I need to find chain code for the plotted image

Hi sir, I have x, y coordinates and plotted image using plot().Now I need to find chain code for the plotted image since I am new to matlab pls help me and the x, y points are x=[1 2 3 4 5 6 7 8 9 10 10 11 12 12 13 13 14 15 15 15 14 14 13 12 12 13 14 15 16 17 18 19 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 5 6 6 7 7 7 6 5 4 3 2 1 1 1.1];

y=[10 10 11 12 12 13 14 15 16 17 18 19 20 21 22 23 23 23 22 21 20 19 18 17 16 16 16 17 17 18 18 17 16 15 14 13 13 12 11 10 9 8 7 6 5 4 4 5 6 7 8 9 10 11 10 9 9 8 8 9 10 10 ];