Orthogonal Definition and 583 Threads

In mathematics, orthogonality is the generalization of the notion of perpendicularity to the linear algebra of bilinear forms. Two elements u and v of a vector space with bilinear form B are orthogonal when B(u, v) = 0. Depending on the bilinear form, the vector space may contain nonzero self-orthogonal vectors. In the case of function spaces, families of orthogonal functions are used to form a basis.
By extension, orthogonality is also used to refer to the separation of specific features of a system. The term also has specialized meanings in other fields including art and chemistry.

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  1. J

    Orthogonal vector spaces and matrices

    Hi everyone, I would need to get some help on the following question Let A (m*n) Let B (m*p) Let L(A) be the span of the columns of A. L(A) is orthogonal to L(B) <=> A'B=0 I suppose that the => direction is pretty obvious, since A is in L(A) and B in is L(B). Now I am not sure how to...
  2. M

    How Do Orthogonal Projectors Influence Dimensions and Norms?

    Let P and Q be two m x m orthogonal projectors. We show a) ||P-Q||_2 <or eq. 1 b)||P-Q||_2 < 1 implies the ranges of P and Q have equal dimensions. I think I must use the properties of orthogonal projectors. I guess Range(P) Inters Null(P) = {0} and Range(Q) Inters...
  3. T

    Finding a unit vector orthogonal to

    Homework Statement Find a unit vector that is orthogonal to both i + j and i + k. I know I can solve this using the cross product of the two. But This chapter is about dot product and not cross product. I am not sure how I could go about solving this problem using the properties of...
  4. M

    Finding the Orthogonal Trajectory for a Family of Curves

    Homework Statement i want to get the orthogonal trajectory of the curves of this family x^2 + y^2=cx Homework Equations answer is given as : y^2 + x^2=cy The Attempt at a Solution 2x + 2yy' = \frac {x^2 +y^2} {x} then y' = \frac{y} {2x} - \frac{x}{y} let v=y/x ...
  5. S

    Determinant of an orthogonal matrix

    How is it the determinant of an orthogonal matrix is \pm1. Is it: Suppose Q is an orthogonal matrix \Rightarrow 1 = det(I) = det(QTQ) = det(QT)det(Q) = ((det(Q))2 and if so, what is it for -1. Thanks.
  6. I

    How can orthogonal trajectories be found for a specific family of curves?

    The set of orthogonal trajectories for the family indicated by ( x-c)^2 + y^2 = c^2 My work: y' = -(x-c)/y Since c= ( x^2 + y^2 ) / 2x plugging back in and doing -1/y' i got y' = 2xy / ( x^2 - y^2) Then I am supposed to move the x and y to a side and integrate but i don't...
  7. B

    How can ||P|| = 1 be used to show that P = P*?

    Homework Statement Let P be a projection. The definition used is P is a projection if P = PP. Show that ||P|| >=1 with equality if and only if P is orthogonal. Let ||.|| be the 2-normHomework Equations P = PP. P is orthogonal if and only if P =P*The Attempt at a Solution I've proved the...
  8. V

    Solving for Orthogonal Trajectories

    Homework Statement Which of the following is the set of orthogonal trajectories for the family indicated by (x-c)^2 + y^2 = c^2 a). (x-c)^2 + y^2 = c^2 b). (x-c)^2 - y^2 = c^2 c). x^2 + (y-c)^2 = c^2 d). x^2 - (y-c)^2 = c^2 e). None of the above Homework Equations...
  9. H

    Show that it is orthogonal to both u and v

    find u X v and show that it is orthogonal to both u and v. u= 6k v=-i + 3j + k http://s763.photobucket.com/albums/xx275/trinhkieu888/?action=view&current=666.jpg This is what I got from the picture, but my teacher said that I have one more step to do to show that they are orthogonal, I...
  10. B

    Find a ket orthogonal to a given ket

    Homework Statement Given a state \mid \psi \rangle=\frac{1}{\sqrt{3}}[(i+1)\mid 1 \rangle + \mid 2 \rangle], find the normalized state \mid \psi^{'} \rangle orthogonal to to it.Homework Equations \langle \psi^{'} \mid \psi \rangle = 0 \langle \psi^{'} \mid \psi^{'} \rangle = 1The Attempt at...
  11. K

    Orthogonal projectors (minimization and variational problem)

    Homework Statement S1 is in subspace of C^n. P unique orthogonal projector P : C^n -> S1, and x is in range of C^n. Show that the minimization problem: y in range of S1 so that: 2norm(x-y) = min 2norm(x-z) where z in range of S1 and variational problem: y in range of S1 so that...
  12. B

    Proving Orthogonal Projections: Showing 2-Norm Greater Than or Equal to 1

    Homework Statement P is mxm complex matrix, nonzero, and a projector (P^2=P). Show 2-norm ||P|| >= 1 with equality if and only if P is an orthogonal projector (P=P*) Homework Equations Let ||.|| be the 2-norm The Attempt at a Solution a. show ||P|| >= 1 let v be in the range...
  13. E

    Eigenvalue with multiplicity k resulting in k orthogonal eigenvectors?

    I am somewhat confused about this property of an eigenvalue when A is a symmetric matrix, I will state it exactly as it was presented to me. "Properties of the eigenvalue when A is symmetric. If an eigenvalue \lambda has multiplicity k, there will be k (repeated k times), orthogonal...
  14. M

    Proving Orthogonal Compliments of Subspaces in Matrix Algebra

    Homework Statement Let A be an mxn matrix. a. Prove that the set W of row vectors x in R^m such that xA=0 is a subspace of R^m. b. Prove that the subspace W in part a. and the column space of A are orthogonal compliments. Homework Equations The Attempt at a Solution a. to...
  15. E

    Prove that P is an orthogonal projection if and only if P is self adjoint.

    Homework Statement Suppose P ∈ L(V) is such that P2 = P. Prove that P is an orthogonal projection if and only if P is self-adjoint.Homework Equations The Attempt at a Solution Let v be a vector in V. Let w be a vector in W and u be a vector in U and let U and W be subspaces of V where dim W+dim...
  16. J

    How to compute logarithm of orthogonal matrix?

    Suppose X\in\mathbb{R}^{n\times n} is orthogonal. How do you perform the computation of series \log(X) = (X-1) - \frac{1}{2}(X-1)^2 + \frac{1}{3}(X-1)^3 - \cdots Elements of individual terms are ((X-1)^n)_{ij} = (-1)^n\delta_{ij} \;+\; n(-1)^{n-1}X_{ij} \;+\; \sum_{k=2}^{n} (-1)^{n-k}...
  17. T

    Linear Algebra - Find unit vector orthogonal to 2, 4-space vectors?

    Homework Statement Given the vectors u = (2, 0, 1, -4) v = (2, 3, 0, 1) Find any unit vector orthogonal to both of them Homework Equations I know that two vectors are orthogonal if their dot product is zero... The Attempt at a Solution I don't even know how to begin! I know the unit vector...
  18. E

    Proof: P is an Orthogonal Projection with P^2=P

    Homework Statement Let P\inL(V). If P^2=P, and llPvll<=llvll, prove that P is an orthogonal projection.Homework Equations The Attempt at a Solution I think that regarding llPvll<=llvll is redundant. For example, consider P^2=P and let v be a vector in V. Doesn't P^2=P kind of give it away by...
  19. E

    Question about orthogonal projections.

    Aren't all projections orthogonal projections? What I mean is that let's say there is a vector in 3d space and it gets projected to 2d space. So [1 2 3]--->[1 2 0] Within the null space is [0 0 3], which is perpendicular to every vector in the x-y plane, not to mention the inner product of...
  20. L

    What are orthogonal wavefunctions?

    I know what orthogonal means (well, I know orthogonal vectors are perpendicular to each other) but how can this be applied to a wavefunction? Thanks!
  21. B

    Orthogonal complement of a subspace

    Homework Statement Let W be the subspace spanned by the given column vectors. Find a basis for W perp. w1= [2 -1 6 3] w2 = [-1 2 -3 -2] w3 = [2 5 6 1] (these should actually be written as column vectors. Homework Equations The Attempt at a Solution So, I...
  22. X

    Is the Union of W and Its Orthogonal Complement Equal to V?

    Hi, I was just reading about Orthogonal complements. I managed to prove that if V was a vector space, and W was a subspace of V, then it implied that the orthogonal complement of W was also a subspace of V. I then proved that the intersection of W and its orthogonal complement equals 0...
  23. K

    Subgroups of Special Orthogonal Group

    Homework Statement I would like to show that SO3 does not contain any subgroups that are isomorphic to SO2 X SO2. Homework Equations I know that any finite subgroup of SO3 must be isomorphic to a cyclic group, a dihedral group, or the group of rotational symmetries of the tetrahedron...
  24. S

    Non-Zero Orthogonal Vectors: Show m<=n

    I need some direction. Suppose that{u1,u2,...,um} are non-zero pairwise orthogonal vectors (i.e., uj.ui=0 if i doesnt=j) of a subspace W of dimension n. Show that m<=n.
  25. S

    Suppose that{u1,u2, ,um} are non-zero pairwise orthogonal vectors

    I need some direction. I don't have a clue where to start. Suppose that{u1,u2,...,um} are non-zero pairwise orthogonal vectors (i.e., uj.ui=0 if i doesnt=j) of a subspace W of dimension n. Show that m<=n.
  26. L

    Parabolic Coordinates: u,v,φ in x,y,z

    Show that the parabolic coordinates (u,v,\phi) defined by x=uv \cos{\phi} , y=uv \sin{\phi} , z=\frac{1}{2}(u^2-v^2) now I am a bit uneasy here because to do this i first need to find the basis vector right? so if i try and rearrange for u say and then normalise to 1 that will give me...
  27. C

    Finding an Orthogonal Basis of Polynomials Using Gram-Schmidt Process

    Homework Statement Let P2 denote the space of polynomials in k[x] and degree < or = 2. Let f, g exist in P2 such that f(x) = a2x^2 + a1x + a0 g(x) = b2x^2 + b1x + b0 Define <f, g> = a0b0 + a1b1 + a2b2 Let f1, f2, f3, f4 be given as below f1 = x^2 + 3 f2 = 1 - x f3 = 2x^2 + x + 1 f4 = x +...
  28. C

    Finding orthogonal basis for the nullspace of a matrix?

    Homework Statement Find an orthogonal basis for the nullspace of the matrix [2 -2 14] [0 3 -7] [0 0 2] Homework Equations The Attempt at a Solution The nullspace is x = [0, 0, 0], so what is the orthogonal basis? It can be anything can't it?
  29. X

    HELP: orthogonal sets & orthogonal matrices HW problem

    Given a = ( 1, -2, 1), b= ( 0, 1, 2), and c = (-5, -2, 1) determine if {a, b, c} is an orthogonal set. Show support for your answer. I know that if the dot product of every combination equals zero, the set is orthogonal. No problems here. I do that, and they all equal zero. a dot b: 1 * 0 +...
  30. B

    Orthogonal Projection onto XY plane

    I have an assignment question to find an equation of the orthogonal projection onto the XY plane of the curve of intersection of twp particular functions. If some one knows of a good web page that might explain this to me I would be greatly appreciate it. regards Brendan
  31. T

    Orthogonal theoretical question

    V is a space of inner muliplication. W1 and W2 are two subspaces of V, so dimW1<dimW2 prove that there is a vector 0\neq v\epsilon W_2 which is orthogonal to W1 ??
  32. T

    Finding the Complements of W in R^4 to Orthogonal Vectors and Systems

    W is sub space of R^4 which is defined as http://img21.imageshack.us/img21/1849/63042233.th.gif find the system that defines the complements W^\perp of W i have solved the given system and i got one vector (-1,1,0,0) so its complement must be of R^3 and each one of the complements...
  33. R

    Orthogonal group over finite field

    Let O(n,F_q) be the orthogonal group over finite field F_q. The question is how to calculate the order of the group. The answer is given in http://en.wikipedia.org/wiki/Orthogonal_group#Over_finite_fields". This seems to be a standard result, but I could not find a proof for this in the basic...
  34. H

    Constructing orthogonal orbitals from atomic orbitals

    Imagine there is a molecule which consists of several atoms, and for each atom there is an effective orbital, phi_i, which are not orthogonal. Now we want to construct from them a set of orthogonal orbitals, psi_i. Of course there are many ways to do this. Let W be the matrix that realizes our...
  35. J

    Orthogonal basis to two vectors in R4

    Homework Statement Find all vectors that are perpendicular to (1,4,4,1) and (2,9,8,2) The Attempt at a Solution Create matrix A = [[1,4,4,1],[2,9,8,2]] Set Ax = 0 Reduce by Gauss elimination Produces basis of (-4,0,1,0) and (-1,0,0,1) I don't know what the correct solution to...
  36. S

    Operator acting in orthogonal subspace

    Homework Statement Consider a normal operator A If Rperpendiculara1 is the orthogonal complement to the subspace of eigenvectors of A with eigenvalue a1, show that if y exists in all Rperpendiculara1 then Ay exists in all Rperpendiculara1 The Attempt at a Solution This could be answered very...
  37. S

    What is the transitivity of the complex orthogonal group on generalized spheres?

    I'm wondering about the action of the complex (special) orthogonal group on \mathbb{C}^n. In the real case, we can use a (real) orthogonal matrix to rotate any (real) vector into some standard vector, say (a,0,0,...,0), where a>0 is equal to the norm of the vector. In other words, the action...
  38. W

    What is the Orthogonal Property of Vectors in Span?

    Homework Statement If w is orthogonal to u and v, then show that w is also orthogonal to span ( u , v ) Homework Equations two orthogonal vectors have a dot product equalling zero The Attempt at a Solution I can see this geometrically in my mind, and I know that w . u = 0 and w ...
  39. W

    Orthogonal Matrices: Questions & Answers

    Homework Statement 1. If I got a square orthogonal matrix, then if I make up a new matrix from that by rearranging its rows, then will it also be orthogonal? 2. True/false: a square matrix is orthogonal if and only if its determinant is equal to + or - 1 Homework Equations no...
  40. E

    Orthogonal Transformation and condition

    Hi there! In order to proof the orthogonal condition aijaik=\delta_{jk} j,k=1,2,3 I write the invariance of the length of a vector in two coordinate systems: x'ix'i=xixi Using the linear transformation: x'i=ai1xi1+ai2xi2+ai3xi3 the first term becomes: aijaikxjxk My question is: why...
  41. B

    What Is the Difference Between an Orthogonal Complement and Its Basis?

    Homework Statement I don't understand the difference between an orthogonal complement and it's basis. In this problem: W = [x,y,z]: 2x-y+3z=0 Find w's orthogonal complement and the basis for the orthogonal complement. The Attempt at a Solution I did a quick reduced row echelon to [2,-1,3]...
  42. E

    Orthogonal Transformations with Eigenvalue 1

    Homework Statement Prove that an orthogonal transformation T in Rm has 1 as an eigenvalue if the determinant of T equals 1 and m is odd. What can you say if m is even? The attempt at a solution I know that I can write Rm as the direct sum of irreducible invariant subspaces W1, W2, ..., Ws...
  43. D

    2 vectors orthogonal to 3 4-d vectors

    Greetings, I'm a little stuck on this algebra question Find 2 unit vectors orthogonal to v1 = <3,1,1,-1>, v2 = <-1,2,2,0> and v3 = <1,0,2,-1> I know that this means that if I let z be the vector orthogonal to these 3 then, z.v1 = z.v2= z.v3 = 0 And that my two vectors is likely +/-...
  44. D

    Orthogonal Functions | Homework Statement

    Homework Statement http://img55.imageshack.us/img55/8494/67023925dy7.png The Attempt at a Solution All functions orthogonal to 1 result in the fact that: \int_a^b f(t)\ \mbox{d}t =0 Now the extra condition is that f must be continous. (because of the intersection). But...
  45. A

    Inner Product and Orthogonal Complement of Symmetric and Skew-Symmetric Matrices

    Homework Statement Consider the vector space \Renxn over \Re, let S denote the subspace of symmetric matrices, and R denote the subspace of skew-symmetric matrices. For matrices X,Y\in\Renxn define their inner product by <X,Y>=Tr(XTY). Show that, with respect to this inner product, R=S\bot...
  46. L

    Finding a vector orthogonal to others

    I'm sure there's a simple way of doing this but I just can't think of it. In R^n, given k<n linearly independent vectors, how do you find a vector that is orthogonal to all given vectors. I know cross product works for R^3, but what about R^n?
  47. P

    Finding Orthogonal Vectors in R^5 without Cross Product

    Homework Statement Given vectors a=(1,-1,0,2,1) b=(3,1,-2,-1,0) and c=(1,5,2,4,-4), which are mutually orthogonal, find a system of linear equations that a vector x must satisfy so it is orthogonal to a, b, and c.Homework Equations None I think. The Attempt at a Solution This is part A of...
  48. W

    How Is the Rodrigues Rotation Formula Derived in Tensor Notation?

    I'm curious as to how the following proof is verified. I have toiled over this thing for quite a while, but haven't made any progress. I don't need a step-by-step solution, but I would appreciate any help getting it started: Given the following: Q is an orthogonal tensor e1 is a unit...
  49. S

    Find Unit Vector Orthogonal to a & b - Help Needed

    hi! I'm new to the forums, and had a question that was more calculus-related than physics. i saw another post similar to this one, but it was incomplete and i couldn't get the answer with the information on it, any chance someone could help me out? The question is: "Find a unit vector with a...
  50. W

    Do Orthogonal Vectors in 3-D Always Lie on a Straight Line?

    Homework Statement The problem is more of a concept/visual problem, like to find out if it's true or false and why: all vectors orthogonal to a non zero vector in R^3 are contained in a straight line. Homework Equations No equations, just very bad at visualizing in 3-D The...
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