NB. Iterative solution of Kepler's Equation:
NB. Solves  "E - e sin E = M"   for E.
NB. (tacit expression due to Dan Bron)
NB. Usage: e KE M --> E

KE=: ,~ (p. sin)^:_ ]

NB. This is a simple iteration, but seems
NB. to converge quite fast as long as the
NB. eccentricity e is not closer to one 
NB. than ~0.995. For multiple values of M
NB. write, e.g., 
NB. E=. 0.8 KE"0 M=. 2p1*int01 1000.
NB. load'plot'
NB. 'pensize 3' plot M;(E-M)