I've already written about conversion of postal addresses to latitude and longitude using Google's interface - but what is I want to convert the Ordinance Survey's grid references into latitude and longitude? Google's interface doesn't support the OS units - and in any case it's "just" a a calculation. I have put quotes around the word "just" because it's actually a complex calculation that I had no desire to re-code from learned papers.

Of course ... it's been done already. Perl's Geography::NationalGrid module which you can download from the CPAN. Now I wanted to use that in a PHP page to demonstrate to you, so I've written a quick Perl command line program that my PHP calls up when it needs to and .... bob's your uncle.

Try it out here (examples ST906637 is in Melksham ... SJ347904 is in Liverpool) :

Enter a grid reference:

The source code is also available for you:
The Perl command line program
The PHP which calls up that Perl

External links -
Descritpion of coordinate system and conversion algorithms (.pdf)
Perl Cpan module
(written 2007-10-14 07:39:28)

 H999 - Additional PHP Material
H309 - PHP - Maps, Graphics and Geographics
P219 - Perl - Libraries and Resources
H115 - Designing PHP-Based Solutions: Best Practice

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Dont just convert to Perl - re-engineer!
Business to Business Networking - North and West Wilts / Melksham
First Alternative / what has happened there?
Autumnal lighting on a London trip
Ordnance Survey Grid Reference to Latitude / Longitude
Converting from postal address to latitude / longitude
Controlling and labelling Google maps via PHP
Well House Manor - a year on
Error logging to file not browser in PHP
New software product for warmblooded programmers
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