RE: non integer exponents in ContourPlot[]?
- To: mathgroup at smc.vnet.net
- Subject: [mg35226] RE: [mg35209] non integer exponents in ContourPlot[]?
- From: "Wolf, Hartmut" <Hartmut.Wolf at t-systems.com>
- Date: Wed, 3 Jul 2002 05:13:26 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
> -----Original Message----- > From: 1.156 [mailto:rob at piovere.com] To: mathgroup at smc.vnet.net > Sent: Tuesday, July 02, 2002 8:12 AM > To: mathgroup at smc.vnet.net > Subject: [mg35226] [mg35209] non integer exponents in ContourPlot[]? > > > Mathematica wizards all: > > The following code runs fine, note the (apparent) floating > point form of the exponents. > > a=-5.75;b=2;d=1.1; > > ContourPlot[a*((x^2.0 + y^2.0)^0.5 + b*y^2.0), {x, -d, d}, > {y, -d, d}, ContourShading -> False, > Contours -> {-6, -3, -1}, PlotPoints -> 30]; > > But, if I make any of the 2.0 exponents say, 2.1, I get big > error messages like > > ContourGraphics::ctpnt: > The contour is attempting to traverse a cell in which some > of the points have not evaluated to numbers, > and it will be dropped. > > However, it works fine if I change the 0.5 exponent to say, 0.55. > > Can anyone give me a hint of what's going on here? I'd sure > like to be able to play with these exponents to fit some data. > > Thanks, Rob > > Rob, perhaps you might like to try expon = 3.; (* or 2.1, or ... *) ContourPlot[ a*(Abs[x^expon + y^expon]^0.5 + b*Abs[y]^expon), {x, -d, d}, {y, -d, d}, ContourShading -> False, Contours -> {-6, -3, -1}, PlotPoints -> 100]; -- Hartmut