Re: Re: v.6 RevolutionPlot3D

• To: mathgroup at smc.vnet.net
• Subject: [mg75947] Re: [mg75895] Re: [mg75852] v.6 RevolutionPlot3D
• From: Murray Eisenberg <murray at math.umass.edu>
• Date: Mon, 14 May 2007 03:28:37 -0400 (EDT)
• Organization: Mathematics & Statistics, Univ. of Mass./Amherst
• References: <26790717.1178958081186.JavaMail.root@m35> <200705130938.FAA02288@smc.vnet.net>
• Reply-to: Murray Eisenberg <murray at math.umass.edu>

I see that example differently:  Given that the axes labels are in the
usual order x, y, z, all that's happening in the pre-computed output
cell is that the 3D image has been dragged with the mouse so as to
orient the z-axis toward the right (instead of up).

And one can do the same thing after evaluating the input cell and fake
the result by relabeling the axes so as to make it LOOK like the axis of
revolution is the x-axis of the y-axis.

The ViewVertical option, mentioned in a separate posting on this
subject, of course accomplishes the same thing.

Still, it does seem a shame not to have a direct option as to what the
axis of rotation is, as in the RevolutionAxis option for the pre-6.0
Graphics`SurfaceOfRevolution.

DrMajorBob wrote:
> There's an example in help for RevolutionPlot3D (under Possible Issues):
>
> RevolutionPlot3D[{t, t^2}, {t, 0, 2}, AxesLabel -> {x, y, z},
>   Ticks -> None]
>
> that, when evaluated, IS revolved about the z axis, but the output cell
> BEFORE I calculate the cell (by pressing enter) is NOT revolved about the
> vertical axis. How did that happen?
>
> Oh!!! I see the same thing in other examples... in help for
> RotationAction, for instance.
>
> Bobby
>
> On Sat, 12 May 2007 02:00:04 -0500, Helen Read <read at math.uvm.edu> wrote:
>
>> We just got 6.0 on our site license, and I installed on my computer(s)
>> yesterday.
>>
>> I see that SurfaceOfRevolution (which was in an add on package) has been
>> replaced by RevolutionPlot3D. Sounds great, except that RevolutionPlot3D
>> only revolves around the vertical axis. We (my calculus students) used
>> the old SurfaceOfRevolution all the time for visualizing surfaces of
>> revolution for computing volume and surface area, and we need to be able
>> to revolve around both the vertical axis and the horizontal axis. This
>> was a simple matter of setting RevolutionAxis->{0,0,1} or
>> RevolutionAxis->{1,0,0} respectively. Now, I can write a function for
>> revolving around the horizontal axis and provide it to the students, but
>> I can already foresee the confusion it will cause when they can use a
>> built-in function for revolving in one direction, and have to do it a
>> different way to revolve in the other direction.
>>
>> --
>> University of Vermont
>>
>>
>
>
>

--
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305

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