rhumb
Computes the azimuth angle (clockwise from North) for the rhumb path (line of constant azimuth) between this location and a specified location. This angle can be used as the starting azimuth for a rhumb path beginning at this location, and passing through the specified location. This function uses a spherical model, not elliptical.
Return
the computed azimuth
Parameters
location
the rhumb path's ending location