Seite - 169 - in Programming for Computations – Python - A Gentle Introduction to Numerical Simulations with Python

5.1 FiniteDifferenceMethods 169 def dsdt(t): return 0 def g(x, t): return 0 Parameterscanbeset as L = 0.5 beta = 8.2E-5 N = 40 x = linspace(0, L, N+1) dx = x[1] - x[0] u = zeros(N+1) U_0 = zeros(N+1) U_0[0] = s(0) U_0[1:] = 283 Letususe t D0:00034375.Wecannowcallode_FEandthenmakeananimation on the screen toseehowu.x;t/develops in time: t0 = time.clock() from ode_system_FE import ode_FE u, t = ode_FE(rhs, U_0, dt, T=1*60*60) t1 = time.clock() print ’CPU time: %.1fs’ % (t1 - t0) # Make movie import os os.system(’rm tmp_*.png’) import matplotlib.pyplot as plt plt.ion() y = u[0,:] lines = plt.plot(x, y) plt.axis([x[0], x[-1], 273, s(0)+10]) plt.xlabel(’x’) plt.ylabel(’u(x,t)’) counter = 0 # Plot each of the first 100 frames, then increase speed by 10x change_speed = 100 for i in range(0, u.shape[0]): print t[i] plot = True if i <= change_speed else i % 10 == 0 lines[0].set_ydata(u[i,:]) if i > change_speed: plt.legend([’t=%.0f 10x’ % t[i]]) else: plt.legend([’t=%.0f’ % t[i]]) plt.draw() if plot: plt.savefig(’tmp_%04d.png’ % counter) counter += 1 #time.sleep(0.2)