>> sumsq(bsxfun(@minus, X(1,:), initial_centroids))
ans =

   56.5491    9.5377

>>
ans =

  -1.15792   1.60757
  -4.15792   2.60757
  -6.15792  -0.39243

>> sumsq(bsxfun(@minus, X(1,:), initial_centroids), 2)
ans =

    3.9251
   24.0877
   38.0740

>> [x, xid] = min(sumsq(bsxfun(@minus, X(1,:), initial_centroids), 2));
>> [x, xid] = min(sumsq(bsxfun(@minus, X(1,:), initial_centroids), 2))
x =  3.9251
xid =  1