/usr/share/doc/plotutils/ode/soliton.ode is in plotutils 2.6-3ubuntu1.
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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 | # You may run this example by doing:
#
# ode < soliton.ode | graph -T X -C
#
# or alternatively, to create a real-time plot,
#
# ode < soliton.ode | graph -T X -C -x 5 15 5 -y -3 3
# This example numerically solves an initial value problem arising in
# John Selker's soliton thesis:
#
# x'' = (2 / t) * x' + B * x
# B = -1
# x(5) = 0
# x'(5) = 1
x' = vx
vx' = 2 / t * vx + B * x
B = -1
x = 0
vx = 1
print t, x
step 5, 15
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