Computes the minimum-area convex k-gon (k-sided polygon) that circumscribes the given convex n-gon. Follows the method of Aggarwal et al, "Minimum area circumscribing Polygons", The Visual Computer (1985) 1:112-117
Example:
IDL> x = [43, 18, 19, 24, 35, 49, 56, 54]*1.
IDL> y = [24, 45, 54, 63, 69, 64, 57, 41]*1.
IDL> result = POLY_KGON(x, y, kgon=4)
IDL> print, result
15.2727 47.2909
28.6026 71.2848
64.4083 58.4970
43.5917 23.5030