static double simpleAngle(Geo p1,Geo p2){
  return Math.acos(p1.dot(p2) / (p1.length() * p2.length()));
}

static double simpleAngle ( Geo p1 , Geo p2 ) { return Math . acos ( p1 . dot ( p2 ) / ( p1 . length ( ) * p2 . length ( ) ) ) ; }
simple vector angle ( not geocentric ! )
