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Homework Help: Linear Algebra Homework help

  1. Sep 30, 2012 #1
    Linear Algebra Homework help!!

    1. The problem statement, all variables and given/known data
    Suppose a particular object is modelled as moving in an elliptical orbit centered at
    the origin. Its nominal trajectory is described in rectangular coordinates (r;s) by the
    constraint equation x1r^2 +x2s^2 +x3rs = 1, where x1; x2; and x3 are unknown parameters that specify the orbit. We have available the following noisy measurements of
    the object’s coordinates (r;s) at ten different points on its orbit:

    (0:6925;0:0592) (0:3582;0:4110) (0:2514;0:3763) (0:0764;0:5453)
    (0:4249;0:3768) (0:6917;0:0252) (0:3831;0:2116) (0:0027;0:3801)
    (0:0865;0:3628) (0:5428;0:2889)
    Using the assumed constraint equation, arrange the given information in the form of
    the linear system of equation Ax + b, where A is a known 10x3 matrix, b is a known
    10 x1 vector, and x = (x1; x2; x3)^T.
    This system of 10 equations in 3 unknowns is inconsistent. We wish to find the solution x that minimizes the Euclidean norm of error Ax +b. Compare the solution obtained by using the following MATLAB invocations, each of which in principle gives the desired least-square-error solution:
    (a). x = A\b
    (b). x = pinv(A) *b
    (c). x = inv(A'*A)*A'*b

    Plot the ellipse that corresponds to your estimate of x. Attach the m-fil

    I am way over my head guys! please help a girl out!
  2. jcsd
  3. Sep 30, 2012 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    Re: Linear Algebra Homework help!!

    Welcome to PF;
    It helps to give it a shot and tell us about it.
    You should have some examples of this sort of thing in your notes and your coursework to date so you do have someplace to start from. Show your reasoning until you get stuck and we'll be able to help where you get unstuck.

    BTW: there are lots of ways to fit conics to noisy data ... when you work through from your notes, we'll be tipped off about which one you are supposed to be using.
    So far it looks like a regularization problem.
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