WeselyOng

http://imgur.com/R9npR.gif
圓內擺線圖

此為R=3 , r = 1 的圓內擺線圖

以下附上程式碼（參考張智星教授的課本習題）

請自行參透其中奧義

有疑問可以留言

clear all;
% x = 0:0.01:2*pi;
theta = 0:0.01: 2*pi;
r = 1;
r2= 3;
x2 = r2 * cos(theta);
y2 = r2 * sin(theta);
bigcircleH = plot(x2,y2);
plot(x2,y2);
hold on
y = sin(theta);
x = cos(theta);
circle = r*exp(sqrt(-1)*theta);
%  subplot(2,1,1);
circleH=plot(x,y); axis image
set(circleH, 'erase', 'xor');
axis([-4,4,-4,4]);
% axis([-r2-r, r2+r, -0.5, 2*r+0.5]);
dot1H=line(0, 0, 'marker', 'o', 'color', 'k', 'erase', 'xor');
dot2H=line(0, 0, 'marker', '.', 'color', 'r', 'erase', 'none');
% plot(circle);hold on


for i=1:length(theta)
set(circleH, 'xdata', 2*cos(theta(i))+x, 'ydata', 2*sin(theta(i))+y);
angle=-2*theta(i);
    drawnow
set(dot1H, 'xdata', cos(angle)+2*cos(theta(i)), 'ydata', sin(angle)+2*sin(theta(i)));
set(dot2H, 'xdata', cos(angle)+2*cos(theta(i)), 'ydata', sin(angle)+2*sin(theta(i)));
% line('xdata', x(i)+cos(angle), 'ydata', r+sin(angle), 'color', 'r', 'marker', '.');
drawnow
end