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from scitools.std import *
from time import sleep
x = seq(0, 15, 0.1)
def f(x, t):
return exp(-0.1*t)*exp(-(x-t)**2)
dt = 0.1 # time step
tstop = 15 # end time
# animation requires axis keyword in plot command, not separate axis
# function call
t = 0
while t <= tstop:
y = f(x, t)
plot(x, y, axis=[0, 15, -0.1, 1.1])
t += dt
sleep(0.2) # control speed
# animate two curves
def f2(x, t):
return exp(-(x-t)**2)
t = 0
while t <= tstop:
y = f(x, t)
y2 = f2(x, t)
plot(x, y, 'r-', x, y2, 'b-', axis=[0, 15, -0.1, 1.1])
t += dt
# draw a line for the top of the f curve:
t = 0
xtop = []; ytop = []
while t <= tstop:
y = f(x, t)
y2 = f2(x, t)
xtop.append(t) # top point corresponds to x=t
ytop.append(f(t,t))
plot(x, y, 'r-', x, y2, 'b-', xtop, ytop, 'y--', axis=[0, 15, -0.1, 1.1])
t += dt
# make hardcopy of the animation:
# (first clean up old tmp_*.ps files)
import os, glob
for file in glob.glob('tmp_*.ps'): os.remove(file)
t = 0
dt = 0.25
frame_counter = 0
while t <= tstop:
y = f(x, t)
y2 = f2(x, t)
filename = 'tmp_%04d.ps' % frame_counter
frame_counter += 1
plot(x, y, 'r-', x, y2, 'b-', hardcopy=filename, axis=[0, 15, -0.1, 1.1])
t += dt
cmd1 = 'ps2mpeg.py tmp_*.ps tmp.mpeg'
print 'make MPEG move:\n', cmd1
cmd2 = 'convert -delay 20 tmp_0*.ps tmp.gif'
print 'make animated GIF file:\n', cmd2
#os.system(cmd1)
#os.system(cmd2)
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