[mlpack] Numeric sensitivity of RangeSearch

[Ryan Curtin]

On Tue, Mar 25, 2014 at 09:55:17PM +0800, Li Dong wrote:
> Dear Ryan,
> 
> I have isolated a bug case into a single code in the attachment, from which you can see the results:
> 
> Neighbor grid number is 201 when R is 1.
> Neighbor grid number is 102 when R is 6.371e+06.

Hi Li,

Thank you for the easy code sample.  In the code you have written:

  typedef mlpack::tree::BinarySpaceTree<
      mlpack::bound::HRectBound<2>,
      mlpack::range::RangeSearchStat> TreeType;
  typedef mlpack::metric::SquaredEuclideanDistance MetricType;
  typedef mlpack::range::RangeSearch<MetricType, TreeType> Searcher;

If you change SquaredEuclideanDistance to EuclideanDistance, the problem
is solved.  I noticed that the tutorial [1] suggests using the
SquaredEuclideanDistance class, but this is no longer correct based on
the pruning rules that the RangeSearch class uses.

I have fixed the tutorials in r16378 and r16379 and am in the process of
rebuilding them for the website.  I am sorry for the errors in the
tutorials.

Thanks,

Ryan

-- 
Ryan Curtin    | "I am."
ryan at ratml.org |   - Joe