Distance between two GPS points

Question

Is there an inbuilt function in PL/SQL for calulating the distance between two GPS (lat/long) points?
I'm using Oracle 9i. There's a thing called SDO_GEOM available, but I'm not sure if this is what its used for or if it's the best option.

Answer 1

If the earth is a complete globe and its circumference is 40000km,
I make the function as follows.
create ore replace
function distance
(a_lat number,a_lon number,b_lat number, b_lon number)
return number is
circum number := 40000; -- kilometers
pai number := acos(-1);
a_nx number;
a_ny number;
a_nz number;
b_nx number;
b_ny number;
b_nz number;
inner_product number;
begin
if (a_lat=b_lat) and (a_lon=b_lon) then
return 0;
else
a_nx := cos(a_lat*pai/180) * cos(a_lon*pai/180);
a_ny := cos(a_lat*pai/180) * sin(a_lon*pai/180);
a_nz := sin(a_lat*pai/180);
b_nx := cos(b_lat*pai/180) * co s(b_lon*pai/180);
b_ny := cos(b_lat*pai/180) * sin(b_lon*pai/180);
b_nz := sin(b_lat*pai/180);
inner_product := a_nx*b_nx + a_ny*b_ny + a_nz*b_nz;
if inner_product > 1 then
return 0;
else
return (circum*acos(inner_product))/(2*pai);
end if;
end if;
end;
I rewrite it by using the factorization and the triangle function's sum and difference formulas:
cos(x-y) = cos(x)cos(y)+sin(x)sin(y)
As result, this function is same to the 1st method of Billy Verreynne.
create or replace
function distance
(a_lat number,a_lon number,b_lat number, b_lon number)
return number is
circum number := 40000; -- kilometers
pai number := acos(-1);
dz number;
dx2y2 number;
inner_product number;
begin
if (a_lat=b_lat) and (a_lon=b_lon) then
return 0;
else
dz := sin(a_lat*pai/180)*sin(b_lat*pai/180);
dx2y2 := cos(a_lat*pai/180)*cos(b_lat*pai/180)*cos((a_lon-b_lon)*pai/180);
inner_product := dz*dz + dx2y2;
if inner_product > 1 then
return 0;
else
return (circum*acos(inner_product))/(2*pai);
end if;
end if;
end;
Message was edited by:
ushitaki