完成作业X

test3.py

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+import math
+A = [1, 2, 3]
+B = [4, 5, 6]
+def dot_product(v1, v2):
+    return sum(x * y for x, y in zip(v1, v2))
+A_dot_B = dot_product(A, B)
+print("1. A · B =", A_dot_B)
+def vector_norm(v):
+    return math.sqrt(sum(x ** 2 for x in v))
+def cosine_similarity(v1, v2):
+    dot = dot_product(v1, v2)
+    norm1 = vector_norm(v1)
+    norm2 = vector_norm(v2)
+    if norm1 == 0 or norm2 == 0:
+        return 0.0
+    return dot / (norm1 * norm2)
+cos_sim = cosine_similarity(A, B)
+print("2. 余弦相似度 =", round(cos_sim, 4))  
+A2 = [1, 0]
+B2 = [0, 1]
+cos_sim2 = cosine_similarity(A2, B2)
+print("3. A=[1,0], B=[0,1] 的余弦相似度 =", cos_sim2)
+print("   原因：点积为 0，说明两向量正交，夹角为 90°，所以余弦相似度为 0。")