I was recently tasked with building an application that relied heavily on accurate time zone conversions. I, like many people I soon found out, thought there were just a handful of timezones and the usual select list would suffice. The deeper I looked into the problem, the deeper it got: the list above only shows a few time offsets from UTC, but it doesn't tell me, beyond a shadow of a doubt, exactly what time it is where the user is situated, nor can I rely on that time for calculations in the future. The fact is, here are a LOT of timezones in the world.

He came across the DateTimeZone class PHP has to offer and was happy to see it met his needs. Unfortunately, users weren't always sure what timezone they were in, so he came up with a system combining Google's Maps API and GeoNames.org. He includes the code for both the PHP and Javascript sides (the Javascript requires Mootools, but it could be easily adapted to any other Javascript libraries).

Basically, what I'm doing is plotting a radius around a point on a map, which is defined by the distance between two points on the map given their latitudes and longitudes. To achieve this I'm using the Haversine formula (spherical trigonometry). This equation is important in navigation, it gives great-circle distances between two points on a sphere from their longitudes and latitudes.

Included in the post is the code for three different implementations - PHP, Python and SQL, all using that same formula.

I reviewed the coordinates given by existing members and noticed a good number had visibly inverted latitude and longitude; so I inverted them again to place them where it appeared to make more sense (are there really PHP-GTK devs in the middle of the pacific, or near the South pole ?). So you may want to double-check your coordinates to make sure the values are correct, because it's likely I've not found every error.

He's also asking for the Brasil PHP-GTK community to include their information in the map as well as a request for anyone out there that might want to make a "prettier" icon for showing the developers on the map.

Oracle Spatial is a powerful library for adding location awareness to applications. This script uses the core subset of Spatial, called Oracle Locator, which is included in all Oracle Database editions.

His example connects to the database resource and makes a few example SQL queries: one that uses the sod_nn() function built in to the Spatial package to grab the store locations close to the customers, another that finds the latitude and longitude for a customer's information and a method for querying an object collection of locations in a given area.

The site offers "geo-nick", a simplistic API to obtain this [latitude and longitude] information coupled with the optional IRC nick field, to allow any developer to create mashups showing community PHP-GTK developers, as identified by nickname (no actual name information is made available through this API) on a map.

The post includes an example of how to use the API - what package to call and what the message should contain. The results are passed back in an array of nickname, lataitude, longitude.

Piggybacking on this new service, they also have a new tutorial showing how to access and use this service from a simple PHP-GTK2 application. It just grabs the results and dumps them into a simple text area in a window.