fplot3d1 - 3D gray or color level plot of a surface defined by a function
fplot3d1 plots a 3D gray or color level plot of a surface defined by the external function f on the grid defined by xr and yr.
Enter the command fplot3d1() to see a demo.
deff('z=f(x,y)','z=x^4-y^4') x=-3:0.2:3 ;y=x ; xbasc() ;fplot3d1(x,y,f,alpha=5,theta=31)