# Little triangles appearing in a Mathematica region plot with “opacity” saved in a PDF file [duplicate]

I am trying to produce a region plot of many functions, but Mathematica keeps showing me the little triangles when I save it as pdf. I have seen other solutions which fix the problem with PlotStyle-> color, but the problem here is the opacity of each plot.

An example:

RegionPlot[{Cos[x^2 y] > 0, Sinc[x y + x y^2] <= 0.3}, {x, -1, 1}, {y, -1, 10}]


will produce this plot:

I saw on the internet suggestions such as:

g2 = p2 /. {Polygon[__] -> {}}


Or some functions that include

PlotPoints -> 100


But that does not work when you have two functions superposed over each other. Of course, you might suggest that I use Show then two region plots, but I don't want to deal with the opacity of each plot, and would rather have Mathematica do that for me.

Any suggestions?

Image[RegionPlot[{Cos[x^2 y] > 0, Sinc[x y + x y^2] <= 0.3}, {x, -1, 1}, {y, -1, 10}]]

• @Lina Then there is another method. RegionPlot[{Cos[x^2 y] > 0, Sinc[x y + x y^2] <= 0.3}, {x, -1, 1}, {y, -1, 10}] // FullForm You can see the structure of the Graphics Object. Delete all List with 3 or 4 elements (the triangles and quadrangles), and leave the long List (the curve), then run it. – MMM Apr 20 '14 at 4:05