Python代码为解决特征值问题，python特征值,''' lam,x =

Python代码为解决特征值问题，python特征值,''' lam,x =

''' lam,x = inversePower5(Bv,d,e,f,tol=1.0e-6).    Inverse power method for solving the eigenvalue problem    [A]{x} = lam[B]{x}, where [A] = [f\e\d\e\f] is    pentadiagonal and [B] is sparce. User must supply the    function Bv(v) that returns the vector [B]{v}.'''from numpy import zeros,dotfrom LUdecomp5 import *from math import sqrtfrom random import randomdef inversePower5(Bv,d,e,f,tol=1.0e-6):      n = len(d)    d,e,f = LUdecomp5(d,e,f)    x = zeros(n)    for i in range(n):          # Seed {v} with random numbers        x[i] = random()    xMag = sqrt(dot(x,x))       # Normalize {v}    x = x/xMag    for i in range(30):         # Begin iterations             xOld = x.copy()         # Save current {v}        x = Bv(xOld)            # Compute [B]{v}        x = LUsolve5(d,e,f,x)   # Solve [A]{z} = [B]{v}        xMag = sqrt(dot(x,x))   # Normalize {z}        x = x/xMag        if dot(xOld,x) < 0.0:   # Detect change in sign of {x}            sign = -1.0            x = -x        else: sign = 1.0        if sqrt(dot(xOld - x,xOld - x)) < tol:            return sign/xMag,x    print 'Inverse power method did not converge'