plotutils-graph-patches-lloda/ode-examples/bead.ode

# This example simulates a bead sliding on a smooth circular wire.  The
# output displays the height of the bead as a function of time.
#
# You may run this example by doing:
#
#    ode < bead.ode | graph -T X -C
# 
# or alternatively, to get a real-time plot,
#
#    ode < bead.ode | graph -T X -C -x 0 5 -y 0 2.5
#

a = 1  # radius of circular wire
g = 10 # acceleration due to gravity
w = 10 # angular velocity of circular wire

the' = vthe
vthe' = (w^2)*sin(the)*cos(the) - (g/a)*sin(the)
the = 0.1
vthe = 0

print t, the
step 0,5