How large a database is required for the NAC mail sorting computer?
The database for the international postal zones will save all the information of the border of these zones. People can estimate how long all the border add together. There are less than 200 countries in the world. The biggest one is Russia which has border less than 40,000 km. The most conservative estimate is to assume each country is as large as Russia and the length of the border of all the international postal zones equals to 200×40,000=8,000,000 km. Now we need the information only for the purpose of the determination of the international zone of a mail destination, so we can ignore all the landscape of the area along the border and simply consider the information of the border. Assume that the border changes smoothly in the scale of 1 km in average, so we can use some interpolation scheme to epresent each 1 km border, i.e., we only need to save the coordinates of one point for each km. So all together, the database will contain 16,000,000 double precision data, which will be 8×16
