> N[3]:=(xi,eta) -> (1+xi)*(1+eta)*(9*(xi^2+eta^2)-10)/32;

                                                    2        2
  N[3] := (xi, eta) -> 1/32 (1 + xi) (1 + eta) (9 xi  + 9 eta  - 10)

> plot3d(N[3],-1..1,-1..1,grid=[15,15],axes=boxed,scaling=constrained,
> style=patch,orientation=[-60,60]);

> 
> 
