[postgis-devel] [PostGIS] #1975: ST_Equals returns false on result of calling ST_Shift_Longitude twice with date line longitude

[PostGIS]

#1975: ST_Equals returns false on result of calling ST_Shift_Longitude twice with
date line longitude
---------------------------+------------------------------------------------
 Reporter:  realityexists  |       Owner:  pramsey      
     Type:  defect         |      Status:  new          
 Priority:  medium         |   Milestone:  PostGIS 2.1.0
Component:  postgis        |     Version:  trunk        
 Keywords:                 |  
---------------------------+------------------------------------------------
 r10194, PostgreSQL 9.1.4, Windows 7 x64

 If I understand ST_Shift_Longitude correctly calling it twice is supposed
 to return the original value. Doing a text comparison on the return value
 seems to confirm this, ''but'' ST_Equals returns false when there is a 180
 longitude in the shape.

 Try this to reproduce:
 {{{
 WITH data AS
 (
         SELECT ST_GeomFromText('POLYGON((170 54,180 60,-172 64,-168 65,170
 54))', 4326) AS shape
 )
 , ops AS
 (
         SELECT shape, ST_Shift_Longitude(ST_Shift_Longitude(shape)) AS
 reshifted
         FROM data
 )
 SELECT ST_Equals(shape, reshifted), ST_AsEWKT(shape) =
 ST_AsEWKT(reshifted) AS text_equals
 FROM ops
 }}}

 st_equals is false, but text_equals is true.

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/1975>
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