Re: non integer exponents in ContourPlot[]?

*To*: mathgroup at smc.vnet.net*Subject*: [mg35247] Re: [mg35209] non integer exponents in ContourPlot[]?*From*: Tomas Garza <tgarza01 at prodigy.net.mx>*Date*: Wed, 3 Jul 2002 05:16:06 -0400 (EDT)*References*: <200207020612.CAA22327@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Ok, just beware of complex numbers. It is very hard to get them into a plot. You see, for example, In[1]:= x^2 .0/. x -> -1.1 Out[1]= 1.21 a real number. However, In[2]:= x^2.1 /. x -> -1.1 Out[2]= 1.161798 + 0.377491*I a complex number. The function you obtain when you change the exponents from 2.0 to 2.1 is impossible to plot. (Incidentally, in Mathematica a number such as 2.0 or 2.1 is not called "floating point", but just "real"). Tomas Garza Mexico City ----- Original Message ----- From: "1.156" <rob at piovere.com> To: mathgroup at smc.vnet.net Subject: [mg35247] [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 > >

**References**:**non integer exponents in ContourPlot[]?***From:*"1.156" <rob@piovere.com>