## How can I animate the drawing of a figure 8 shape in a polar plot to confirm the path it takes?

### Omar Ahmed (view profile)

on 20 Jun 2018
Latest activity Commented on by Omar Ahmed

on 20 Jun 2018

### Steven Yeh (view profile)

Here is my code, where I am taking a figure 8 shape on a polar plot and rotating it around. I want to confirm the path that each figure 8 is drawn by animating it.
start = 0;
end_ = 2*pi;
disc = pi/16;
theta4 = 0:0.01:2*pi;
rho4 = sqrt(4*cos(2*theta4).*(sec(theta4).^4)); % figure 8 function
for i=0:31;
interval = start+i*disc:0.01:end_+i*disc;
%subplot(4,4,i+1)
polarplot(interval,rho4)
hold on
pause(0.2)
end

### Steven Yeh (view profile)

on 20 Jun 2018

Try this:
start = 0;
end_ = 2*pi;
disc = pi/16;
theta4 = 0:0.01:2*pi;
rho4 = sqrt(4*cos(2*theta4).*(sec(theta4).^4)); % figure 8 function
figure()
stepSize = 20;
for i=0:31
interval = start+i*disc:0.01:end_+i*disc;
for k = 1:stepSize:length(rho4)
endPoint = min(k+stepSize, length(rho4)); % avoid array boundary exception
polarplot(interval(k:endPoint), rho4(k:endPoint));
hold on
pause(0.2)
end
end
The stepSize variable used to set the speed of the animation
You can set the color in the outer i loop

Omar Ahmed

on 20 Jun 2018
Thank you