matrix about y-axis for theta degrees...
  30. M

    Modern physics basis for magnetic properties of matter

    Do you people know any decent and simple (no fancy math) material for the atomic physics around diamagnetism, paramagnetism and ferromagnetism? Topics like wave-particle duality, energy levels, solids, why metals are conductors, relation between magnetic moment and effective mass of...
  31. PerpStudent

    Is there an intuitive basis for the Lagrangian?

    Since it is based on the kinetic energy less the potential energy, what does the Lagrangian actually represent? Is there some intuitive way to understand why it is defined so and why it is such a fruitful concept using the principle of least action?
  32. O

    Linear Algebra - Jordan form basis

    Hi all, I'm having trouble finding jordan basis for matrix A, e.g. the P matrix of: J=P^{-1}AP Given A = \begin{pmatrix} 4 & 1 & 1 & 1 \\ -1 & 2 & -1 & -1 \\ 6 & 1 & -1 & 1 \\ -6 & -1 & 4 & 2 \end{pmatrix} I found Jordan form to be: J = \begin{pmatrix} -2 & & & \\ & 3 & 1 & \\ & & 3 &...
  33. B

    Why Does the Second Equality Hold in Multi-Linear Algebra?

    {(a_i)_j} is the dual basis to the basis {(e_i)_j} I want to show that ((a_i)_1) \wedge (a_i)_2 \wedge... \wedge (a_i)_n ((e_i)_1,(e_i)_2,...,(e_i)_n) = 1 this is exercise 4.1(a) from Spivak. So my approach was: \BigWedge_ L=1^k (a_i)_L ((e_i)_1,...,(e_i)_n) = k! Alt(\BigCross_L=1^k...
  34. K

    Pseudoinverse - change of basis?

    Hello, I was wondering if the pseudoinverse can be considered a change of basis? If an m x n matrix with m < n and rank m and you wish to solve the system Ax = b, the solution would hold an infinite number of solutions; hence you form the pseudoinverse by A^T(A*A^T)^-1 and solve for x to...
  35. H

    Find a kernel and image basis of a linear transformation

    Homework Statement Find a kernel and image basis of the linear transformation having: \displaystyle T:{{\mathbb{R}}^{3}}\to {{\mathbb{R}}^{3}} so that \displaystyle _{B}{{\left( T \right)}_{B}}=\left( \begin{matrix} 1 & 2 & 1 \\ 2 & 4 & 2 \\ 0 & 0 & 0 \\ \end{matrix} \right)...
  36. T

    If V is a 3-dimensional Lie algebra with basis vectors E,F,G

    If V is a 3-dimensional Lie algebra with basis vectors E,F,G with Lie bracket relations [E,F]=G, [E,G]=0, [F,G]=0 and V' is the Lie algebra consisting of all 3x3 strictly upper triangular matrices with complex entries then would you say the following 2 mappings (isomorphisms) are different? I...
  37. L

    Does every independent set spans the space necessarily form a basis?

    Hi there! A Hilbert space E is spanned by a set S if E is generated by the element of S. It is well known that in the finite dimensional case that S spans E and S is linearly independent set iff the set S form a basis for E. The question is that true for the infinite dimensional...
  38. H

    Orthogonal Basis for a subspace

    Homework Statement Let W = \begin{cases} \begin{pmatrix}x\\y\\z\\w\end{pmatrix} \in R^4 | w + 2x + 2y + 4z = 0 \end{cases} A)Find basis for W. B)Find basis for W^{\perp} C)Use parts (A) and (B) to find an orthogonal basis for R^4 with respect to the Euclidean inner product. Homework...
  39. B

    Circular coordinate space using an orthonormal basis

    If we have any two orthonormal vectors A and B in R^2 and we wish to describe the circle they create under rigid rotation (i.e. they rotate at a fixed point and their length is preserved), how can we describe any point along this (unit) circle using a linear combination of A and B? I was...
  40. H

    Finding a matrix with respect to standard basis

    Homework Statement Homework Equations ... The Attempt at a Solution Can someone just point me how to approach this? Do we take a random second degree polynomial and input 2x + 3 instead of x, then find the constants (eg. denoted by a , b , c) by putting the new equation equal to...
  41. I

    Subspace as a Direct Sum of Intersections with Basis Partition?

    I've been working on this Linear Algebra problem for a while: Let F be a field, V a vector space over F with basis \mathcal{B}=\{b_i\mid i\in I\}. Let S be a subspace of V, and let \{B_1, \dotsc, B_k\} be a partition of \mathcal{B}. Suppose that S\cap \langle B_i\rangle\neq \{0\} for all i...
  42. H

    Basis and Dimension of a Subpace.

    Homework Statement V = {p(x) belongs to P3 such that p'(1) + p'(-1) = 0} Homework Equations ... The Attempt at a Solution Okay, so finding the first derivative of p(x) = ax^3 + bx^2 + cx + d and plugging in the values 1 and -1 (to find p'(1) and p'(-1)), we get c = -3a. Does this make the...
  43. J

    Finding a basis in ImT using Gaussian Elimination

    Homework Statement $$ \begin{pmatrix} -1&3&0\\ 2&0&-1\\ 0&-6&1 \end{pmatrix} $$ Finding the ImT basis of this The Attempt at a Solution I got it down to $$ \begin{pmatrix} 1&0&-1/2\\ 0&1&1/6\\ 0&0&1 \end{pmatrix} $$ I know that by the principle of having pivots as the only non-zero...
  44. S

    Undergraduate Mechanics (Problem with force expressed as basis vectors)

    Homework Statement The problem along with its solution is attached as Problem 1-2.jpg. Homework Equations Norm of a vector. The Attempt at a Solution Starting from the final answer of the solution, sqrt((-0.625)^2 + (0.333)^2) == 0.708176532 != 1. Did the book do something wrong? I ask...
  45. A

    Finding basis of a column space/row space

    I was wondering whether we can use row as well as column operations to reduce a matrix to find column space? Or do we only have to perform row operations to reduce matrix in case of row space and column operations to find column space?
  46. R

    Determine whether the given vectors form a basis

    Homework Statement w1 = 2 1 2 w2 = 1 -2 -3 w3 = 5 0 1 for R3 Homework Equations The Attempt at a Solution The books says the above is not a basis, why not? There are no free variables, none of the vectors are multiples of the other, they are linearly independent and the...
  47. A

    Determinats,dependence, span, basis.

    Im having trouble under stand the relationships between determinats, span, basis. Given a 3x3 matrix on R3 vector space. * If determinat is 0, it is linearly dependent, will NOT span R3, is NOT a basis of R3. , If determinant is non-zero, its linearly independent, will span R3, is a basis of...
  48. K

    How can a basis in a vector space be used to determine linear independence?

    From what I understand, a basis is essentially a subset of a vector space over a given field. Now what I'm not so sure of is the linearly independence part. If the basis has two linearly independent vectors, then than means they aren't collinear: rather, they wouldn't have the same slope...
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