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Homework Help: Magnetic Pendulum Fractal Basin Boundaries in Mathematica

  1. Feb 3, 2013 #1
    1. The problem statement, all variables and given/known data

    Hey all, this is for a laboratory. I need to determine the fractal basin boundaries for a magnetic pendulum swinging chaotically about 3 other magnets underneath. I was able to plot a single path for the pendulum in Mathematica, but now I need to expand my code to determine each endpoint for each starting point. I'm thinking that a Do loop involving lists might work, but for the life of me I can't figure out how to incorporate the functions NDSolve, List and Do. I COULD do each path individually and record the results, but I really don't think that's practical.

    2. Relevant equations
    y''[t] + r y'[t] - Ʃ(Yi-y[t])/√((Xi-x[t])^2 + (Yi-y[t])^2 + d^2)^3 + c y[t] ==0

    The sum is for Y1, Y2 and Y3 (and X1, X2 and X3) which are the coordinates of the magnets. The other equation for the displacement of x[t] is the same as for y[t], so I don't see the need to write it twice.

    r,c,d are all constants, where r is air resistance, d is the distance between the pendulum and the sitting magnets if it were directly over it. c is the spring constant of the pendulum.

    I've attached a couple notebooks so that you can see more clearly what I'm doing.

    3. The attempt at a solution
    My attempt at the solution is to make a Do loop in which Mathematica uses NDSolve for each starting coordinate from {-5,-5} to {5,5} in increments of 0.1 and outputs the endpoint at around 100 seconds when the pendulum is basically circling a single magnet. I understand what I have to find out, but for the life of me I can't figure out how to make it work!

    Attached Files:

  2. jcsd
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