完成作业321

题目1.py

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+word = "Hello"
+print("1. 使用 ord() 函数：")
+for char in word:
+    ascii_val = ord(char)
+    print(f"   '{char}' -> {ascii_val}")
+
+print("\n2. 使用 chr() 函数验证：")
+
+ascii_value = 65
+char_from_ascii = chr(ascii_value)
+print(f"   ASCII码 {ascii_value} -> 字符 '{char_from_ascii}'")
+
+print("\n3. 完整转换验证：")
+print("   字符串 'Hello' 的ASCII码列表:")
+ascii_list = [ord(c) for c in word]
+print(f"   {ascii_list}")
+
+print("   从ASCII码列表恢复字符串:")
+recovered_word = ''.join(chr(code) for code in ascii_list)
+print(f"   {ascii_list} -> '{recovered_word}'")

题目3.py

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+import numpy as np
+
+A = np.array([3, 4])
+B = np.array([1, 2])
+
+A_plus_B = A + B
+print("1. A + B =", A_plus_B)
+
+two_A = 2 * A
+print("2. 2 * A =", two_A)
+
+norm_A = np.linalg.norm(A)
+print("3. 向量 A 的长度 =", norm_A)
+
+print("-" * 40)

题目4.py

@@ -0,0 +1,23 @@
+A1 = np.array([1, 2, 3])
+B1 = np.array([4, 5, 6])
+
+dot_product = np.dot(A1, B1)
+print("1. 点积 A*B =", dot_product)
+
+def cosine_similarity(v1, v2):
+    dot = np.dot(v1, v2)
+    norm_v1 = np.linalg.norm(v1)
+    norm_v2 = np.linalg.norm(v2)
+    return dot / (norm_v1 * norm_v2)
+
+cos_sim = cosine_similarity(A1, B1)
+print(f"2. 余弦相似度 = {cos_sim:.6f}")
+print(f"   精确分数形式: {dot_product}/({np.dot(A1, A1)}*{np.dot(B1, B1)}) = {dot_product}/{np.dot(A1, A1) * np.dot(B1, B1)}")
+
+A2 = np.array([1, 0])
+B2 = np.array([0, 1])
+cos_sim_special = cosine_similarity(A2, B2)
+print("3. 当 A = [1, 0], B = [0, 1] 时:")
+print("   - 点积 =", np.dot(A2, B2))
+print("   - 余弦相似度 =", cos_sim_special)
+