matplotlib plots plots with formulas in legend labels

a code

1. import numpy as np
2. import matplotlib.pyplot as plt
3. x = np.linspace(0,2*np.pi,500)
4. y = np.sin(x)
5. z = np.cos(x*x)
6. plt.figure(figsize=(8,4))
7. #标签前后加$将使用内嵌的LaTex引擎将其显示为公式
8. plt.plot(x,y,label='$sin(x)$',color='red',linewidth=2)#红色，2个像素宽
9. plt.plot(x,z,'b--',label='$cos(x^2)$')#蓝色，虚线
10. plt.xlabel('Time(s)')
11. plt.ylabel('Volt')
12. plt.title('Sin and Cos figure using pyplot')
13. plt.ylim(-1.2,1.2)
14. plt.legend()#显示图示
15. plt.show()

Second run results