       Re: How to draw several contours for one function, while

• To: mathgroup at smc.vnet.net
• Subject: [mg127680] Re: How to draw several contours for one function, while
• From: Bob Hanlon <hanlonr357 at gmail.com>
• Date: Wed, 15 Aug 2012 03:30:45 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• Delivered-to: l-mathgroup@wolfram.com
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• References: <20120814082402.2D8BD6862@smc.vnet.net>

```Without knowing the functions it is difficult to guess the best way to
show what you might want to see. Manipulate may be a better way than
Animate to examine what is going on.

Manipulate[
pts = {x, y} /.
Solve[{
f[x, y, a] == intersect,
g[x, y, a] == 0},
{x, y}, Reals];
Show[
ContourPlot[f[x, y, a],
{x, -8, 8}, {y, -8, 8},
Contours -> Range[0, 75, 15],
ContourStyle -> Hue /@ (.7 Range[0, 1, 15/75] + .15),
ContourLabels -> All],
ContourPlot[g[x, y, a] == 0,
{x, -8, 8}, {y, -8, 8},
ContourLabels -> All],
Graphics[{Red, AbsolutePointSize,
Tooltip[Point[#], #] & /@ pts}],
PlotRange -> {{-8, 8}, {-7, 8}}],
{{a, 0}, -5, 5, .5, Appearance -> "Labeled"},
{{intersect, 0}, 0, 75, 5, Appearance -> "Labeled"},
Initialization :> {
f[x_, y_, a_] = (x - a/2)^2 + (y - a/4)^2 - 2,
g[x_, y_, a_] = x + y - a}]

Bob Hanlon

On Tue, Aug 14, 2012 at 4:24 AM,  <loveinla at gmail.com> wrote:
> Dear all,
>
> Suppose I have two implicit functions, say, F(x, y) and G(x, y); both involve a parameter a.
>
> In one Animate, I need:
>  (1) several contours for function F(x, y) with its Max and Min values;
>  (2) only one contour for function G(x, y)==0.
>  (3) because I need to see how they change as parameter a changes, I want to use Animate to generate animation.
>
> Can anybody help? Thanks.
>

```

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