% chase.m
%
global a b m c w    % transmit path and speed information to fkt
a = 30; b = 30;     % semi-axes of ellipse
m = [0;0];          % center
c = 17.58940018;    % constant speed of target
w = 18.5;           % speed of robot
%
% set graphics window to accept input
%
axis equal;
axis ([-40 40 -40 40]);
[Initial_Data(1), Initial_Data(2)] = ginput (1);    % mouse is used to identify intial robot position 
Initial_Data(3) = 0;    %initial time
%
% set up parameters for differential equation
%
timelimit = 20;     % final time
framerate = 16;     % in frames per second for movie
tspan = linspace (0, timelimit, timelimit*framerate+1);
options= odeset('AbsTol',1e-5,'Events','on');
[t,robot]= ode45 ('fkt', tspan, Initial_Data, options);
nframes = length(t);      % number of output points
target = zeros(p, 2);   % initialize array for target
% 
% compue target position
%
target(:, 1)= m(1)+a*cos(robot(:,3));
target(:, 2)= m(2)+b*sin(robot(:,3));