In[92]:=
ParametricPlot3D[{u^2,u v,v},{u,0,2},{v,0,2}];

In[93]:=
Show[%, ViewPoint->{0,1,0}];

I hope you can see that this is equivalent to z=y/Sqrt[x].
In[94]:=
Plot3D[y/Sqrt[x],{x,.1,4},{y,0,4}];

In[95]:=
Show[%, ViewPoint->{0,1,0}];

Up to z=S(x, y) or R=R(u, v) ?