function f=peano(n,x1,y1,x2,y2,x3,y3)
if n>1
    trace(1)=(x1+x2)/2;
    trace(2)=(y1+y2)/2;
    trace(3)=(x2+x3)/2;
    trace(4)=(y2+y3)/2;
    trace(5)=(x1+x3)/2;
    trace(6)=(y1+y3)/2;