def to_lat format = :dms, dp = 0
      return lat if !format
      GeoUnits::Converter.to_lat lat, format, dp
    end
def to_lat format = :dms, dp = 0
      return lat if !format
      GeoUnits::Converter.to_lat lat, format, dp
    end
Returns the latitude of this point; signed numeric degrees if no format, otherwise format & dp

 @param [String] format: Return value as 'd', 'dm', 'dms'
 @param [Numeric] dp: No of decimal places to display (0|2|4)

 @return   [Numeric|String]: Numeric degrees if no format specified, otherwise deg/min/sec