# Gravity – 1-dimensional.LACE
# The small mass m moves along the direct connection line towards mass M.  
# r'' = -gamma*M / r^2

coefficient(1): +1 -> r0' # -1 to move initially towards M, +1 to  move away from it
coefficient(2): -1 -> -r0 # initial distance of m to M
coefficient(3): +1 -> gamma*M # will be inverted in division

iintegrate r'' -> -r'
  IC: r0'
iintegrate -r' -> r
  IC: -r0
multiply r, r -> r^2
idivide gamma*M, r^2 -> -gamma*M/r^2
assign -gamma*M/r^2 -> r''

output(x): r      # distance
invert -r' -> r'
output(y): r'     # speed and direction
output(z): r''    # acceleration (always towards M)