#! /usr/bin/dc

10k

0 0 :X
0 0 :Y
0.5 1 :X
0.87 1 :Y
1 2 :X
0 2 :Y

0 0 sx sy

0.77777 sr

# Repeat
[ 1 -
r d x r
d 0 !=R] sR

[#PLOT 2]p
[o]p
[e]p

# Generate pseudo random number
[1 lr - lr * 4 * sr 
lr 100000 * 0k 1 / 3 %
10k si

# Choose coordinate with the randomly generated index i
# and calculate the new position based on the current position and
# the chosen destination
li ;X lx - 2 / lx + sx
li ;Y ly - 2 / ly + sy

# Plot
[p ]P lx n [ ]P ly p sz
] 

# Repeat 10000 times
10000 lR x

[x]p