import numpy as np
def Jacobi(A, b, iter_n, initial_guess=0):
n = len(A)
D = np.diag(A)
R = A - np.diag(D)
x_i = initial_guess * np.ones(n)
for i in range(iter_n):
print('x_',i,'=',x_i)
x_i = (b - R.dot(x_i)) / D
return x_i
def A_ij(n):
A = np.empty((n, n))
for i in range(n):
A[i, i] = 2
for i in range(n-1):
A[i,i+1]=A[i+1,i]=1
return A
def b_i(n):
b=np.empty(n)
b[0]=1
b[n-1]=-1
return b
def x0(n):
return np.zeros(n)
print(Jacobi(A,b,100,x0))
# -*- coding: utf-8 -*-
#Jacobi迭代法 输入系数矩阵mx、值矩阵mr、迭代次数n、误差c(以list模拟矩阵 行优先)
def Jacobi(mx,mr,n=100,c=0.0001):
if len(mx) == len(mr): #若mx和mr长度相等则开始迭代 否则方程无解
x = [] #迭代初值 初始化为单行全0矩阵
for i in range(len(mr)):
x.append([0])
count = 0 #迭代次数计数
while count < n:
nx = [] #保存单次迭代后的值的集合
for i in range(len(x)):
nxi = mr[i][0]
for j in range(len(mx[i])):
if j!=i:
nxi = nxi+(-mx[i][j])*x[j][0]
nxi = nxi/mx[i][i]
nx.append([nxi]) #迭代计算得到的下一个xi值
lc = [] #存储两次迭代结果之间的误差的集合
for i in range(len(x)):
lc.append(abs(x[i][0]-nx[i][0]))
if max(lc) < c:
return nx #当误差满足要求时 返回计算结果
x = nx
count = count + 1
return False #若达到设定的迭代结果仍不满足精度要求 则方程无解
else:
return False
#调用 Jacobi(mx,mr,n=100,c=0.001) 示例
mx = [[8,-3,2],[4,11,-1],[6,3,12]]
mr = [[20],[33],[36]]
print(Jacobi(mx,mr,100,0.00001))