text: --
  -- POLYGON
  --
  -- polygon logic
  --
  
  CREATE TABLE POLYGON_TBL(f1 polygon);
  
  
  INSERT INTO POLYGON_TBL(f1) VALUES ('(2.0,0.0),(2.0,4.0),(0.0,0.0)');
  
  INSERT INTO POLYGON_TBL(f1) VALUES ('(3.0,1.0),(3.0,3.0),(1.0,0.0)');
  
  -- degenerate polygons
  INSERT INTO POLYGON_TBL(f1) VALUES ('(0.0,0.0)');
  
  INSERT INTO POLYGON_TBL(f1) VALUES ('(0.0,1.0),(0.0,1.0)');
  
  -- bad polygon input strings
  INSERT INTO POLYGON_TBL(f1) VALUES ('0.0');
  
  INSERT INTO POLYGON_TBL(f1) VALUES ('(0.0 0.0');
  
  INSERT INTO POLYGON_TBL(f1) VALUES ('(0,1,2)');
  
  INSERT INTO POLYGON_TBL(f1) VALUES ('(0,1,2,3');
  
  INSERT INTO POLYGON_TBL(f1) VALUES ('asdf');
  
  
  SELECT '' AS four, * FROM POLYGON_TBL;
  
  -- overlap
  SELECT '' AS three, p.*
     FROM POLYGON_TBL p
     WHERE p.f1 && '(3.0,1.0),(3.0,3.0),(1.0,0.0)';
  
  -- left overlap
  SELECT '' AS four, p.*
     FROM POLYGON_TBL p
     WHERE p.f1 &< '(3.0,1.0),(3.0,3.0),(1.0,0.0)';
  
  -- right overlap
  SELECT '' AS two, p.*
     FROM POLYGON_TBL p
     WHERE p.f1 &> '(3.0,1.0),(3.0,3.0),(1.0,0.0)';
  
  -- left of
  SELECT '' AS one, p.*
     FROM POLYGON_TBL p
     WHERE p.f1 << '(3.0,1.0),(3.0,3.0),(1.0,0.0)';
  
  -- right of
  SELECT '' AS zero, p.*
     FROM POLYGON_TBL p
     WHERE p.f1 >> '(3.0,1.0),(3.0,3.0),(1.0,0.0)';
  
  -- contained
  SELECT '' AS one, p.*
     FROM POLYGON_TBL p
     WHERE p.f1 <@ polygon '(3.0,1.0),(3.0,3.0),(1.0,0.0)';
  
  -- same
  SELECT '' AS one, p.*
     FROM POLYGON_TBL p
     WHERE p.f1 ~= polygon '(3.0,1.0),(3.0,3.0),(1.0,0.0)';
  
  -- contains
  SELECT '' AS one, p.*
     FROM POLYGON_TBL p
     WHERE p.f1 @> polygon '(3.0,1.0),(3.0,3.0),(1.0,0.0)';
  
  --
  -- polygon logic
  --
  -- left of
  SELECT polygon '(2.0,0.0),(2.0,4.0),(0.0,0.0)' << polygon '(3.0,1.0),(3.0,3.0),(1.0,0.0)' AS false;
  
  -- left overlap
  SELECT polygon '(2.0,0.0),(2.0,4.0),(0.0,0.0)' << polygon '(3.0,1.0),(3.0,3.0),(1.0,0.0)' AS true;
  
  -- right overlap
  SELECT polygon '(2.0,0.0),(2.0,4.0),(0.0,0.0)' &> polygon '(3.0,1.0),(3.0,3.0),(1.0,0.0)' AS false;
  
  -- right of
  SELECT polygon '(2.0,0.0),(2.0,4.0),(0.0,0.0)' >> polygon '(3.0,1.0),(3.0,3.0),(1.0,0.0)' AS false;
  
  -- contained in
  SELECT polygon '(2.0,0.0),(2.0,4.0),(0.0,0.0)' <@ polygon '(3.0,1.0),(3.0,3.0),(1.0,0.0)' AS false;
  
  -- contains
  SELECT polygon '(2.0,0.0),(2.0,4.0),(0.0,0.0)' @> polygon '(3.0,1.0),(3.0,3.0),(1.0,0.0)' AS false;
  
  SELECT '((0,4),(6,4),(1,2),(6,0),(0,0))'::polygon @> '((2,1),(2,3),(3,3),(3,1))'::polygon AS "false";
  
  SELECT '((0,4),(6,4),(3,2),(6,0),(0,0))'::polygon @> '((2,1),(2,3),(3,3),(3,1))'::polygon AS "true";
  
  SELECT '((1,1),(1,4),(5,4),(5,3),(2,3),(2,2),(5,2),(5,1))'::polygon @> '((3,2),(3,3),(4,3),(4,2))'::polygon AS "false";
  
  SELECT '((0,0),(0,3),(3,3),(3,0))'::polygon @> '((2,1),(2,2),(3,2),(3,1))'::polygon AS "true";
  
  -- same
  SELECT polygon '(2.0,0.0),(2.0,4.0),(0.0,0.0)' ~= polygon '(3.0,1.0),(3.0,3.0),(1.0,0.0)' AS false;
  
  -- overlap
  SELECT polygon '(2.0,0.0),(2.0,4.0),(0.0,0.0)' && polygon '(3.0,1.0),(3.0,3.0),(1.0,0.0)' AS true;
  
  SELECT '((0,4),(6,4),(1,2),(6,0),(0,0))'::polygon && '((2,1),(2,3),(3,3),(3,1))'::polygon AS "true";
  
  SELECT '((1,4),(1,1),(4,1),(4,2),(2,2),(2,4),(1,4))'::polygon && '((3,3),(4,3),(4,4),(3,4),(3,3))'::polygon AS "false";
  SELECT '((200,800),(800,800),(800,200),(200,200))' &&  '(1000,1000,0,0)'::polygon AS "true";
  
  -- distance from a point
  SELECT	'(0,0)'::point <-> '((0,0),(1,2),(2,1))'::polygon as on_corner,
  	'(1,1)'::point <-> '((0,0),(2,2),(1,3))'::polygon as on_segment,
  	'(2,2)'::point <-> '((0,0),(1,4),(3,1))'::polygon as inside,
  	'(3,3)'::point <-> '((0,2),(2,0),(2,2))'::polygon as near_corner,
  	'(4,4)'::point <-> '((0,0),(0,3),(4,0))'::polygon as near_segment;
  