[postgis-users] IsSimple doesn't work correctly?

[Michael Schiller]

Hello,  
 
I am using Postgis 0.8.1 with PostgreSQL 7.4.1 and GEOS 1.0.0 
 
I  tried the method IsSimple  and I think that it doesn't work correctly. 
 
select id, issimple(poly), poly from test; 
 id | issimple |                                                            
                                                                            
poly

----+----------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 
  1 | t        | SRID=-1;MULTIPOLYGON(((0 0,0 5,5 5,5 0,0 0))) 
  2 | t        | SRID=-1;MULTIPOLYGON(((0 5,0 10,5 10,5 5,0 5))) 
  3 | t        | SRID=-1;MULTIPOLYGON(((5 0,5 5,10 5,10 0,5 0))) 
  4 | t        | SRID=-1;MULTIPOLYGON(((5 5,5 10,10 10,10 5,5 5))) 
  5 | t        | SRID=-1;MULTIPOLYGON(((0 10,0 15,5 15,5 10,0 10))) 
  6 | t        | SRID=-1;MULTIPOLYGON(((10 0,10 5,15 5,15 0,10 0))) 
 10 | t        | SRID=-1;MULTIPOLYGON(((50 50,50 55,56 55,56 50,53 50,55
52,53 54,51 52,53 50,50 
50))) 
 11 | t        | SRID=-1;MULTIPOLYGON(((60 60,60 65,66 65,66 60,60 60),(63
60,61 62,63 64,65 62,63 
60))) 
 12 | t        | SRID=-1;MULTIPOLYGON(((70 70,70 76,74 76,74 70,70 70),(72
71,72 75,73 75,71 73,73 
71,72 71))) 
 13 | t        | SRID=-1;MULTIPOLYGON(((80 80,80 86,84 86,84 80,80 80),(82
81,82 82,83 81,82 81),(82 
82,81 83,82 84,82 82),(82 84,82 85,83 85,82 84))) 
 14 | t        | SRID=-1;MULTIPOLYGON(((90 90,90 96,94 96,94 90,90 90),(92
92,91 93,92 94,92 92))) 
 15 | t        | SRID=-1;MULTIPOLYGON(((100 100,100 105,105 105,105 100,100
100),(101 101,101 
102,102 102,102 101,101 101),(103 103,103 104,104 104,104 103,103
103)),((110 110,110 115,115 
115,115 110,110 110),(111 111,111 112,112 112,112 111,111 111),(113 113,113
114,114 114,114 
113,113 113))) 
 16 | t        | SRID=-1;MULTIPOLYGON(((121 120,121 124,123 124,120 122,123
120,121 120))) 
 17 | t        | SRID=-1;MULTIPOLYGON(((130 130,132 132,130 132,132 130,130
130))) 
 18 | t        | SRID=-1;MULTIPOLYGON(((140 141,140 144,143 144,143 141,140
141),(142 140,141 
142,142 143,142 140))) 
 19 | t        | SRID=-1;MULTIPOLYGON(((150 150,150 154,156 154,156 150,150
150),(153 150,151 
152,153 154,155 152,153 150))) 
 20 | t        | SRID=-1;MULTIPOLYGON(((160 160,160 164,163 164,161 162,163
160,160 160)),((163 
160,165 162,163 164,166 164,166 160,163 160))) 
(17 rows) 
 
There are some Polygons in this Example that are not simple (id = 10, id =
12, id = 16, id = 17, id = 18, 
id = 19).  
The Method IsSimple answers only with true. 
 
Where is the error? 
 
thanks, Mich 

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