1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Linear algebra/matlab: find vector when e2 is reflected over line B with x-axis

  1. Mar 9, 2010 #1
    1. The problem statement, all variables and given/known data
    The assignment is to find a matrix, A, that multiplied by a matrix that represents a rectangle will reflect that rectangle about a line through the origin that is at and beta with the x axis. This is all in homogenous coordinates.

    2. Relevant equations
    Elementary vectors: e1 is <1,0, ... 0> e2 is <0,1,0 ...> etc.
    No others.

    3. The attempt at a solution
    I thought that the matrix might be: (I hope this formats correctly)
    cos(2B) sin(2B) 0
    sin(2B) -cos(2B) 0
    0 0 1
    But when I use this in Matlab, it seems to rotate the rectangle represented by my first matrix in 3 dimensions, rather than reflect it in two dimensions. So right now I am left trying to remake the matrix.

    I am trying to figure out the transformation applied to the elementary vectors. When the elementary vector e1 is reflected, that gives me the transformation vector <cos2B,sin2B>
    but I am having a lot of trouble figuring out the same vector when e2 is reflected. Any ideas? Thank you.
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted