Re: ContourPlot doesn't work properly?
- To: mathgroup at smc.vnet.net
- Subject: [mg23852] Re: ContourPlot doesn't work properly?
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Mon, 12 Jun 2000 01:17:43 -0400 (EDT)
- References: <8hsucc$dhq@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
I get the message
ContourGraphics::ctpnt:
The contour is attempting to traverse a cell in which some of the
points have not evaluated to numbers, and it will be dropped.
and an empty frame for both of your examples.Which is understandable because
Log[y] is complex when x<0 and not defined when x=0.
However
ContourPlot[Log[y]-x,{x,-10,10},{y,0.001,10},
PlotPoints->30,Contours->{0},ContourShading->False]
works shows a curve.
Allan
---------------------
Allan Hayes
Mathematica Training and Consulting
Leicester UK
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565
"Higinio Ramos Calle" <higra at gugu.usal.es> wrote in message
news:8hsucc$dhq at smc.vnet.net...
>
> Let's take a common function like y=Exp[x]
> If I try to make a picture of this function in an implicit way with
> ContourPlot in the form
> ContourPlot[Log[y]-x,{x,-10,10},{y,-10,10},
> PlotPoints->30,Contours->{0},ContourShading->False]
>
> with the option PlotPoints->30 in order to have a more precise picture I
> obtain an error message:
>
> 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.
>
> and no picture.
>
> But if I let the option PlotPoints his default value the message is the
> same, but now the picture is drawn.
>
> Could anyone explain what happens?
>
> higra at gugu.usal.es
>