Finding centre and radius of a circular geometry

 CREATE OR REPLACE
 FUNCTION FindCircle (p_polygon IN mdsys.sdo_geometry)
   RETURN mdsys.sdo_point_type deterministic
 IS
   v_centre  mdsys.sdo_point_type;
   v_pt1     mdsys.vertex_type;
   v_pt2     mdsys.vertex_type;
   v_pt3     mdsys.vertex_type;
   dA        NUMBER;
   dB        NUMBER;
   dC        NUMBER;
   dD        NUMBER;
   dE        NUMBER;
   dF        NUMBER;
   dG        NUMBER;
 BEGIN
   IF (p_polygon IS NULL) THEN
      RETURN NULL;
   END IF;
   IF (p_polygon.get_gtype() NOT IN (3,7) ) THEN
      RETURN NULL;
   END IF;
   -- Grab first three vertices for checking
   --
   v_pt1 := mdsys.sdo_util.getVertices(p_polygon)(1);
   v_pt2 := mdsys.sdo_util.getVertices(p_polygon)(2);
   v_pt3 := mdsys.sdo_util.getVertices(p_polygon)(3);
   dA := v_pt2.X - v_pt1.X;
   dB := v_pt2.Y - v_pt1.Y;
   dC := v_pt3.X - v_pt1.X;
   dD := v_pt3.Y - v_pt1.Y;
   dE := dA * (v_pt1.X + v_pt2.X) + dB * (v_pt1.Y + v_pt2.Y);
   dF := dC * (v_pt1.X + v_pt3.X) + dD * (v_pt1.Y + v_pt3.Y);
   dG := 2.0 * (dA * (v_pt3.Y - v_pt2.Y) - dB * (v_pt3.X - v_pt2.X));
   -- If dG is zero then the three points are collinear and no finite-radius
   -- circle through them exists.
   IF ( dG = 0 ) THEN
       RETURN NULL;
   ELSE
       v_centre := NEW mdsys.sdo_point_type((dD * dE - dB * dF) / dG,
                                            (dA * dF - dC * dE) / dG,
                                            NULL);
       v_centre.Z := SQRT(POWER(v_pt1.X - v_centre.X,2) + POWER(v_pt1.Y - v_centre.Y,2) );
       RETURN v_centre;
   END IF;
 END FindCircle;

 SELECT codesys.findCircle(mdsys.sdo_geom.sdo_buffer(mdsys.sdo_geometry(2001,NULL,sdo_point_type(10,10,NULL),NULL,NULL),10,0.02)) AS centre
   FROM dual;
 .
 CENTRE
 ------------------------------
 MDSYS.SDO_POINT_TYPE(10,10,10)
 .
 SELECT codesys.findCircle(SDO_GEOMETRY (2003, NULL, NULL, SDO_ELEM_INFO_ARRAY (1,1003,4),SDO_ORDINATE_ARRAY (15,145, 10,150, 20,150))) AS centre
   FROM dual;
 .
 CENTRE
 ------------------------------
 MDSYS.SDO_POINT_TYPE(15,150,5)
 .

 SELECT roundOrdinates(mdsys.sdo_util.CIRCLE_POLYGON(10,10,10,1),8) AS circle
   FROM dual;
 .
 CIRCLE
 --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 MDSYS.SDO_GEOMETRY(2003,8307,NULL,MDSYS.SDO_ELEM_INFO_ARRAY(1,1003,1),MDSYS.SDO_ORDINATE_ARRAY(10,9.99991007,10.00006457,9.99993641,10.00009132,10,10.00006457,10.00006359,10,10.00008993,9.99993543,10.00006359,9.99990868,10,9.99993543,9.99993641,10,9.99991007))
 .
 SELECT round(a.centre.x,8) AS cx,
        round(a.centre.y,8) AS cy,
        round(sdo_geom.sdo_distance(mdsys.sdo_geometry(2001,8307,mdsys.sdo_point_type(a.centre.x,           a.centre.y,NULL),NULL,NULL),
                                    mdsys.sdo_geometry(2001,8307,mdsys.sdo_point_type(a.centre.x+a.centre.z,a.centre.y,NULL),NULL,NULL),
                                    0.005),3) AS radius
   FROM (SELECT findCircle(roundOrdinates(mdsys.sdo_util.CIRCLE_POLYGON(10,10,10,1),8)) AS centre
           FROM dual ) a;
 .
 CX          CY          RADIUS
 ----------- ----------- ------
 10.00000068 10.00000071 9.938
 .
 -- Or.....
 SELECT round(f.centre.x,8) AS cx,
        round(f.centre.y,8) AS cy,
        round(f.centre.z,1) AS radius
   FROM (SELECT sdo_cs.transform(mdsys.sdo_geometry(2001,28355,
                                                    mdsys.sdo_point_type(b.centre.x,
                                                                         b.centre.y,
                                                                         b.centre.z),
                                                    NULL,NULL),8307).sdo_point AS centre
           FROM (SELECT a.geom,findCircle(sdo_cs.transform(a.geom,28355)) AS centre
                   FROM (SELECT mdsys.sdo_util.CIRCLE_POLYGON(147,-32,10,1) AS geom
                           FROM dual ) a
                 ) b
         ) f;
 .
 CX           CY           RADIUS
 ------------ ------------ ------
 147.00000026 -31.99999978 10