Find the center by taking the average of the x and y coordinates
xCenter = mean(x);
yCenter = mean(y);
then calculate the angles from the center
angles = atand2d((y-yCenter) ./ (x-xCenter));
Then sort
[sortedAngles, sortIndexes] = sort(angles);
x = x(sortedIndexes); % Reorder x and y with the new sort order.
y = y(sortedIndexes);
This is untested, just off the top of my head, so you may have to tweak it a bit. Let me know how it works.
