matplotlib——sin，cos

import matplotlib.pyplot as pltimport numpy as npif __name__ == '__main__':    x = np.linspace(-np.pi, np.pi, 256, endpoint= True)    y = np.cos(x)    y1 = np.sin(x)    plt.plot(x,y)    plt.plot(x,y1)    plt.title("Functions $\sin$ and $\cos$")    plt.xlim(-3.0, 3.0)    plt.ylim(-1.0, 1.0)    plt.xticks([-np.pi, -np.pi/2, 0, np.pi/2, np.pi],           [r'$-\pi$', r'$-\pi/2$', r'$0$', r'$+\pi/2$', r'$+\pi$'])    plt.yticks([-1, 0, +1],               [r'$-1$', r'$0$', r'$+1$'])    plt.show()    plt.show()