/usr/share/doc/plotutils/ode/dynamo.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 30 31 32 33 34 35 36 37 38 39 40 | # This is a disk dynamo simulation of the earth's magnetic field.
# It attempts to simulate the dramatic switch in the polarity
# of the field that takes place every eon or so.
#
# Source: Michael Steele, B.A. thesis, Reed College, 1981 (Physics)
# You may run this example by doing:
#
# ode < dynamo.ode | graph -T X -C
#
# or alternatively, to get a real-time plot,
#
# ode < dynamo.ode | graph -T X -C -x 0 10 -y -10 10
#
# The equations are:
#
# w' = Q -zy - Vw
# y' = S( Az - y)
# z' = wy - z
# S = 5
# V = 1
# Q = 14.625
# A = 1
A = 1
V = 1
Q = 14.625
S = 5
w' = Q - z * y - V * w
y' = S * ( A * z - y)
z' = w * y - z
w = 1
y = 1
z = 1
print t, z
step 0, 10, .01
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