Re: Intersection points of two contour plots

• To: mathgroup at smc.vnet.net
• Subject: [mg130685] Re: Intersection points of two contour plots
• From: Bob Hanlon <hanlonr357 at gmail.com>
• Date: Wed, 1 May 2013 21:42:31 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• Delivered-to: l-mathgroup@wolfram.com
• Delivered-to: mathgroup-outx@smc.vnet.net
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• References: <20130501073614.4E7136A05@smc.vnet.net>

```ContourPlot[Sin[3 x*y] == 0,
{x, -3, 3}, {y, -3, 3},
RegionFunction ->
Function[{x, y}, x*y < 0],
Exclusions -> {x*y == 0},
ContourStyle -> Black]

or

t1 = Table[
If[x*y < 0, Sin[3 x*y], Sequence[]],
{x, -3, 3, .1}, {y, -3, 3, .1}];

ListContourPlot[t1,
Contours -> {0},
DataRange -> {{-3, 3}, {-3, 3}},
RegionFunction ->
Function[{x, y}, x*y < 0],
ContourStyle -> Black]

Bob Hanlon

On Wed, May 1, 2013 at 3:36 AM, Luiz Melo <lmelo at ufsj.edu.br> wrote:

> Hi group,
> Please consider the example below to illustrate my question (the
> original problem is somehow much more complicated):
>
> t1 = Table[Sin[3 x*y], {x, -3, 3, .1}, {y, -3, 3, .1}];
>
> t2 = Table[If[x*y < 0, Sin[3 x*y]], {x, -3, 3, .1}, {y, -3, 3, .1}];
>
> p1 = ListContourPlot[t1, Contours -> {0}, ContourShading -> False,
>    DataRange -> {{-3, 3}, {-3, 3}}, ContourStyle -> Black];
>
> p2 = ListContourPlot[t2, Contours -> {0}, ContourShading -> False,
>    DataRange -> {{-3, 3}, {-3, 3}}, ContourStyle -> {Red, Dashed, Thick}];
>
> Show[p1, p2]
>
> Is there a way to show only the results of the intersection of these
> two contour plots?
>
> Thank you
> Luiz
>
>

```

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