修改龙格库塔bug

按方法整理/矩阵-SOR逐次超松弛迭代法.py

@@ -0,0 +1,62 @@
+import math
+
+#模 范数
+def Norm(x,v):
+    if len(x[0]) == 1:
+        if v == 1:
+            return sum([abs(i[0]) for i in x])
+        elif v == 2:
+            return (sum([i[0]**2 for i in x]))**0.5
+        elif v == float("inf"):
+            return max([abs(i[0]) for i in x])
+    else:
+        if v == 1:
+            return max([sum([abs(x[i][j]) for i in range(len(x))]) for j in range(len(x[0]))])
+        elif v == float("inf"):
+            return max([sum([abs(i) for i in x[j]]) for j in range(len(x))])
+    return None
+
+#SOR方法 逐次超松弛迭代
+def SOR(A,b,x,w,err,N):
+    count = 0
+    n = len(A)
+    while True:
+        count += 1
+        for i in range(n):
+            sum1 = sum(A[i][j] * x[j] for j in range(i))
+            sum2 = sum(A[i][j] * x[j] for j in range(i, n))
+            x[i] += w*(b[i] - sum1 - sum2) / A[i][i]
+        r = [[b[i] - sum(A[i][j] * x[j] for j in range(len(A[0])))] for i in range(n)]
+        err_now = Norm(r, float("inf"))
+        x_t = [round(i,5) for i in x]
+        print(f"第{count}次迭代, 误差 = {err_now:.5}, x = {x_t}")
+        if err_now < err:
+            return x, count, 1
+        
+        if count > N:
+            return None,count, 0
+        
+
+if __name__ == "__main__":
+    ##########################################################################
+    #把矩阵改成题干的矩阵，b改成题干结果，err精度要求修改##########################
+    A = [
+        [4,-1,0,-1,0,0],
+        [-1,4,-1,0,-1,0],
+        [0,-1,4,0,0,-1],
+        [-1,0,0,4,-1,0],
+        [0,-1,0,-1,4,-1],
+        [0,0,-1,0,-1,4]
+    ]
+    b = [2,3,2,2,1,2]
+
+    x = [0,0, 0, 0, 0, 0]   # 初始解
+    err = 1e-5              # 精度要求
+    w = 1                   # 松弛因子,题干要求    P201
+    x1,k,sta = SOR(A, b, x, w, err, 100)
+    print(f"w = {w}, 解为: {x1}, 迭代次数: {k}, 状态: {'收敛' if sta == 1 else '未收敛'}")
+
+    w = 1.1
+    x = [0, 0, 0, 0, 0, 0]
+    x2,k,sta = SOR(A, b, x, w, err, 100)
+    print(f"w = {w}, 解为: {x2}, 迭代次数: {k}, 状态: {'收敛' if sta == 1 else '未收敛'}")