[postgis-tickets] [PostGIS] #5563: Potential bug in the ST_Equals function.

[PostGIS]

#5563: Potential bug in the ST_Equals function.
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  Reporter:  Wenjing   |      Owner:  pramsey
      Type:  defect    |     Status:  new
  Priority:  critical  |  Milestone:  PostGIS 3.4.1
 Component:  postgis   |    Version:  3.4.x
Resolution:            |   Keywords:
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Comment (by mdavis):

 The issue is due to the inherent inaccuracy of finite-precision floating
 point arithmetic. There's a lot of arithmetic being carried out, so the
 likelihood of 2 transformed intersecting lines NOT intersecting in 3D is
 very high.

 You can't rely on topological relationships being preserved through
 floating-point operations. This is the essence of the well-known issue of
 geometrical robustness failures. The solution is usually either to use
 exact arithmetic (often impractical) or use tolerance values (not a
 panacea, but very often works).
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Ticket URL: <https://trac.osgeo.org/postgis/ticket/5563#comment:3>
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