z 1 = x ./(y+ 1)；

z2 = x . * y ./(y+ 1)；

Figure (1)

surf(x，y，z 1)

Figure (2)

Surface (x, y, z2)

The third one doesn't know! Subtract v0

Suppose v0 = 2;

[x，y]= mesh grid(- 10: 10)；

z 1=(2+x)。 /(y+ 1)；

z2 = x . * y ./(y+ 1)；

z=min(z 1，z2)；

Surfing (x, y, z)

Do you think so?