With[{r = Sqrt[x^2 + y^2], th = ArcTan[x, y]},
ContourPlot[
  r/2 (1 - 1/r^2) + r/2 Cos[2*th] (1 - 1/r^2) (1 - 3/r^2), {x, 0,
   2}, {y, 0, 2}]
]

2楼: Originally posted by chyanog at 2013-11-14 12:39:55
With[{r = Sqrt, th = ArcTan},
ContourPlot
]

3楼: Originally posted by onexf766 at 2013-11-16 21:09:19
谢谢你，你的和我没有差别
可能是我没有表达清楚。我的意思是：要做一个图，它的取值范围在 1<r<2，也就是在0<r<1范围为空白（这样就不会出来那些难看的黑线了）。不要说另外用一个函数的图来 ...

6楼: Originally posted by walk1997 at 2013-12-17 22:43:12
ContourPlot...