Re: [Boost-bugs] [Boost C++ Libraries] #7813: Bug in boost::geometry::centroid with trivially small polygons

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #7813: Bug in boost::geometry::centroid with trivially small polygons
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-12-22 18:02:36

#7813: Bug in boost::geometry::centroid with trivially small polygons
-------------------------------+--------------------------------------------
  Reporter:  anonymous         |       Owner:  barendgehrels
      Type:  Bugs              |      Status:  closed       
 Milestone:  To Be Determined  |   Component:  geometry     
   Version:  Boost 1.52.0      |    Severity:  Problem      
Resolution:  wontfix           |    Keywords:               
-------------------------------+--------------------------------------------
Changes (by barendgehrels):

  * status:  reopened => closed
  * resolution:  => wontfix

Comment:

 I reproduced the problem. The polygon is indeed very small, near the
 limits of floating point resolution. The division (used for centroid) by a
 similar small value results in the centroid being outside the polygon.

 If you really want to use results for this resolution, please use
 ttmath_big. The problem is than not there.

 Summary:

 centroid (double) is: POINT(139.6527006820726300 35.8585406437098440)

 centroid (ttmath) is: POINT(139.64437785388127853881278548429355447
 35.85640358447488584474885847218077831)

 centroid (sql server) is: POINT (139.64437785388145 35.856403584474876)

 So the double-version is indeed a bit off, and indeed outside the convex
 polygon.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/7813#comment:4>
Boost C++ Libraries <http://www.boost.org/>
Boost provides free peer-reviewed portable C++ source libraries.