f0(x,y0,y1)=y0+y1
f1(x,y0,y1)=y0-y1
MMiddlePoint([f0(x,y0,y1);f1(x,y0,y1)],[1,0],0.5,1.5,20)
m=MMiddlePoint([f0(x,y0,y1);f1(x,y0,y1)],[1,0],0.5,1.5,20)
m