设置选项让曲面透明和无边界框去观察马鞍面(抛物面)
A.
Plot3D[x^2-y^2,{x,-3,3},{y,-3,3},PlotStyle→Opacity[0.2], Boxed→False]
B.
Plot3D[x^2-y^2,{x,-3,3},{y,-3,3},Boxed→False,PlotStyle→Opacity[0.3]]
C.
Plot3D[x^2-y^2,{x,-3,3},{y,-3,3},PlotStyle→Opacity[1.0],BoxRatios→{1,1,1}]
D.
Plot3D[x^2-y^2,{x,-3,3},{y,-3,3},BoxRatios→{1,1,1},PlotStyle→Opacity[0.25]]