If you go to an infinite cylinder it has a vessel function. And if you go to an infiniteslab it has a cosine type shape.
如果是一个无限的圆柱，它有，管道功能，如果是一个无限的平板，它有余弦的形状。
2
You can see the normalized flux versus the normalized distance and that the shapes are basically cosine regardless of whether it's an infiniteslab or an infinite cylinder.