Near Latitide&Longitide; for given postcode

[eluser]veledrom[/eluser]
Hi,

Apologised if not relevant to CI.

I am using http://codeigniter.com/wiki/Google_Maps_API_V3_Library for my purposes.

Let me explain what I need with an example.

I have a postcode NW1 5LR and its LATITUDE:51.546069024064 LONGITUDE:-0.235949008191785 coming from user entry. I also have many other postcodes and their Latitide&Longitide; values in database.

What formula should I use to get only those postcodes which are in 1 mil away maximum?

Thanks