求单位向量（向量归一化）

def solve():
    import matplotlib.pyplot as plt
    import numpy as np
    from math import sqrt
    
    v = (-1, -1, 2)
    length_v = sqrt(v[0]**2 + v[1]**2 + v[2]**2)
    unit_v = (v[0]/length_v, v[1]/length_v, v[2]/length_v)
    
    fig, ax = plt.subplots(figsize=(8, 6))
    
    vectors = [f"原向量 v = {v}", f"单位向量 = ({unit_v[0]:.4f}, {unit_v[1]:.4f}, {unit_v[2]:.4f})"]
    lengths = [length_v, 1]
    colors = ['blue', 'red']
    
    ax.barh(vectors, lengths, color=colors, alpha=0.7)
    ax.set_xlabel('长度')
    ax.set_title(f'向量归一化: 长度 {length_v:.4f} → 1')
    ax.grid(axis='x', alpha=0.3)
    
    plt.tight_layout()
    plt.show()
    
    print(f"单位向量 = ({unit_v[0]:.4f}, {unit_v[1]:.4f}, {unit_v[2]:.4f})")