theta=3＊pi／2：-0.04：pi／2

　　clear all

close all

clc

% straight line 1 of the athletic track

x1=-10:0.2:10;

y1=0*x1+5;

% semi-circle 1 of the athletic track

theta=pi/2:-0.04:-pi/2;

x2=5*cos(theta)+10;

y2=5*sin(theta);

% straight line 2 of the athletic track

x3=10:-0.2:-10;

y3=0*x3-5;

% semi-circle 2 of the athletic track

theta=3*pi/2:-0.04:pi/2;

x4=5*cos(theta)-10;

y4=5*sin(theta);

% Include straight lines and semi-circles to get an entire athletic track

x=[x1 x2 x3 x4];

y=[y1 y2 y3 y4];

% Two cycles of the athletic track

x=[x x];

y=[y y];

% plot the athletic track

plot(x,y)

axis([-16,16,-6,6])

axis equal

hold on

for i=1:length(x)

k1=fix(1.1*i); % define velocity of the 1st player (uniform velocity)

if k1>length(x)

k1=length(x);

end

h1=plot(x(k1),y(k1),'Color',[1 0 0],'Marker','o','LineWidth',5); % show location of the 1st player

k2=fix(1+5*i^(0.76)); % define velocity of the 2nd player (faster at the beginning, then slower)

if k2>length(x)

k2=length(x);

end

h2=plot(x(k2),y(k2),'Color',[k2/length(x) 0 k2/length(x)],'Marker','s','LineWidth',5); % show location of the 2nd player