/usr/share/doc/plotutils/ode/henon.ode is in plotutils 2.6-3.
This file is owned by root:root, with mode 0o644.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | # You may run this example by doing:
#
# ode < henon.ode | graph -T X -C
#
# or alternatively, to get a real-time plot,
#
# ode < henon.ode | graph -T X -C -x -0.6 0.6 -y -0.6 0.6
#
# This example shows a simple center with complicated orbits:
# the system investigated by Henon and Heiles.
# The Poincare plot is a graph of p1(t) vs. q1(t).
# Initial condations:
# stable: p1 = 1/3, q1 = 1/4, p2 = 0.1293144, q2 = 1/5
# unstable: p1 = 0.1, q1 = 0.1, p2 = 0.467618, q2 = 0.1
qone' = pone
qtwo' = ptwo
pone' = -qone - 2*qone*qtwo
ptwo' = -qtwo - qone*qone + qtwo*qtwo
pone = 1/3
qone = 1/4
ptwo = 0.1293144
qtwo = 1/5
print pone, qone
step 0,250
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