```Date: May 1, 2013 9:39 PM
Author: David Park
Subject: Re: Intersection points of two contour plots

Do you want something like this:ContourPlot[Sin[3 x y], {x, -3, 3}, {y, -3, 3}, Contours -> {0}, ContourShading -> False, ContourStyle -> Red, RegionFunction -> Function[{x, y}, x y <= 0], Exclusions -> {x == 0, y == 0}] David Parkdjmpark@comcast.net http://home.comcast.net/~djmpark/index.html From: Luiz Melo [mailto:lmelo@ufsj.edu.br] Hi group,Please consider the example below to illustrate my question (the originalproblem 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 twocontour plots?Thank youLuiz
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