polyshape is pretty good for this, but you need to give it polygons not curves (i.e. define what's inside and what's outside). Nice bonus is that you get a shape, so you can both plot it and get stats like area:
t=linspace(0,2*pi,100)';
t=t(1:end-1);
x=3*cos(t)-2;
y=3*sin(t)-2;
p1 = polyshape([x y]);
p2 = nsidedpoly(100,'Radius',4,'Center',[1 1]); % shortcut for regular polygons
p3 = nsidedpoly(4);
hold on
p1.plot('FaceColor',[.6 .4 .4]) % plot as polyshapeobject.plot...
p2.plot('FaceColor',[.4 .6 .4])
p3.plot('FaceColor',[.4 .4 .6])
intersected_p = p1.intersect(p2).intersect(p3);
plot(intersected_p,'FaceColor','r','LineWidth',2) % ...or plot(polyshape)
intersected_p.area
