Navigation Predicates

• lat-long is a list (latitude longitude) where the values are in floating degrees; negative longitude denotes west longitude.

• UTM or Universal Transverse Mercator is a way of representing positions on Earth that locally maps locations to a flat, Cartesian x-y grid. UTM is a list (easting northing) where the values are in meters. northing is meters north of the equator and easting is meters east of center on a six-degree strip of longitude, plus 500000.

  
  ((cartesian p (ll2utm q))   (lat-long p q))
  

  ``The cartesian form of p is (ll2utm q ) if the lat-long form of p is q.''

• city is a symbol, such as austin. An alist maps a city to its lat-long.

• (movefrom a b c ) specifies that c is the result of moving from a by an amount b.