[R-sig-Geo] Diameter of a polygon

[Karl Ove Hufthammer]

Is it possible to easily calculate the diameter of a (large) polygon, 
i.e. the longest distance between two points of the polygon? For a 
rectangle, this would be the length of a diagonal.

The two points need not be actual vertices of the polygons (or must they 
necessarily be so?).

I’m also interested in the shortest length. For a rectangle, this would be 
the length of the shortest side.

And perhaps also the longest line that can be placed inside the polygon. 
Note that this may easily be shorter than the longest diameter, as the 
corresponding diameter line may pass outside the polygon. (Though I guess 
for the *shortest* line, it would be identical to the smallest diameter.)

A quick rseek.org search didn’t turn up anything relevant.

-- 
Karl Ove Hufthammer