I am doing some work with the Military Grid Reference System (MGRS), which is based on Universal Transverse Mercator (UTM).
I find that I need to convert from UTM northing and longitude (actually, delta angle between desired longitude and appropriate UTM central meridian) to latitude. I've searched for days and cannot find this conversion.
I need an algorithm. Can anyone point me to a reference to such an algorithm, or to open source software that does this conversion?