The functions are all 'sql' functions. If you want to make these functions

executable by other people you will also have to make the referenced

cube functions executable. cube(text), cube_distance(cube,cube),

cube_ll_coord(cube,int) and cube_enlarge(cube,float8,int) are used indirectly

by the earth distance functions. is_point(cube) and cube_dim(cube) are used

in suggested constraints for data in domain earth. cube_ur_coord(cube,int)

is used in the regression tests and might be useful for looking at bounding

box coordinates in user applications.

A domain of type cube named earth is defined. Since check constraints

are not supported for domains yet, this isn't as useful as it might be.

However the checks that should be supplied to all data of type earth are:

constraint not_point check(is_point(earth))

constraint not_3d check(cube_dim(earth) <= 3)

constraint on_surface check(abs(cube_distance(earth, '(0)'::cube) /

earth() - 1) < '10e-12'::float8);

cube functions executable. cube(text), cube(float8), cube(cube,float8),

cube_distance(cube,cube), cube_ll_coord(cube,int) and

cube_enlarge(cube,float8,int) are used indirectly by the earth distance

functions. is_point(cube) and cube_dim(cube) are used in constraints for data

in domain earth. cube_ur_coord(cube,int) is used in the regression tests and

might be useful for looking at bounding box coordinates in user applications.

A domain of type cube named earth is defined.

There are constraints on it defined to make sure the cube is a point,

that it does not have more than 3 dimensions and that it is very near

the surface of a sphere centered about the origin with the radius of

the Earth.

The following functions are provided:

earth() - Returns the radius of theearth in meters.

earth() - Returns the radius of theEarth in meters.

sec_to_gc(float8) - Converts the normal straight line (secant) distance between

between two points on the surface of the Earth to the great circle distance

> look at to create these?

Here's the setup for adding an operator '<@>' to give distance in

statute miles between two points on theearth's surface. Coordinates

statute miles between two points on theEarth's surface. Coordinates

are in degrees. Points are taken as (longitude, latitude) and not vice

versa as longitude is closer to the intuitive idea of x-axis and

latitude to y-axis.

-- Define domain for locations on the surface of the earth using a cube

-- datatype with constraints. cube provides 3D indexing.

-- Check constraints aren't currently supported.

-- The cube is restricted to be a point, no more than 3 dimensions

-- (for less than 3 dimensions 0 is assumed for the missing coordinates)

-- and that the point must be very near the surface of the sphere

-- centered about the origin with the radius of the earth.

CREATE DOMAIN earth AS cube;

-- CONSTRAINT not_point check(is_point(earth))

-- CONSTRAINT not_3d check(cube_dim(earth) <= 3)

-- CONSTRAINT on_surface check(abs(cube_distance(earth, '(0)'::cube) /

-- earth() - 1) < '10e-12'::float8);

CREATE DOMAIN earth AS cube

CONSTRAINT not_point check(cube_is_point(value))

CONSTRAINT not_3d check(cube_dim(value) <= 3)

CONSTRAINT on_surface check(abs(cube_distance(value, '(0)'::cube) /

earth() - 1) < '10e-7'::float8);

CREATE OR REPLACE FUNCTION sec_to_gc(float8)

RETURNS float8

RETURNS earth

LANGUAGE 'sql'

IMMUTABLE STRICT

AS 'SELECT cube(\'(\'||earth()*cos(radians($1))*cos(radians($2))||\',\'||earth()*cos(radians($1))*sin(radians($2))||\',\'||earth()*sin(radians($1))||\')\')';

AS 'SELECT cube(cube(cube(earth()*cos(radians($1))*cos(radians($2))),earth()*cos(radians($1))*sin(radians($2))),earth()*sin(radians($1)))';

CREATE OR REPLACE FUNCTION latitude(earth)

RETURNS float8