# a rope slides frictionlessly down the edge of a table
# x'' = g/l * x

coefficient(1): 1 -> x0'   # initial speed
coefficient(2): -1 -> -x0  # initial length of rope already over the edge of the table
coefficient(3): g/l        # gravity constant (g) devided by the length of the rope (l)

iintegrate (x'') -> -x':
   IC: x0'
iintegrate (-x') -> x:
   IC: -x0
x * g/l -> g/l*x = x''

# note: positive x-axis in the direction of the falling rope (so down)
#       for visualization, -x is displayed
invert (x) -> -x # goes to output x