Re: Exclusions
- To: mathgroup at smc.vnet.net
- Subject: [mg88115] Re: Exclusions
- From: m.r at inbox.ru
- Date: Fri, 25 Apr 2008 05:28:32 -0400 (EDT)
- References: <fuhqv0$rgt$1@smc.vnet.net> <fuin0b$9le$1@smc.vnet.net>
On Apr 22, 5:30 am, Fiona H Evans <fev... at agric.wa.gov.au> wrote:
> On Apr 22, 2:39 am, Jean-Marc Gulliet <jeanmarc.gull... at gmail.com>
> wrote:
>
> Thanks Jean-Marc,
>
> My first post here - I have discovered the limitations of copying and
> pasting. In my notebook, the syntax is correct.
>
> I don't expect an automatic exclusion, but I do get an additional
> (unwanted) exclusion at y==0 && x<0 when I use the following command:
>
> Plot3D[ pdfN[{x, y}], {x, -3, 3}, {y, -3, 3}, PlotRange -> Full,
> Mesh -> 30, ColorFunction -> grayColors, PlotPoints -> 50,
> ClippingStyle -> None,
> Exclusions -> { {ArcTan[x, y] == 0.5,
> x > 0 && y > 0}, {ArcTan[x, y] == -Pi + 0.5, x < 0 && y < 0}},=
> ExclusionsStyle -> {None, Directive[Thick, Red]}, MaxRecursion -> 0,
> AxesLabel -> {"x", "y"}]
>
> Regards, Fiona.
Exclusion search effectively works by bracketing the root, so when you
have ArcTan jump from -Pi to Pi it will also count as a root, similar
to FindRoot[x - Round[x], {x, .25, .75}]. You can try adding a
condition that excludes the unwanted region:
Plot3D[Arg[((x + I y) E^(-.5 I))], {x, -1, 1}, {y, -1, 1},
Exclusions -> {{Arg[x + I y] == -Pi + 0.5,
Abs@ Arg[x + I y] < Pi - .25}},
ExclusionsStyle -> {None, Red},
Method -> {"RotationControl" -> "ArcBall"}]
Maxim Rytin
m.r at inbox.ru