Re: ContourPlot confusion
- To: mathgroup at smc.vnet.net
- Subject: [mg116384] Re: ContourPlot confusion
- From: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>
- Date: Sat, 12 Feb 2011 05:21:28 -0500 (EST)
- References: <ij2ukh$7im$1@smc.vnet.net>
I suppose it should evaluate to 0. If it's a wildly changing function
you may expect large values in the neighbourhood of this line. If you
would disclose your function there might be more to say here.
Cheers -- Sjoerd
On Feb 11, 10:13 am, kelly <kere... at gmail.com> wrote:
> Hi! I'm plotting the following:
>
> ContourPlot[Expression[50, x, y] == 0), {x, -15, -17}, {y, -0.7, -0.5}]
>
> So some previously defined expression which is a function of 50, x, and y. I've set it to only show the "Expression = 0" contour, which it does.
>
> However, when I use "Get Coordinates" to get the coordinates of a point along this contour line & plug those coordinates back into the expression, it evaluates to around -33. Shouldn't it evaluate to 0 if the point lies along the 0 contour?
>
> Any help is appreciated! So confused!