--
-- CIRCLE
--
CREATE TABLE CIRCLE_TBL (f1 circle);
INSERT INTO CIRCLE_TBL VALUES ('<(0,0),3>');
INSERT INTO CIRCLE_TBL VALUES ('<(1,2),100>');
INSERT INTO CIRCLE_TBL VALUES ('1,3,5');
INSERT INTO CIRCLE_TBL VALUES ('((1,2),3)');
INSERT INTO CIRCLE_TBL VALUES ('<(100,200),10>');
INSERT INTO CIRCLE_TBL VALUES ('<(100,0),100>');
-- bad values
INSERT INTO CIRCLE_TBL VALUES ('<(-100,0),-100>');
ERROR:  Bad circle external representation '<(-100,0),-100>'
INSERT INTO CIRCLE_TBL VALUES ('1abc,3,5');
ERROR:  Bad circle external representation '1abc,3,5'
INSERT INTO CIRCLE_TBL VALUES ('(3,(1,2),3)');
ERROR:  Bad circle external representation '(3,(1,2),3)'
SELECT * FROM CIRCLE_TBL;
       f1       
----------------
 <(0,0),3>
 <(1,2),100>
 <(1,3),5>
 <(1,2),3>
 <(100,200),10>
 <(100,0),100>
(6 rows)

SELECT '' AS six, center(f1) AS center
  FROM CIRCLE_TBL;
 six |  center   
-----+-----------
     | (0,0)
     | (1,2)
     | (1,3)
     | (1,2)
     | (100,200)
     | (100,0)
(6 rows)

SELECT '' AS six, radius(f1) AS radius
  FROM CIRCLE_TBL;
 six | radius 
-----+--------
     |      3
     |    100
     |      5
     |      3
     |     10
     |    100
(6 rows)

SELECT '' AS six, diameter(f1) AS diameter
  FROM CIRCLE_TBL;
 six | diameter 
-----+----------
     |        6
     |      200
     |       10
     |        6
     |       20
     |      200
(6 rows)

SELECT '' AS two, f1 FROM CIRCLE_TBL WHERE radius(f1) < 5;
 two |    f1     
-----+-----------
     | <(0,0),3>
     | <(1,2),3>
(2 rows)

SELECT '' AS four, f1 FROM CIRCLE_TBL WHERE diameter(f1) >= 10;
 four |       f1       
------+----------------
      | <(1,2),100>
      | <(1,3),5>
      | <(100,200),10>
      | <(100,0),100>
(4 rows)

SELECT '' as five, c1.f1 AS one, c2.f1 AS two, (c1.f1 <-> c2.f1) AS distance
  FROM CIRCLE_TBL c1, CIRCLE_TBL c2
  WHERE (c1.f1 < c2.f1) AND ((c1.f1 <-> c2.f1) > 0)
  ORDER BY distance, one, two;
 five |      one       |      two       |     distance     
------+----------------+----------------+------------------
      | <(100,200),10> | <(100,0),100>  |               90
      | <(100,200),10> | <(1,2),100>    | 111.370729772479
      | <(1,3),5>      | <(100,200),10> | 205.476756144497
      | <(1,2),3>      | <(100,200),10> | 208.370729772479
      | <(0,0),3>      | <(100,200),10> | 210.606797749979
(5 rows)