h0=figure('toolbar','none',...
    'position',[198 56 350 468],...
    'name','實例58');
h1=axes('parent',h0,...
    'position',[0.25 0.45 0.5 0.5],...
    'visible','off');
t=0:0.1:4*pi;
x=sin(t);
y=cos(t);
plot(x,y)
axis equal
axis off
h=line('color',[1 0 0],...
    'linestyle','.',...
    'xdata',0,...
    'ydata',1,...
    'markersize',20,...
    'erasemode','xor');
n=length(t);
i=1;
speed=0.01;
k=0;
b1huidiao=[...
        'k=0;,',...
        'while 1,',...
        'set(h,''xdata'',x(i),''ydata'',y(i));,',...
        'drawnow,',...
        'pause(speed),',...
        'i=i+1;,',...
        'if i>n,',...
        'i=1;,',...
        'end,',...
        'if k==1,',...
        'break,',...
        'end,',...
        'end'];
b1=uicontrol('parent',h0,...
    'units','points',...
    'tag','b1',...
    'style','pushbutton',...
    'string','開始',...
    'backgroundcolor',[0.75 0.75 0.75],...
    'position',[30 80 50 20],...
    'callback',b1huidiao);
b2=uicontrol('parent',h0,...
    'units','points',...
    'tag','b2',...
    'style','pushbutton',...
    'string','停止',...
    'backgroundcolor',[0.75 0.75 0.75],...
    'position',[100 80 50 20],...
    'callback','k=1;');
b3=uicontrol('parent',h0,...
    'units','points',...
    'tag','b3',...
    'style','pushbutton',...
    'string','關閉',...
    'backgroundcolor',[0.75 0.75 0.75],...
    'position',[170 80 50 20],...
    'callback',[...
        'k=1;,',...
        'close']);
s1=uicontrol('parent',h0,...
    'units','points',...
    'tag','s1',...
    'style','slider',...
    'value',50*speed,...
    'max',1,...
    'min',0,...
    'backgroundcolor',[0.75 0.75 0.75],...
    'position',[30 115 190 20],...
    'callback',[...
        'm=get(s1,''value'');,',...
        'speed=m/50;']);
t1=uicontrol('parent',h0,...
    'units','points',...
    'tag','t1',...
    'style','text',...
    'fontsize',15,...
    'string','小球運動速度',...
    'backgroundcolor',[0.75 0.75 0.75],...
    'position',[30 135 190 20]);