Also, D cannot be freely chosen, because some positions of D will make 
ABCDA not minimal.

    isconvex =. ([: ({. *./@:= }.) [: * 1 (-/ . *)@(1 1 1&,)\. ])"2

    (+/ % #) isconvex sortloops (?.10000 4 2$1000)
0.6959
    (+/ % #) isconvex sortloops (?10000 4 2$1000)
0.6911
    (+/ % #) isconvex sortloops (?10000 4 2$1000)
0.6847

close to 1 - 1%pi.

Henry Rich


Boyko Bantchev wrote:
> 2008/12/10 John Randall <[EMAIL PROTECTED]>:
>> My initial thought is this: Draw the first 3 sides A->B->C.  Let D be the
>> other vertex.  Then ABCD is convex iff D lies on the opposite side of the
>> line AC from B.  This gives probability at least 1/2 for your question.
> 
> ABCD will still be concave if D is, e.g., on the opposite side of BC from A.
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
> 
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm

Reply via email to