From 24bebf0b725e965ed2b725dcb31a46f787e98dbf Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Fri, 20 Sep 2002 03:47:22 +0000
Subject: [PATCH] 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
---
contrib/earthdistance/Makefile | 3 ++-
contrib/earthdistance/README.earthdistance | 10 ++++++++++
contrib/earthdistance/earthdistance.c | 11 +++++++----
contrib/earthdistance/earthdistance.sql.in | 22 +++++++++++-----------
4 files changed, 30 insertions(+), 16 deletions(-)
diff --git a/contrib/earthdistance/Makefile b/contrib/earthdistance/Makefile
index 94ad370d599..49d1505f041 100644
--- 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 f4ecef80fef..2ed5c281659 100644
--- 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 c1962272f4f..f069edf1310 100644
--- 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 087484da515..04485589c74 100644
--- 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;
--
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