単に陰解法にしたバージョン。
#!/opt/local/bin/python2 # -*- coding: utf-8 -*- # heat1d-i-v3.py import sys import numpy as np import matplotlib.pyplot as plot import matplotlib.animation as animation import trid def f(x): return min(x,1-x) N=50 x=np.linspace(0.0, 1.0, N+1) u=np.vectorize(f)(x) h=1.0/N lam=0.5 tau=lam*h*h theta=0.5 dt=0.001 skip=int(dt/tau) Tmax=1 nmax=int(Tmax/tau) n=0 ad = (1+2*theta*lam)*np.ones(N-1) al = -theta*lam*np.ones(N-1) au = -theta*lam*np.ones(N-1) trid.trilu(N-1,al,ad,au) fig=plot.figure() window=fig.add_subplot(111) line,=window.plot(x,u) def update(i): global n if n<nmax: for j in xrange(skip): u[1:N]=(1-2*(1-theta)*lam)*u[1:N]+(1-theta)*lam*(u[0:N-1]+u[2:N+1]) trid.trisol(N-1,al,ad,au,u[1:N]) n=n+skip line.set_ydata(u) else: sys.exit(0) return line, ani=animation.FuncAnimation(fig, update, interval=100) plot.show()
桂田 祐史