58 lines
1.6 KiB
Python
58 lines
1.6 KiB
Python
# /// script
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# requires-python = ">=3.11"
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# dependencies = ["numpy", "matplotlib"]
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# ///
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import numpy as np
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import matplotlib.pyplot as plt
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# 设置字体（优先使用中文字体，DejaVu Sans 作为 fallback）
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plt.rcParams['font.sans-serif'] = ['WenQuanYi Micro Hei', 'Noto Sans CJK SC', 'Microsoft YaHei', 'SimHei', 'SimSun', 'DejaVu Sans']
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plt.rcParams['axes.unicode_minus'] = False
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# 绑定图像尺寸和 DPI
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plt.figure(figsize=(8, 6), dpi=150)
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# 定义二次函数 y = -2x^2 + 8x - 3
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def quadratic_func(x):
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return -2*x**2 + 8*x - 3
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# 生成x值，覆盖关键区域
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x = np.linspace(-1, 5, 400)
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y = quadratic_func(x)
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# 绘制函数曲线
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plt.plot(x, y, label=r'$y = -2x^2 + 8x - 3$', color='blue', linewidth=2)
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# 标出顶点 (2, 5)
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vertex_x, vertex_y = 2, 5
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plt.plot(vertex_x, vertex_y, 'ro', markersize=8, label=f'顶点 ({vertex_x}, {vertex_y})')
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# 添加网格
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plt.grid(True, linestyle='--', alpha=0.6)
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# 设置坐标轴标签和标题
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plt.xlabel('x', fontsize=12)
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plt.ylabel('y', fontsize=12)
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plt.title('二次函数 $y = -2x^2 + 8x - 3$ 的图像', fontsize=14)
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# 设置坐标轴范围
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plt.xlim(-1, 5)
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plt.ylim(-5, 7)
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# 添加图例
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plt.legend()
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# 在顶点处添加注释
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plt.annotate(f'顶点\n({vertex_x}, {vertex_y})',
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xy=(vertex_x, vertex_y),
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xytext=(vertex_x + 1.2, vertex_y - 1),
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arrowprops=dict(arrowstyle='->', color='red', lw=1.5),
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fontsize=12,
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color='red',
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ha='center')
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# 保存图像
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plt.savefig('figure.png', bbox_inches='tight')
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plt.close()
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print("图像已保存: figure.png") |