计算方法 | 实用的乘幂法求主特征值

这个不是很难，看看就好。

丢代码：

# 矩阵乘法函数
def matrix(a1, a2):
    h1 = len(a1)
    w1 = len(a1[0])
    h2 = len(a2)
    w2 = len(a2[0])
    # 定矩阵大小
    h3 = h1
    w3 = w2
    a3 = [[0 for j in range(w3)] for i in range(h3)]
    # print((h3,w3))
    # print(a3)
    for i in range(h3):
        for j in range(w3):
            sum = 0
            for k in range(h3):
                sum += a1[i][k] * a2[k][j]
                # print(a1[i][k],a2[k][j])
                # print("sum += a1[{}][{}] * a2[{}][{}] -> {}".format(i,k,k,j,a1[i][k] * a2[k][j])) 
            a3[i][j] = sum
            # print("a3[{}][{}] = {}".format(i,j,sum))
    # print(a3)
    return a3
    
    
# mat = eval(input("请输入矩阵："))
# 测试数据
mat = [[3,-4,3],[-4,6,3],[3,3,1]]
mat = [[2,3,2],[10,3,4],[3,6,1]]

v = u = [[0],[0],[1]]
round = 10
for i in range(round):
    u = matrix(mat, v)
    print(u, end=" --- ")
    # 求max(u)
    _max = 0
    for i in u:
        for j in i:
            if abs(j) > _max:
                _max = j
    # 除_max
    for i in range(len(u)):
        for j in range(len(u[0])):
            v[i][j] = u[i][j] / _max
    print(v, end=" --- ")
    print(_max)