What is the behavior of 'polybool' with NaN-delimited Input?

When I call polybool as follows, I get empty intersections, as expected:

[x,y]=polybool('&',...
[0,0,1,0],...
[0,1,0,0],...
[0,1,1,0],...
[1,1,0,1])

[x,y]=polybool('&',...
[0,1,1,0],...
[1,1,0,1],...
[0,0,1,0],...
[0,1,0,0])

When I combined the x & y inputs from both calls with a NaN in between, I expected the call to polybool to process the above computations in parallel.  Instead I got a nonempty intersection. 

Answer 1

[MathWorks Support Team]

Although the documentation is not as clear, this is expected behavior.  When a polygon is represented as a Nan-delimited vector, the NaNs separate the contours of a single polygon.  An equivalent way of writing this would be to use a cell array containing vectors of the contour.