The method of contourf fill

[Jan Tosovsky]

Dear All,

when exporting the following example into a vector graphic (PDF or PS), the
final fill consist of narrow triangles, not two circles/polygons of the
opposite direction as expected.

clf;
colormap ('default');
x = linspace (-2, 2);
[x, y] = meshgrid (x);
z = sqrt (x.^2 + y.^2) ./ (x.^2 + y.^2 + 1);
contourf (x, y, z, [0.4, 0.4]);
title ('Hole should be filled with the background color');

It is hard to post-process these small fragments in vector editors,
especially in real example with lot of contours, which needs to be stroked
and filled as a single object.

I can't confirm it, but Matlab output seems indirectly to be correct:
http://www.zhinst.com/blogs/schwizer/2010/11/contour-example/ (here it is
exported into SVG)

Any idea what to fix on my side?

Thanks, Jan

PS: 3.8.2 Win 7, Experimental GUI, configured for "i686-w64-mingw32".