Convert UMC to Lat/Lon

[mossoi]

I've have the following formulae to convert latitude and longitude to UTM:

 

lon_utm = lon * 20037508.34 / 180

lat_utm = Math.log(Math.tan((90 + lat) * Math.PI / 360)) / (Math.PI / 180) * 20037508.34 / 180

 

I need the equivalent formulae to reverse this. Longitude I can do:

 

lon = lon_utm / 20037508.34 * 180

 

but I'm completely stuck on latitude (I'm a programmer not a mathematician!)

 

Can anybody give me some help or point me in the right direction please?

Edited July 28, 2009 by mossoi

[D H]

You are using some nonstandard terminology. As far as I can tell, UMC means United Methodist Church. Note: 20037508.34 is pi times the radius of the Earth.

[mossoi]

You're right, meant UTM rather than UMC, serves me right for not checking my acronyms!