运行了计算轨道的程序，熟悉了一下画图。
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% in search3body.m

function dydt = search3body(t,y)
% search3body Defines the equation of motion of three bodies of equal mass
% Copyright NAOC Qian Lei
% $Revision: 1.0 $  $Date: 2013/08/15 15:43:12 $

x1 = y(1);
y1 = y(2);
x2 = y(3);
y2 = y(4);
x3 = y(5);
y3 = y(6);
x1p = y(7);
y1p = y(8);
x2p = y(9);
y2p = y(10);
x3p = y(11);
y3p = y(12);
fx21 = (x2-x1)./(((x1-x2)^2+(y1-y2)^2)^(3/2));
fx31 = (x3-x1)./(((x1-x3)^2+(y1-y3)^2)^(3/2));
fy21 = (y2-y1)./(((x1-x2)^2+(y1-y2)^2)^(3/2));
fy31 = (y3-y1)./(((x1-x3)^2+(y1-y3)^2)^(3/2));
fx32 = (x3-x2)./(((x2-x3)^2+(y2-y3)^2)^(3/2));
fx12 = (x1-x2)./(((x2-x1)^2+(y2-y1)^2)^(3/2));
fy32 = (y3-y2)./(((x2-x3)^2+(y2-y3)^2)^(3/2));
fy12 = (y1-y2)./(((x2-x1)^2+(y2-y1)^2)^(3/2));
fx13 = (x1-x3)./(((x3-x1)^2+(y3-y1)^2)^(3/2));
fx23 = (x2-x3)./(((x3-x2)^2+(y3-y2)^2)^(3/2));
fy13 = (y1-y3)./(((x3-x1)^2+(y3-y1)^2)^(3/2));
fy23 = (y2-y3)./(((x3-x2)^2+(y3-y2)^2)^(3/2));


dydt = [x1p;...
       y1p;...
       x2p;...
       y2p;...
       x3p;...
       y3p;...
       fx21+fx31;...
       fy21+fy31;...
       fx32+fx12;...
       fy32+fy12;...
       fx13+fx23;...
       fy13+fy23;...
       ];

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% in test search3body.m