Inner product Definition and 312 Threads

  1. A

    Inner product of random Gaussian vector

    Hi, I would like to ask a question please. Assume we have a random vector X that is distributed under the Gaussian model and take the inner product of this vector and another constant vector d. Will the source distribution (Gaussian) remain the same? My intuition (although I might be...
  2. M

    Exploring Geometrical Implications of Inner Product Spaces

    The motivation for inner product spaces is geometric, yet I find myself a bit unclear about the geometrical implications associated with inner products. I would appreciate if some of my concerns could be addressed; while the length of my inquiry may be a bit much, I would like to make it clear...
  3. V

    Proving a function is an inner product

    Homework Statement I'm supposed to show that a function is an inner product if and only if b^2 - ac < 0 and a > 0. I have proven all of the properties except that <x,x> > 0 if x!= 0. I would write the function out, but can't seem to get matrices to work. The function is the...
  4. K

    Real inner product spaces and self adjoint linear transformations

    Homework Statement Let V be a real inner product space of dimension n and let Q be a linear transformation from V to V . Suppose that Q is non-singular and self-adjoint. Show that Q−1 is self-adjoint. Suppose, furthermore, that Q is positive-definite (that is, <Qv,v> > 0 for all non-zero...
  5. H

    Completeness of an inner product space

    I'm on a course which is currently introducing me to the concept of Hilbert spaces and the professor in charge was giving examples of such spaces. He ended by considering V, the space of polynomials with complex coefficients from \mathbb{R} to \mathbb{C}. He then, for f,g\in V, defined...
  6. moe darklight

    Linear Algebra question using Evaluation Inner Product Points

    Question from my last LA.II assignment. I have no idea what to with it. It looked simple but now I think I don't even understand the question. Homework Statement Consider the Inner Product Space P2 with the evaluation inner product at points x0=-1, x1=0, and x2=2, and consider the subspace...
  7. A

    General form of an inner product on C^n proof

    Hi, I read that the general form of an inner product on \mathbf{C}^n is: \langle \vec{x} , \vec{y} \rangle = \vec{y}^* \mathbf{M} \vec{x} I see that it has what it takes to be an inner product, but it seems quite hard to demonstrate that this is the general form. Is there such a...
  8. J

    Proving Double Inner Product of Derivative of 2nd Order Tensor w/ Another

    Some one please help me how to prove the following: \dot{A}:B + A:\dot{B}=A^{\nabla J}:B+A:B^{\nabla J} A and B are II order tensors and : represents the inner product.
  9. A

    Question about inner product spaces

    Suppose you have an inner product space V (not necessarily finite dimensional; so it could be an infinite dimensional Hilbert space or something). Fix a vector \Phi in this space. Given an arbitrary vector \Psi \in V, can I write it as \Psi = \Psi^{\parallel} + \Psi^{\perp}, where...
  10. K

    Differing definitions of an inner product

    Hey all, This might seem like a stupid question, and this might not be the correct forum, but hopefully someone can clarify it really easily. I often have seen two definitions of an inner product on a vector space. Firstly, it can be defined as a bilinear map on a \mathbb F-vector space V...
  11. J

    Inner Product and Linear Transformation

    Homework Statement Let V be a finite-dimensional real inner product space with inner product < , >. Let L:V->R be a linear map. Show that there exists a vector u in V such that L(x) = <x,u> for all x in V. 2. The attempt at a solution It seems really simple but I just can't phrase...
  12. L

    A More Abstract Definition of an Inner Product Space?

    An inner product space is often simply described as a vector space with the addition of an inner product, but when it comes to the formal definition, the basefield seems to always be restricted to the fields of real and complex numbers. The Wikipedia article on inner product spaces remarks that...
  13. S

    Simple dot product [inner product] (verification)

    Homework Statement Homework Equations know dot product The Attempt at a Solution PART A PART B not sure what's it asking for help would be great
  14. B

    An inner product must exist on the set of all functions in Hilbert space

    Homework Statement Show that \int {{f^*}(x)g(x) \cdot dx} is an inner product on the set of square-integrable complex functions. Homework Equations Schwarz inequality: \left| {\int {{f^*}(x)g(x) \cdot dx} } \right| \le \sqrt {\int {{{\left| {f(x)} \right|}^2} \cdot dx} \int {{{\left|...
  15. M

    Problem With Explanation of Inner Product of Vector and Dyad

    I've been trying to learn more about tensors with the help of this website, http://www.grc.nasa.gov/WWW/k-12/Numbers/Math/documents/Tensors_TM2002211716.pdf, but its explanation on one little part about vectors has me puzzled. It states that an inner product of a vector S and a dyad expressed...
  16. M

    Inner Product Space/Hilbert Space Problem

    Homework Statement 3. If z is any fixed element of an inner product space X, show that f(x) = <x,z> defines a bounded linear functional f on X, of norm ||z||. 4. Consider Prob. 3. If the mapping X --> X' (the space of continuous linear functionals) given by z |--> f is surjective, show that X...
  17. H

    Proving Inner Product Spaces: Proving x=y if <x,z> = <y,z>

    Homework Statement Let \beta be a basis for a finite dimensional inner-product space. b) Prove that is < x, z > = < y, z> for all z \in \beta, then x = y Homework Equations The Attempt at a Solution start with the Cauchy-Schwarz: |< x, z >| \leq ||x|| ||z|| then because <x,z>...
  18. H

    Inner Product Spaces: Normal & Self Adjoint?

    An inner product space can be both normal and self adjoint, correct?
  19. R

    Linear Algebra, Inner Product of Matrices

    Let M_2x2 denote the space of 2x2 matrices with real coeffcients. Show that (a1 b1) . (a2 b2) (c1 d1) (c2 d2) = a1a2 + 2b1b2 + c1c2 + 2d1d2 defines an inner product on M_2x2. Find an orthogonal basis of the subspace S = (a b) such that a + 3b - c = 0 (c d) of M_2x2...
  20. H

    Inner product as integral, orthonormal basis

    Homework Statement Define an inner product on P2 by <f,g> = integral from 0 to 1 of f(x)g(x)dx. find an orthonormal basis of P2 with respect to this inner product. Homework Equations So this is a practice problem and it gives me the answer I just don't understand where it came from...
  21. S

    Inner product with (1,1) tensors: Diff. Geometry/ Lin algebra

    Homework Statement Given g\equiv g_{ij} = [-1 0; 0 1] Show that A= A^{i}_{j} = [1 2 -2 1] is symmetric wrt innter product g, has complex eigenvalues, but eigenvectros have zero length wrt the complex inner product. The Attempt at a Solution Im sure this is just a simple...
  22. X

    Why Don't All Inner Products Define the Same Vector Norm?

    I am having difficulties with understanding some aspects of inner products. For example, ||u||² = <u,u> Where <u,u> denoted the inner product of "u" with itself. My problem here is that we can define any inner product we wish. For example, if I defined, <u,v> = u1v1 + 3(u2v2) Then...
  23. E

    Why Does (u,v) = -u2v2 Not Qualify as an Inner Product in R2?

    Homework Statement State why (u,v) is not an inner product for u=(u1,u2) and v=(v1,v2) in R2 (u,v)=-u2v2 Homework Equations (u,v)=(v,u) c(u,v)=(cu,v) (v,v)=>0 and (v,v)=0 if only if v=0 The Attempt at a Solution I am having trouble understanding this problem and how to start it...
  24. G

    Inner Product of a Linear Transformation

    Homework Statement Let V be a vector space over a field F = R or C. Let W be an inner product space over F. w/ inner product <*,*>. If T: V->W is linear, prove <x,y>' = <T(x),T(y)> defines an inner product on V if and only if T is one-to-one Homework Equations What we know, W is an inner...
  25. D

    How Do I Resolve Cyclical Issues in Integration by Parts for Laplace Transforms?

    Last two inner product questions. The first one I am little confused on and the second one I don't know what to do. See worked attached.
  26. D

    Part C of the inner product problem

    I have attached the solutions of parts a, b, and what I have done for part c. My part c isn't going to turn out correct and I don't know what is wrong.
  27. D

    Angle Between 1 and x in C[0,1] Using Inner Product (3)

    In C[0,1], with inner product defined by (3), consider the vectors 1 and x. Find the angle theta between 1 and x. (3)\int_{0}^{1}f(x)g(x)dx Find the angle theta between 1 and x I don't know what to do with polynomial inner product vector space
  28. S

    Inner Product Definitions Galore?

    Hello, I thought I understood the Dot Product but Apparently Not! \overline{u} \ \cdot \ \overline{v} \ = (u_x \ \cdot \ v_x) ( \overline{i} \cdot \overline{i} ) \ + \ (u_y \ \cdot \ v_y) ( \overline{j} \cdot \overline{j} ) \ = \ | \overline{u} | | \overline{v} | cos \theta That is the...
  29. M

    Quick Inner Product Space Question

    Is the first part of this question saying find a scalar a such that \int_{-1}^1 \! a^{2} \, dx \, =1 \,? In that case I believe 1/20.5 is an answer...or am I reading the notation wrong? Thanks.
  30. V

    Inner product of Hilbert space functions

    this question is in reference to eq 3.9 and footnote 6 in griffith's intro to quantum mechanics consider a function f(x). the inner product <f|f> = int [ |f(x)|^2 dx] which is zero only* when f(x) = 0 only points to footnote 6, where Griffith points out: "what about a function that is...
  31. L

    Is the Inner Product for Dirac Spinors Antisymmetric?

    Homework Statement Show that \psi (\gamma^a\phi)=-(\gamma^a\phi)\psi Homework Equations Maybe \{\gamma^a, \gamma^b\}=\gamma^a\gamma^b+\gamma^b\gamma^a=2\eta^{ab}I Perhaps also: (\gamma^0)^{\dag}=\gamma^0 and (\gamma^i)^{\dag}=-(\gamma^i) The Attempt at a Solution The gammas are...
  32. S

    A basic qn on the inner product of a vector with an infinite sum of vectors

    A basic qn:An infinite sum of vectors will also be a vector in the same vector space? By definition, the sum of any two vectors of a vector space will be a vector in the same vector space. But does this mean the sum of an uncountable or countable number of vectors will also be a vector in the...
  33. S

    Understanding Double Inner Product Calculation in Multivariable Calculus

    Hi, I'm having trouble understanding how to perform the following calculation: u=(u,v,w) (\nabla u + (\nabla u)^T) : \nabla u I get the following by doing the dot product of the first term and then adding the dot product of the second term, but I'm pretty...
  34. L

    Maple Computing Inner Product of f_1 Using Maple Procedure

    so I'm writing a maple procedure for the variational principle in quantum mechanics. i have a function f_1(x,\alpha)=\cos{\alpha x} for |x| \leq \frac{\pi}{2 \alpha} and i need to compute \left \langle f_1 | f_1 \right \rangle i have the code: restart; assume(x,real)...
  35. S

    Bilinear maps and inner product

    Homework Statement We are given a linear map f, f:R2xR2->R. f has the following properties: 1)It is linear for the changes of the first variable 2)It is linear for the changes of the second variable 3)f((3,8),(3,8))=13 We are asked to say if f is anyhow related to the normal inner...
  36. I

    What Are Shankar's Inner Product Axioms in Quantum Mechanics?

    I was reading "Principles of Quantum Mechanics" - Shankar, and I'm having trouble understanding the inner product. Can someone help me or link me to a site that explains it? The axioms of the inner product are 1. \langle V|W\rangle = \langle W|V\rangle^* 2. \langle V|V\rangle \geq 0\ \...
  37. H

    Inner Product Spaces: Testing on C3

    Hey guys, In one of the questions for our assignment we have to decide whether <v,w> = v^{}TAw (with a conjugate bar over w) defines an inner product on C3. We are given three 3x3 marices to test this. What is the procedure for doing this? Do we just give w and v values such as a1, a2, a3...
  38. L

    Finding the inner product formulla

    once i solve that one is the derivative of the other but here its much harder to guess the formulla http://i47.tinypic.com/ixt74i.jpg what is the general method?
  39. P

    Inner Product (Infinite Dimensional)

    I am trying to understand the definition of the inner product of two functions on an interval. I know that the form of a scalar product in finite dimensional space is given by \vec{\phi} \bullet \vec{\psi}= \sum_{k} \phi_{k} \psi_{k} and in infinite dimensional space \langle \phi , \psi...
  40. G

    Inner Product of Polynomials: f(x) & g(x)

    Homework Statement Define the inner product of two polynomials, f(x) and g(x) to be < f | g > = ∫-11 dx f(x) g(x) Let f(x) = 3 - x +4 x2. Determine the inner products, < f | f1 >, < f | f2 > and < f | f3 >, where f1(x) = 1/2 , f2(x) = 3x/2 and f3(x) = 5(1 - 3 x2)/4 Expressed as a...
  41. J

    Proving Inner Product Space: x not in W, y in W(perp)

    Let V be an inner product space, and let W be a finite-dimensional subspace of V. If x\notin W, prove that there exists y\in V such that y \in W(perp), but <x,y>\neq 0. I don't have a clue... Thanks
  42. B

    Proving Inner Product Spaces: The Case of Real Polynomials of Degree 2

    Homework Statement We consider P2 the vector space of all real polynomials of degree at most 2. Show that <f,g> = \int_{-1}^{1}f(x)g(x)dx defines an inner product space Homework Equations I'm Using one of the Axioms of Inner product spaces IP1. which states that. <u,u>...
  43. M

    Determining Inner Product for P2: Non-Negativity, Symmetry & Linearity

    Hi, I was wondering how would i determine if <p,q> = p(0)q(0)+ p(1)q(1) is an inner product for P2. I know, we have to check for non-negativity, symmetry and linearity. Just not sure how. thanks!
  44. A

    Inner Product Spaces of 2x2 Matrix

    Homework Statement Show that <U,V> = u1.v1 + u2.v3 + u2.v3 + u4.v4 is NOT an inner product on M2x2Homework Equations U: row 1 = [u1 u2] row 2 = [u3 u4] V: row 1 = [v1 v2] row 2 = [v3 v4] The Attempt at a Solution As I went through each of the axioms, I found that they were all correct...
  45. P

    Finding Magnitude of v+iw in a Complex Inner Product Space

    Homework Statement Let v,w be vectors in a complex inner product space such that ||v|| = 1, ||w|| = 3 and <v,w> = 1 + 2i. Find ||v + iw||. Homework Equations The properties of an inner product. The Attempt at a Solution I figured ||v+iw||^2 = <v+iw,v+iw> Then using the...
  46. Y

    Fourier Analasys - Inner Product Spaces

    Homework Statement I have two assignments I have some problems with. The first one: For n > 0, let fn(t) = {1, 0 \leq t \leq 1/n 0, otherwise Show that fn \rightarrow 0 in L2[0,1]. Show that fn does NOT converge to zero uniformly on [0,1] The second one: Find...
  47. S

    Proof of inner product for function space

    Hi I am kinda new to this topic two . I was wondering how can I prove that the following expressions define scalar product. All I can guess that I need to show that they follow the properties of the scalar product. But how? If possible, help me with an example .1. (f,g)=\int f(x)g(x)w(x)dx...
  48. R

    Hermitian inner product btw 2 complex vectors & angle btw them

    What is the relationship btw the Hermitian inner product btw 2 complex vectors & angle btw them. x,y are 2 complex vectors. \theta angle btw them what is the relation btw x^{H}y and cos(\theta)?? Any help will be good?
  49. J

    Linear Algebra - Inner Product Spaces

    Homework Statement http://img199.imageshack.us/img199/3230/mathquestion2.png Thank you very much in advance! EDIT: subspace U = span(1,t)
  50. E

    Proof about inner product spaces

    Homework Statement Suppose V is a real inner-product space and (v1, . . . , vm) is a linearly independent list of vectors in V. Prove that there exist exactly 2^m orthonormal lists (e1, . . . , em) of vectors in V such that span(v1, . . . , vj) = span(e1, . . . , ej) for all j ∈ {1, . . . ...
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