马鞍面(双曲抛物面)(Saddle)
说明:这种曲面之所以称为“马鞍面”,是因为它在原点附近的图形很像一副马鞍。
曲面的Maple程序(用显函数绘制):
with(plots): a:=2:
qumian:=plot3d(x*y,x=-a..a,y=-sqrt(a^2-x^2)..sqrt(a^2-x^2)):
x_axis:=plot3d([u,0,0],u=-1..1,v=0..0.01,color=blue):
y_axis:=plot3d([0,u,0],u=-1..1,v=0..0.01,color=blue):
z_axis:=plot3d([0,0,u],u=-1..1,v=0..0.01,color=blue):
xyz:=display(x_axis,y_axis,z_axis,thickness=3):
display(qumian,xyz,tickmarks=[4,4,4], axes=none, grid=[40,40],lightmodel=light2);
with(plots):
a:=1:b:=1:
qumian:=plot3d([a*lamda/2+a*t,b*lamda/2-b*t,2*lamda*t],t=-3..3,lamda=-3..3,scaling=unconstrained,lightmodel=light3,view=[-3..3,-3..3,-10..10],grid=[30,30]):
x_axis:=plot3d([u,0,0],u=-4..4,v=0..0.01,thickness=3):
y_axis:=plot3d([0,u,0],u=-4..4,v=0..0.01,thickness=3):
z_axis:=plot3d([0,0,u],u=-6..6,v=0..0.01,thickness=3):
xyz:=display(x_axis,y_axis,z_axis,thickness=3):
display(qumian,xyz,tickmarks=[4,4,4],axes=none);
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