Automated method and system to calculate the surface distance between two geographical locations, and to filter a data set based on the calculation

1. An automated method comprising:

determining, using look-up tables, a surface distance between two geographical locations by,

storing values in a square look-up table for determining the square of a value;

storing values in a squared linear to surface distance look-up table for determining the surface distance of a linear value;

using Normalized Cartesian co-ordinates of the two geographic locations and the square look-up table to calculate the square of the linear distance between the two geographical locations, the Normalized Cartesian co-ordinates obtained by adding to each of Cartesian co-ordinates X, Y, and Z a value of earth radius;

using the squared linear to surface distance look-up table to convert the calculated square of the linear distance between the two geographical locations to a surface distance value between the two geographical locations; and

outputting the surface distance value between the two geographical locations.

2. The method of claim 1 further including calculating Normalized Cartesian co-ordinates of the two geographic locations, by converting the two geographical locations to Normalized Cartesian co-ordinates.

3. The method of claim 1 further including receiving a request from a user to calculate the distance between two geographical locations.

4. The method of claim 1 further including receiving distance criteria from a user and determining if the surface distance falls within the distance criteria.

5. The method of claim 1 further including: if the calculated surface distance is a distance greater than the surface distance of the diameter of the Earth, then recalculating the surface distance by:

determining the location of a point on the Earth's surface diametrically opposite one of the two geographic locations;

calculating the surface distance from the diametrically opposite point to the other of the two geographical locations; and

subtracting the calculated surface distance from the surface distance of the Earth's diameter to more accurately calculate the distance between the two geographic locations.

6. A machine-readable medium comprising instructions, which when executed by a machine, cause the machine to perform a method comprising:

determining the surface distance between two geographical locations by,

storing values in a square look-up table for determining the square of a value;

storing values in a squared linear to surface distance look-up table for determining the surface distance of a linear value;

receiving a request to calculate the distance between two geographical locations;

using Normalized Cartesian co-ordinates of the two geographic locations and the square look-up table to calculate the square of the linear distance between the two geographical locations, the Normalized Cartesian co-ordinates obtained by adding to each of Cartesian co-ordinates X, Y, and Z a value of earth radius;

using the squared linear to surface distance look-up table to convert the calculated square of the linear distance between the two geographical locations to a surface distance value between the two geographical locations; and

outputting the surface distance value between the two geographical locations.

7. A computerized system to calculate, using look-up tables, a surface distance between two geographical locations, the system comprising:

a database to store values in a square look-up table for determining the square of a value, and values in a squared linear to surface distance look-up table for determining the surface distance of the square of a linear value;

a processor to use Normalized Cartesian co-ordinates of the two geographic locations and the square look-up table to calculate the square of the linear distance between the two geographical locations, and to use the squared linear to surface distance look-up table to convert the calculated square of the linear distance between the two geographical locations to a surface distance value between the two geographical locations, the Normalized Cartesian co-ordinates obtained by adding to each of Cartesian co-ordinates X, Y, and Z a value of earth radius; and

an output device to output the surface distance value between the two geographical locations.

8. A computerized system to calculate, using look-up tables, a surface distance between two geographical locations, the system comprising:

first means for storing values in a square look-up table for determining the square of a value, and values in a squared linear to surface distance look-up table for determining the surface distance of a square of a linear value;

second means for using Normalized Cartesian co-ordinates of the two geographic locations and the square look-up table to calculate the square of the linear distance between the two geographical locations, and for using the squared linear to surface distance look-up table to convert the calculated square of the linear distance between the two geographical locations to a surface distance value between the two geographical locations, the Normalized Cartesian co-ordinates obtained by adding to each of Cartesian co-ordinates X, Y, and Z a value of earth radius; and

third means for outputting surface distance value between the two geographical locations.

9. A method to filter a search result set using distance criteria, the method including:

receiving a search request with search parameters, the search request including distance criteria;

retrieving a result using the search parameters, the result including a list of items and associated geographical locations;

determining Normalized Cartesian co-ordinates for an origin location, the Normalized Cartesian co-ordinates obtained by adding to each of Cartesian co-ordinates X, Y, and Z a value of earth radius;

determining the Normalized Cartesian co-ordinates for the geographical location associated with each of the items;

using the Normalized Cartesian co-ordinates of the origin location and of the geographical location associated with each of the items to calculate a linear distance from the origin location to the geographical location of each of the items;

converting the calculated linear distances to surface distances from the origin location to the geographical location of each of the items;

determining whether the surface distance from the origin location to the geographical location of an item falls within the distance criteria;

for cases where it is determined the surface distance from the origin location to the geographical location of an item falls within the distance criteria then including the item in a result set; and

outputting the result set.

10. The method of claim 9 further including:

storing values in a square look-up table for determining the square of a value;

storing values in a squared linear to surface distance look-up table for determining the surface distance of a linear value;

using the square look-up table to calculate the square of the linear distances; and using the squared linear to surface distance look-up table to convert the calculated square of the linear distances to surface distances.

11. A machine-readable medium comprising instructions, which when executed by a machine, cause the machine to perform a method to filter a search result set using distance criteria, the method comprising:

receiving a search request with search parameters, the search request including distance criteria;

retrieving a result set using the search parameters, the result set including a list of items and their geographical locations;

determining Normalized Cartesian co-ordinates for an origin location, the Normalized Cartesian co-ordinates obtained by adding to each of Cartesian co-ordinates X, Y, and Z a value of earth radius;

determining the Normalized Cartesian co-ordinates for the geographical location of each of the items;

using the Normalized Cartesian co-ordinates of the origin location and of the geographical location of each of the items to calculate a linear distance from the origin location to the geographical location of each of the items;

converting the calculated linear distances to surface distances from the origin location to the geographical location of each of the items;

determining whether the surface distance from the origin location to the geographical location of an item falls within the distance criteria;

for cases where it is determined the surface distance from the origin location to the geographical location of an item falls within the distance criteria then including the item in a result set; and outputting the result set.

12. A computerized system to filter a search result set using distance criteria, the system comprising:

a search engine for receiving a search request with search parameters, the search request including distance criteria, and retrieving a result set using the search parameters, the result set including a list of items and their geographical locations;

a processor to use Normalized Cartesian co-ordinates of an origin location and the geographic location of each item in the list of items to calculate a linear distance between the origin location and the geographical location of each of the items, and to convert the calculated linear distance to a surface distance between the origin location and the geographic location of each item, the Normalized Cartesian co-ordinates obtained by adding to each of Cartesian co-ordinates X, Y, and Z a value of earth radius;

a filter to filter out from the result set those items whose surface distances do not fall within the distance criteria; and

an output device to output the result set.