"Animated" graph during cycle

Hi everybody, I've got a problem I'm trying to plot a particular orbit of a satellite during a while cycle, but Matlab collects all the data and plot them at the end of the cycle. I don't know if the mistake I made is in the structure of the cycle or in the formulas, but it takes an infinity of time and at the end it shows, in the graph, an infinity of wrong lines :P

The code I'm using is this one, there is already the graph of the Earth existing

    while Rmbt ~= Rmtar
    Rtar = [Rmtar * cos(theta2) Rmtar * sin(theta2)];
    Rmbt = at * (1 - ebt^2) / (1 + ebt * cos(theta1));
    Rbt = [Rmbt * cos(theta1) Rmbt * sin(theta1)];
    theta1 = theta1 + 1;
    theta2 = theta2 + 1;
    plot (Rtar(1), Rtar(2), 'r')
    hold 
    plot (Rbt(1), Rbt(2), 'b')
    hold all
end

where Rmbt is the "moving" trajectory and Rmtar is the target trajectory, they are the radius bi-dimensional vectors of the satellites, while "theta1/2" are the angles

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I'd like to see the orbit that evolves in time reaching the second one.

Thank you all

Answer 1

[Walter Roberson]

http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F