[math-fun] n-D median redefined

My friend Richard Harter redefined my median in what may be a nicer way:

We use the sum of absolute distances function,

f(x) = sum(abs(x-x_i))

and find the set of x's such f(x) is a minimum. All of these are valid medians; however the centroid of the set is in some sense the most central median.

--Steve