Re: non integer exponents in ContourPlot[]?

*To*: mathgroup at smc.vnet.net*Subject*: [mg35228] Re: non integer exponents in ContourPlot[]?*From*: "Allan Hayes" <hay at haystack.demon.co.uk>*Date*: Wed, 3 Jul 2002 05:13:31 -0400 (EDT)*References*: <afrgq3$lt1$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Rob, The function is not evaluating to a *real* number at some pointgs (this should have been made explicit in the message) There are several ways out, one is to change the function to Re[...]. Allan --------------------- Allan Hayes Mathematica Training and Consulting Leicester UK www.haystack.demon.co.uk hay at haystack.demon.co.uk Voice: +44 (0)116 271 4198 Fax: +44 (0)870 164 0565 "1.156" <rob at piovere.com> wrote in message news:afrgq3$lt1$1 at smc.vnet.net... > 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 > >