多项式求根方法

 

import numpy as np

# y=3x^3+2x^2+9x+10

def root_of(a):

    mat = np.zeros((a.shape[0]-1, a.shape[0]-1), dtype=np.double)

    a=a/a[0]

    for i in range (a.shape[0]-1):

        mat[0][i] = a[i+1]

    for i in range(a.shape[0]-2):

        mat[i+1][i] = -1.0

    w,v = np.linalg.eig(mat)

    return -w

a=np.array([3,2,9,10])

print("root:", root_of(a))