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Re: Re: Problem with RegionFunction

  • To: mathgroup at smc.vnet.net
  • Subject: [mg88126] Re: [mg88084] Re: Problem with RegionFunction
  • From: "W_Craig Carter" <ccarter at mit.edu>
  • Date: Fri, 25 Apr 2008 05:30:30 -0400 (EDT)
  • References: <fukern$s4l$1@smc.vnet.net> <fumqti$sc8$1@smc.vnet.net>

Hello Zac,
This was explained to me the following way. WIthin Manipulate, the
PerformanceGoal option switches from
Speed to Quality when a manipulate variable stops changing. Thus, the
change in appearance of Graphics3D objects while sliding.  To handle
the boundaries of a plot well, values are probed on either side of the
boundary even though they are not going to appear on the final plot.
PerformanceGoal as I understand it, changes the way that plot resolves
the boundaries and thus your 0^0.

I hope this explanation is not too far off the mark.

WCC

On Thu, Apr 24, 2008 at 5:56 AM, zac <replicatorzed at gmail.com> wrote:
> Thank you for the answers.
>
>  I understand that the case where x=0 and y=0 is undefined, but I don't
>  understand why does Mathematica compute this case when ranges are
>  given explicitely to avoid such situations? Why do I have to define
>  the regionfunction to exclude x=0 and y=0 (as Fred suggested it)? Is
>  it not trivial to exclude these as the PlotRange dictates it? Why is
>  it that the problem does not surface when I omit the Manipulate[...]
>  wrap?
>  Istvan
>
>
>
>  On Apr 23, 10:10 am, Jens-Peer Kuska <ku... at informatik.uni-leipzig.de>
>  wrote:
>  > Hi,
>  >
>  > try
>  >
>  > Manipulate[
>  >   Plot3D[Sin[x]*Cos[y], {x, 1, 10}, {y, 2, 10},
>  >    RegionFunction -> Function[{x, y}, 45 <= (y^x)],
>  >    Exclusions -> x == 0], {dummy, {True, False}}]
>  >
>  > because y^x for x==0 and y==0 is undefined.
>  >
>  > Regards
>  >    Jens
>
>



-- 
W. Craig Carter


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