From: "Bill Kelly" <billk / cts.com>
>
> I had planned to improve my solution by taking an approach
> similar to Justin Ethier's. . . . By iterating and "moving the
> circle center towards the outlier as the radius is reduced,
> while all points still are within the radius."
> 
> I may still code that if I have time... but then again, it's
> already been done. :)

Ah, what the heck... :)  Here 'tis..

http://tastyspleen.net/~billk/ruby/quiz/157-smallest-circle/157_smallest_circle.rb

# Algorithm used: First enclose the points in a simple
# axis-aligned bounding box, and choose the center of the
# box as the initial center of the circle. Then, binary
# search to determine how far we can move the center point
# toward the furthest outlying point, while keeping the
# rest of the points still inside the circle.


Regards,

Bill