Proceed something like this:
xc=50; %xCenter
yc=50; %yCenter
a=25; %xRad
b=100; %yRad
m = 1000;
theta = linspace(0,2*pi,m)';
x = a * cos(theta);
y = b * sin(theta);
alpha = linspace(0,2*pi) ;
figure(1)
filename = 'test.gif';
for i = 1:100
R = [cos(alpha(i)) -sin(alpha(i)); ...
sin(alpha(i)) cos(alpha(i))];
rCoords = R*[x' ; y'];
xr = rCoords(1,:)';
yr = rCoords(2,:)';
plot(xc+xr,yc+yr,'b');
drawnow
frame = getframe(1);
im = frame2im(frame);
[imind,cm] = rgb2ind(im,256);
if i == 1
imwrite(imind,cm,filename,'gif', 'Loopcount',inf);
else
imwrite(imind,cm,filename,'gif','WriteMode','append');
end
end
