I have included fixes to declare some floating point constants as double

instead of int, change the calculation method to use the haversine
formula
which is more accurrate for short distances, added a grant to public for
geo_distance and added a regression test.

I will resubmit the earth distance stuff based on cube after 7.3 is
released.

Bruno Wolff III

diff --git a/contrib/earthdistance/Makefile b/contrib/earthdistance/Makefile
index 94ad370d599cbccde6bfd3a408d5c5d1c26bce79..49d1505f0418ee2e2c070283687b8da0ee307fbc 100644 (file)
--- a/contrib/earthdistance/Makefile
+++ b/contrib/earthdistance/Makefile
@@ -1,4 +1,4 @@
-# $Header: /cvsroot/pgsql/contrib/earthdistance/Makefile,v 1.11 2001/09/06 10:49:29 petere Exp $
+# $Header: /cvsroot/pgsql/contrib/earthdistance/Makefile,v 1.12 2002/09/20 03:47:22 momjian Exp $
 
 subdir = contrib/earthdistance
 top_builddir = ../..
@@ -7,5 +7,6 @@ include $(top_builddir)/src/Makefile.global
 MODULES = earthdistance
 DATA_built = earthdistance.sql
 DOCS = README.earthdistance
+REGRESS = earthdistance
 
 include $(top_srcdir)/contrib/contrib-global.mk

diff --git a/contrib/earthdistance/README.earthdistance b/contrib/earthdistance/README.earthdistance
index f4ecef80fef74847bc930f10f09770bac999ff1c..2ed5c2816595c30c726bfbcff48a83c56a5fb284 100644 (file)
--- a/contrib/earthdistance/README.earthdistance
+++ b/contrib/earthdistance/README.earthdistance
@@ -1,3 +1,13 @@
+---------------------------------------------------------------------
+I corrected a bug in the geo_distance code where two double constants
+were declared as int. I changed the distance function to use the
+haversine formula which is more accurate for small distances.
+I added a regression test to the package. I added a grant statement
+to give execute access for geo_distance to public.
+
+Bruno Wolff III
+September 2002
+---------------------------------------------------------------------
 Date: Wed, 1 Apr 1998 15:19:32 -0600 (CST)
 From: Hal Snyder <hal@vailsys.com>
 To: vmehr@ctp.com

diff --git a/contrib/earthdistance/earthdistance.c b/contrib/earthdistance/earthdistance.c
index c1962272f4fb64775e21a858d40f43d9f6dbee02..f069edf13102fde6b629e0e01a3141c4254bd1dd 100644 (file)
--- a/contrib/earthdistance/earthdistance.c
+++ b/contrib/earthdistance/earthdistance.c
@@ -6,8 +6,8 @@
 
 
 /* Earth's radius is in statute miles. */
-const int      EARTH_RADIUS = 3958.747716;
-const int      TWO_PI = 2.0 * M_PI;
+const double   EARTH_RADIUS = 3958.747716;
+const double   TWO_PI = 2.0 * M_PI;
 
 double    *geo_distance(Point *pt1, Point *pt2);
 
@@ -50,6 +50,7 @@ geo_distance(Point *pt1, Point *pt2)
                                long2,
                                lat2;
        double          longdiff;
+        double         sino;
        double     *resultp = palloc(sizeof(double));
 
        /* convert degrees to radians */
@@ -65,8 +66,10 @@ geo_distance(Point *pt1, Point *pt2)
        if (longdiff > M_PI)
                longdiff = TWO_PI - longdiff;
 
-       *resultp = EARTH_RADIUS * acos
-               (sin(lat1) * sin(lat2) + cos(lat1) * cos(lat2) * cos(longdiff));
+        sino = sqrt(sin(fabs(lat1-lat2)/2.)*sin(fabs(lat1-lat2)/2.) +
+                cos(lat1) * cos(lat2) * sin(longdiff/2.)*sin(longdiff/2.));
+        if (sino > 1.) sino = 1.;
+        *resultp = 2. * EARTH_RADIUS * asin(sino);
 
        return resultp;
 }

diff --git a/contrib/earthdistance/earthdistance.sql.in b/contrib/earthdistance/earthdistance.sql.in
index 087484da5158dae95dcdd87a9e530f92f98fbae6..04485589c74f7041f6a3b062ef3f303fa4f0f9bf 100644 (file)
--- a/contrib/earthdistance/earthdistance.sql.in
+++ b/contrib/earthdistance/earthdistance.sql.in
@@ -1,16 +1,12 @@
+begin;
 
 --------------- geo_distance
 
-DROP FUNCTION geo_distance (point, point);
-CREATE FUNCTION geo_distance (point, point) RETURNS float8
-  AS 'MODULE_PATHNAME' LANGUAGE 'c'
-  WITH (isstrict);
-
-SELECT geo_distance ('(1,2)'::point, '(3,4)'::point);
+CREATE OR REPLACE FUNCTION geo_distance (point, point) RETURNS float8
+  LANGUAGE 'c' IMMUTABLE STRICT AS 'MODULE_PATHNAME';
 
 --------------- geo_distance as operator <@>
 
-DROP OPERATOR <@> (point, point);
 CREATE OPERATOR <@> (
   leftarg = point,
   rightarg = point,
@@ -18,7 +14,11 @@ CREATE OPERATOR <@> (
   commutator = <@>
 );
 
--- ( 87.6, 41.8) is in Chicago
--- (106.7, 35.1) is in Albuquerque
--- The cities are about 1100 miles apart
-SELECT '(87.6,41.8)'::point <@> '(106.7,35.1)'::point;
+--
+-- By default this function is made executable by anyone. To restrict
+-- access by default, comment out the following grant command.
+--
+
+grant execute on function geo_distance(point, point) to public;
+
+commit;