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