It's just a copy-paste of the equation from the Wikipedia article on the geoid: http://en.wikipedia.org/wiki/Geoid#Spherical_harmonics_representation http://en.

It's just a copy-paste of the equation from the Wikipedia article on the geoid: http://en.wikipedia.org/wiki/Geoid#Spherical_harmonics_representation http://en.wikipedia.org/wiki/Geoid#Spherical_harmonics_repre...