> "analytic cylinder" you mean - cylinder created from draw solid menu?

Yeah, or also extrusion of a circle will generate one also - if you turn on the control points of the sweep-constructed cylinder you'll see it has 4 control points in the straight direction instead of it only being 2 points in the straight direction. Basically sweeps are focused on making curvy shapes and go through a refinement/fitting process as part of the construction, one byproduct of that is that the surface will always be a cubic in that direction.

Extrusion or draw solid > cylinder make a more basic cylinder that also will be a special class of surface that can generate more precise results for some kinds of intersections.

- Michael

Thanx for clear Explanation.
This is the screen of control points first extruded, and second by sweep.
I can not see 4 points in stright direction on sweeped cylinder, may be I did something wrong?

Hi mir4ea,

> I can not see 4 points in stright direction on sweeped cylinder, may be I did something wrong?

You're only seeing the control points on the curves there (the line and the circle you used as inputs to make the sweep), not any surfaces. In order to turn on control points of surfaces that are joined at trimmed edges you need to use Edit > Separate to break them into separate pieces and then you can turn on points. See here for more info on that:
http://moi3d.com/wiki/FAQ#Q:_Why_does_show_points_work_for_some_objects_but_not_others.3F

- Michael

Got it thanx.